Before I discuss the diet plan for weight loss, the subject matter of this post, it would be worthwhile to discuss certain salient aspects of obesity. Obesity is a multifactorial disease and is the result of a complex interplay of genetic, environmental, metabolic, physiologic, behavioural and social factors; the underlying mechanism is a sustained positive energy imbalance (i.e. the energy intake is more than the expenditure). Therefore, irrespective of the cause(s) of obesity in an individual, the basic concept of weight loss for the management of obesity revolves around energy balance between the number of calories you consume and the number of calories your body uses. To lose weight, it is necessary to create a sustained negative energy imbalance, i.e. reduce energy intake below the energy expenditure and sustain it in the long-term. Though there are many strategies available, however in the present post, my focus will be primarily on formulating a diet plan for weight loss.
Obesity and its impact
The world is in the grip of an obesity epidemic. In my post, Is obesity a disease or risk factor for other conditions? I had discussed the magnitude of obesity and had also highlighted that today most of the major international and national health organisations, including the World Health Organization (WHO), World Obesity Federation, and American Medical Association recognise obesity as a disease. In my post Childhood obesity: a serious public health challenge and Complications of Obesity: the mother of all diseases, I had discussed the health implications of obesity. In brief, as is evident from the above posts, obesity is a ‘gateway’ for many other diseases, such as dyslipidemia (abnormally elevated cholesterol or fats [lipids] in the blood), hypertension, diabetes and cardiovascular diseases. Furthermore, in my post Weight Bias: pervasive yet hidden harm of obesity, I had discussed the various psycho-social complications of obesity.
Obesity can be said to be a “canary in a coal mine” signalling problems in the broader environment. Obesity should, therefore, be seen as one of the main targets for current efforts to combat the increasing lifestyle disease epidemic.
Treatment options for obesity
Broadly speaking, the following options are available for the treatment of obesity.
- Lifestyle interventions
- Dietary interventions
- Physical activity and exercise interventions
- Behavioural therapy
- Medications for weight loss (pharmacotherapy)
- Bariatric surgery
Lifestyle interventions are the bedrock of management of obesity and remain an integral part of the management even when patients undergo bariatric surgery; similarly, pharmacotherapy at best can be labelled as an adjunct therapy to lifestyle interventions.The goal of lifestyle interventions, including a diet plan for weight loss, is to create a sustained negative energy imbalance by reducing caloric intake through dietary interventions and increasing expenditure through physical activity and exercise interventions (a combination of both these strategies gives the best results). As behaviour patterns play an important role in the causation of obesity, therefore behaviour therapy is often a key part of the management of obesity. In short, the foundation of effective obesity treatment centres on assisting the patient to make healthier dietary and physical activity choices that will lead to weight loss and reversal of comorbidities.
These lifestyle interventions resonate with the principles of healthy living advocated centuries ago by the Greek philosopher and physician Hippocrates (c. 460 – 370 BC). The Corpus Hippocraticum, a collection of around 60 early Ancient Greek medical works strongly associated with Hippocrates and his teachings, recommends the observation of nature and the study of evidence in the search for causes of disease. There were two main areas to study: alimentation (the nourishment of life) and the environment we inhabit. Hippocrates understood that the underlying principles of health were food and exercise, or work and that a high food intake meant that a lot of hard work was needed for it to be properly assimilated. A failure to balance an excess of either would upset the body’s metabolism and disease would surely follow. ‘Men’ he wrote, cannot live healthily on food without a certain amount of exercise.
Setting weight loss targets
Over recent years, goal setting for ‘successful’ obesity treatment has changed markedly. In the past, “goal bodyweight” of a successful weight loss program meant attainment of an ‘ideal’ body weight, which takes into consideration the body composition, and not merely the total body weight. An ideal body weight not only takes into account the desirable body fat, but also the desired lean body mass or fat-free mass. In the treatment of obesity, even though attainment of ideal body weight may be desirable, but more often than not it is not realistic. However, the good news is that various studies have convincingly proven that modest but sustained weight loss is of considerable benefit to obese patients. Expert panels and governmental guidelines now recommend that obese persons must aim to achieve modest (i.e. reasonable) reductions in body weight rather than striving for ideal weight.
Currently, World Health Organisation, the Institute of Medicine of the National Academy of Sciences, USA, and the National Heart Lung and Blood Institute of USA recommend that an overweight/obese person should initially set a target of losing 5 to 15% of the current body weight, depending on the degree of obesity. Fresh targets can be set for additional weight loss once this target is successfully achieved and maintained. Setting the initial weight loss target beyond the above recommendation often gives the patient an unrealistic and potentially unattainable target in the light of current treatment methods available.
Unfortunately, in reality, these figures recommended by experts are not what the obese patients hope for and expect from their treatment – often there is a dramatic disparity between patient expectations and professional recommendations. This is amply illustrated in a study done in the US, titled ‘What is reasonable weight loss? Patients’ expectations and evaluations of obesity treatment outcomes’, published in the Journal of Consulting and Clinical Psychology in 1997. This study assessed the patient’s goals, expectations, and evaluations of various outcomes before, during, and after 48 weeks of treatment. In the study, sixty obese women with a mean age of 40 years and a mean weight of 99.1 kg, and a mean BMI of 36 kg/m2 were studied. Before the study, each patient was required to define her ‘goal weight’, ‘dream weight’, ‘happy weight’, ‘acceptable weight’, and disappointed weight. The goal weight was 66 kg, dream weight 61 kg, happy weight 68 kg, acceptable weight 74 kg, and disappointed weight 82 kg. For the average patient, a 17 kg weight loss (approx. 17% of the baseline weight) was considered disappointing and not successful despite it exceeding the professional recommendation and producing significant health benefits. After 48 weeks of therapy, 9% of the women were happy, 24% had acceptable weight loss, 20% were disappointed, and 47% were worse than disappointed (i.e. lost less than 18% of their initial weight). Overall about two-thirds of the women were dissatisfied with their weight loss. These data illustrate the dramatic disparity between the patient’s expectations and professional recommendations. This disappointment was mainly due to the weight loss not meeting their cosmetic expectations, despite the potential medical benefits.
Unrealistic patient weight loss expectations in the treatment of obesity may lead to frustration and drop-out because of perceived treatment failure. More importantly, it hampers the modest success which can be achieved, producing significant health benefits in the patient. This underscores the need for educating the patient about the realistic weight loss outcome at the beginning of the treatment itself. Health care professionals need to ensure that the patients understand that “small weight losses lead to big health gains.” They also need to understand that they must set realistic goals rather than optimistic goals. Thereafter, these goals need to be monitored and reviewed regularly. Perception of ‘weight normalisation’ as something going back to the weight that somebody was when they were 18 or 21 years old is mostly unsustainable.
In the context of the management of obesity, the term diet is defined as a regimen of eating and drinking sparingly to reduce one’s weight.
History of dieting for weight loss
The media’s relentless obsession with size may be perceived as the twenty-first-century phenomenon, however, body shape, fashion and dieting have always been close bedfellows. The current obesity epidemic may have escalated in the last 3-4 decades but body-shaping, dieting and fear of fat all have a long and wretched history. The ideal body has always been revered in the arts, medicine, politics and philosophy and that ideal has changed over time; preferred body shape alters as societies change.
The term ‘diet’ originates from the Greek word diaita which means a “way of living” as advised by a physician. To the Greek doctors the way of life comprised of three components: drink, food and exercise. In the treatise Airs, Waters, Place, which is part of the Corpus Hippocraticum, the Hippocratic author defines the regimen of inhabitants, which the itinerant doctor should observe when he arrives in a city that is unknown to him and where he is going to practice his art:
He should consider the regimen of the inhabitants, what their preferences are, whether they enjoy drinking, taking lunch at midday and are inactive, or whether they enjoy exercise and exertion, eat a lot and drink little.
In her book ‘Calories and Corsets: A History of Dieting over 200 Years’, award-winning historian Louise Foxcroft writes – we have been struggling with what to eat, when and how much, ever since the Greeks and the Romans first pinched an inch. Foxcroft reveals the extreme and often absurd lengths people will go in order to achieve the perfect body, from eating carbolic soap to chewing every morsel hundreds of times to a tasteless pulp. ‘Calories and Corsets’ is packed with jaw-dropping anecdotes about the pursuit of the ideal body through dieting. Shockingly, she exposes the tyranny that dieting imposes on women in particular. Corsets are just one example. In early-modern Britain, women might bind them so tightly that they gashed their sides. When 16th Century French surgeon Ambroise Pare performed autopsies on “pretty women with slender waists”, he was able to lift the skin, revealing “their ribs which overlapped each other”.
Though historically, diet craze has been driven primarily by appearance, however, as highlighted in my post What is obesity – is it merely about BMI? obesity is NOT just a cosmetic consideration; rather, it is a chronic, relapsing, progressive disease process. And as highlighted above, obesity is a gateway for many other diseases. In 2000, the WHO labelled obesity as the most blatantly visible, but most neglected public-health problem. Weight loss in people with obesity has proven medical benefits and hence needs to be a top priority for all concerned.
Weight loss and regain
Though, lifestyle interventions encompassing diet plan for weight loss, physical activity and behavioural modifications often lead to weight loss, however, over the long term, a vast majority of individuals regain the weight they have lost. The available data indicate that ranging from 30% to 50% of the lost weight is regained by the end of the first-year follow-up, with nearly all remaining lost weight regained thereafter in the vast majority of individuals. According to the National Health and Nutrition Examination Survey (NHANES), conducted by the National Center for Health Statistics, in the United States, a mere one in six overweight and obese adults reported maintaining a weight loss of at least 10% for one year, at any point in their lives. According to the data published in the International Journal of Obesity, based on the definition of successful maintenance of weight loss (the most commonly followed definition of successful maintenance of weight loss was proposed by Wing and Hill; they define successful maintenance of weight loss as “intentionally losing at least 10 per cent of the initial body weight and keeping it off for at least one year.”), approximately a quarter of overweight individuals report successfully maintaining weight loss. Thus, long-term weight loss maintenance remains the main challenge of obesity treatment. Various studies have shown that this relapse has a physiological basis and is not simply the result of the voluntary resumption of old habits. Given the physiological tendency to regain weight, the key to achieving and maintaining a healthy weight in the long-term isn’t about short-term dietary changes. Instead what is needed is life-long changes in the lifestyle that includes healthy eating, regular physical activity, and balancing the number of calories you consume with the number of calories your body uses.
With the rapid rise in the obesity epidemic, as millions of people struggle with their weight and seek answers about what they can do to slim down, the associated myths and anxieties are driving today’s multi-billion-dollar dieting industry, valued at $60 billion in the US alone. According to Nielson BookScan (a data provider for the book publishing industry), about 5 million diet books, which is just one segment of the dieting industry, are sold in the US alone every year – around half of the entire total health and fitness category in 2015. People profiting off our weight woes, failure to successfully lose and maintain weight, is nothing new. According to Foxcroft, dieting had become a commercial enterprise as early as the 18th century.
As per a review article titled Adult Weight Loss Diets: Metabolic Effects and Outcomes Published in the journal Nutrition in Clinical Practice in Dec 2014, an estimated 1000 weight-loss diets have been developed with more appearing in the lay literature and the media regularly. The principal factor fuelling this drive for newer diets is that the commercialization potential of breakthrough diets is substantial. The fact that there are so many diet plans for weight loss available suggests that, to date, no one diet plan has been universally successful at inducing and maintaining weight loss. If someone had found the fix for this immensely vexing and complex problem, we wouldn’t be facing an obesity crisis.
While discussing the specifics of a diet plan for weight loss, it would be prudent to mention that the use of the term ‘diet’ for the long-term management of obesity may not be very appropriate. Normally due to problems encountered in adherence to a particular ‘diet’ in the long-term, in practice, you can follow a ‘diet’ only for a short period. However, in individuals with weight problems, they need to ‘eat’ healthy for the rest of their lives. So, managing weight problems means talking about ‘eating’ healthy in the long term –NOT ‘going on a diet’...in other words, it’s going to be a journey. In this context, the type of dietary approach the patient might adhere to and the patient’s readiness to change are major factors which will determine the outcome of a diet plan for weight loss.
Determinants of outcome of a diet plan for weight loss
The core principle of any obesity treatment is that it must shift the balance between energy intake and energy expenditure. As highlighted above, treating obesity requires creating a state of negative energy balance, therefore a reduction in energy intake is the primary factor that needs to be addressed in a dietary intervention designed to promote weight loss. Several dietary approaches can reduce energy intake, with some approaches more greatly reducing energy intake than others. Another important factor which predicts the success of a diet plan for weight loss is ‘adherence’ to the diet plan. Various studies have revealed that the success of a diet is most predicted by adherence, with little effect of the brand or type of diet. Various research studies have convincingly demonstrated that the macronutrient composition (proportion of the three macronutrients in the diet viz. carbohydrate, fat & protein) of a diet does not impact the weight outcome; any reduced-calorie diet will result in clinically meaningful weight loss, regardless of which macronutrient they emphasise. After all, a calorie reflects food energy, regardless of the food source. In other words, a calorie is a calorie, irrespective of its source. From an energy standpoint, 100 calories from mayonnaise equal 100 calories from carrots. However, one important difference between these two sources is that carrots being a low-energy-dense food have a much greater satiating effect. On the other hand, mayonnaise is a high-energy-dense food and is less satiating; this can lead to overconsumption. Ultimately, the best diet plan for weight loss is the one the patient will follow and incorporate into his or her daily life for lifelong maintenance of healthy body weight. Furthermore, various studies have revealed that those individuals who did a better job of adhering to a low-calorie diet, regained less weight at the end of 1st and 2nd year following the weight loss; high adherers regained only 50% of the weight that was lost, compared with 99% regain for low adherers. This finding indicates that prior adherence to a low-calorie diet intervention may be a useful tool for identifying individuals who are at particular risk for subsequent weight regain for at least 2 years.
Strategies to improve adherence
Many factors influence adherence to a diet plan for weight loss including food preferences, cultural or regional traditions, food availability, food intolerances, and motivation. Furthermore, diet cannot be addressed only as a biochemical process, since it is strongly influenced by human behaviour and environmental factors. There are four key strategies to improve adherence to dietary weight-loss interventions. These include:
- designing diets to help reduce the weight loss-induced drive to eat.
- tailoring the diet to match dietary preferences (while meeting nutritional requirements).
- make changes gradually
- promoting self-monitoring of food intake.
1. Diets to help reduce the weight loss-induced drive to eat – In response to energy restriction and weight loss, a range of compensatory responses, including increased drive to eat, are triggered in the body that collectively oppose ongoing weight loss and promote weight regain. The compensatory increase in the drive to eat during weight loss is induced by multiple pathways, including neural alterations of the regulation of energy balance in the brain as well as alterations in the secretion of hormones which regulate appetite, from the gut. The increased drive to eat is a major contributor to the high rate of attrition in weight loss attempts and the failure of most individuals to maintain weight loss. Therefore, adopting strategies that help to control the physical drive to eat that occurs during energy restriction and weight loss, are key to improving adherence to the diet plan for weight loss. Two such strategies commonly adopted to suppress the drive to eat are diets that induce ketosis and appetite suppressant drugs (pharmacotherapy). I shall be discussing the ketogenic diets in a subsequent post.
2. Customising diets to food preferences – While controlling the drive to eat maybe a key target for improving adherence to a dietary intervention for weight loss, adherence to a diet plan for weight loss is also influenced by factors other than physical hunger. These include food preferences, cultural or regional traditions, food availability, and food intolerances. The similarity of a dietary intervention to a person’s usual diet has an important bearing on the level of adherence. For example, if the staple diet of a person includes large amounts of red meat, then telling him to switch over to a largely vegetarian diet because red meats have high amounts of saturated fats will likely have compliance issues. Instead, encourage him/her to reduce portion size and make small changes like choosing lean portions of meat and/or clearing as much visible fat as possible before cooking.
In a viewpoint article titled ‘A Call for an End to the Diet Debates’ published in The Journal of the American Medical Association in Aug 2013, the authors recommended – “Because behavioral adherence is much more important than diet composition, the best approach is to counsel patients to choose a dietary plan they find easiest to adhere to in the long-term.” However, while individualising a diet plan for weight loss according to a person’s habitual diet and dietary preferences, the diet plan should take into account a person’s nutritional requirements and be nutritionally sound.
3. Make changes gradually – When formulating a diet plan for weight loss, it is easier to make and sustain gradual changes to your eating habits rather than trying to revamp it overnight. Modest changes made over a period of time add up into a lifelong healthy eating habit. For example, one cup of whole milk contains 149 kcal, whereas the same quantity of fat-free milk contains only 86 kcal. If a person who normally consumes about a litre of whole milk daily switches to fat-free milk, in a year this will result in a reduction of caloric intake equivalent of 12 kg of body fat. Drinking fat-free milk rather than whole milk also significantly reduces intake of saturated fatty acids and cholesterol. To ensure long-term compliance with a diet, convenience of the individual in being able to follow that diet also needs to be considered.
Bottom line – “the only diet that can really work and ensure lifelong adherence is positively changing your eating habits for the rest of your life.
4. Self-monitoring of food intake – Another strategy for improving adherence to a dietary intervention is keeping a food record or ‘food diary’. Self-monitoring is the centrepiece of behavioural weight loss intervention programs. Maintaining a food record or food diary is common in both research and real-world settings for promoting and measuring adherence to dietary interventions, particularly for weight management. The main advantage of self-monitoring food intake is that it increases a person’s awareness of their food intake. In brief, to promote adherence to dietary interventions, clinicians should encourage individuals to self-monitor their food intake.
Best diet plan for weight loss
Keeping in view the twin targets of reduction in caloric intake and adherence to the diet in the long-term, diet plan for weight loss should be individualised, taking into consideration individual food preferences and health status, to achieve and maintain a reduction in caloric intake while maintaining nutrient adequacy. Three caloric reduction strategies, varying in energy goals can be adopted keeping in view the individual’s weight loss goals, based on the degree of obesity and associated comorbidities. These include – Reduced-Calorie Diets (RCDs), Low-Calorie Diets (LCDs) and Very Low-Calorie diets (VLCDs). However, here I will only be discussing the RCD as LCD and VLCD are primarily short-term strategies, designed often to give a jump-start in certain specific conditions; I will be discussing both these diets in a subsequent post.
The primary aim while formulating a diet plan for weight loss is to reduce the energy intake. The reduced-calorie diets, also known as reduced-energy diets (REDs), aim to produce a modest calorie deficit of 500 to 1000 kcal/day. If adhered to, these diets can lead to clinically meaningful weight loss. This type of diet plan for weight loss can be easily based, by and large, on an individuals’ usual diet pattern albeit with reduced portion sizes. However, as discussed above, while cutting down on calorie intake the diet plan for weight loss should be nutritionally sound. A meticulously maintained food diary will help identify the pattern and types of foods commonly consumed and changing to healthier alternatives where required. To eat a nutritionally sound and varied diet, with appropriately sized ‘portions’, follow the following basic guidelines:
- Eat a diet rich in fruits, vegetables and whole-grain foods.
- Limit saturated fats and trans fats in your diet to less than 7% and 1% respectively, of the total calorie intake. The intake of saturated fats can be reduced by eating low-fat alternatives like skim dairy products, lean cuts of meat (lean cuts of meat are nearly as low in saturated fat as dark meat of poultry), skinless poultry, and fish that has not been fried. Intake of trans fats can be reduced by substituting hydrogenated fats (e.g. stick margarine, shortenings) with liquid vegetable oils or tub margarine. However, it is important to know that dairy products do not need to be eliminated from the diet because skimmed or low-fat milk and dairy products are an excellent source of calcium and protein without excess saturated fat.
- Cut down snacking between meals.
- Choose low-energy-dense foods over high-energy-dense foods – ‘Energy density’ is the amount of energy or ‘calories’ in a particular weight of food and is generally presented as the number of calories in a gram (kcal/g). Foods with a lower energy density provide fewer calories per gram than foods with a higher energy density. Therefore, for the same number of calories, a person can consume a larger portion of food lower in energy density than a food higher in energy density; this helps to control the drive to eat. Evidence suggests that diets with a low-energy-density can help people maintain weight.
The energy density of foods is influenced by the composition of foods. Water lowers the energy density of foods because it has an energy density of 0 kcal/g and contributes weight but not the energy to foods. Fibre also has a relatively low energy density (1.5 to 2.5 kcal/g) and helps lower energy density. On the opposite end of the energy density spectrum, fat (9 kcal/g) is the most energy-dense component of food, providing more than twice as many calories per gram as carbohydrates or proteins (4 kcal/g). In general, foods with a lower energy density tend to be foods with either a high water content, lots of fibre or little fat. Examples of low-energy-dense foods include soups and stews, foods like pasta and rice that absorb water during cooking, foods that are naturally high in water (and also fibre), such as fruits and vegetables, and fibre-rich foods like whole-grains. Adding water-rich foods, such as vegetables, to dishes with high-energy-density, lowers the energy density of these foods. High-energy-density foods tend to include foods that are high in fats and/or sugars. Examples of high-energy-density foods include – fast food, sugar-sweetened beverages and fruit juices, confectionery and bakery products.
Thus, while people may consume about the same amount (weight) of food each day, it may differ drastically in terms of energy (or calories). So, it is feasible to consume less energy while at the same time achieving a greater degree of hunger control, by eating a lower energy density diet. In brief, by choosing the low-energy-dense food, you get to eat a lot more food for the same number of calories. To watch your portion sizes, to produce the required calorie deficit, portion-controlled diets are the best way to eat.
As highlighted above, to achieve and maintain a healthy weight, how much you eat is just as, if not more, important as what you eat. ‘Portion-controlled’ diets are the best way to ‘cut’ calories and eat healthy while continuing to eat the foods you enjoy. In addition to reducing calorie intake, this strategy also helps long-term compliance, which, as highlighted above, is an important determinant of the long-term success of diets for weight management. The strategy is a lot simpler than you may think.
To begin with, it will help to first understand what is a ‘portion’ and how it differs from ‘serving size’.
Serving size or simply serving is a specific and measurable amount of food or drink. Serving sizes are standardised to make it easier to compare similar foods in terms of their nutritional content. Different food-products have different serving sizes, which could be measured using home measures such as a cup (a cup of milk, for instance), or pieces, slices, or numbers (one slice of bread), or various standard measures such as grams or ml. An important application of serving-size is in the formulation of nutritional recommendations to help people know how much of different types of food they should eat to get the nutrients they need according to their age, weight, sex, physical activity etc. Depending on the above factors, ‘Recommended Dietary Allowance’ (RDA) may be more or less than a serving size. For example, serving size for fruits and vegetables is 100 gm and the nutritional guidelines recommend at least 2 servings of fruits and 3 servings of vegetables every day for an average healthy adult. Serving size is also used in ‘Nutrition Facts Label’ on packaged foods to depict the amount of food in the package in terms of the number of servings as well as the number of calories, proteins, fats, carbohydrate, cholesterol, sodium etc in each serving. As a packaged food may contain more than one serving, therefore, you will need to multiply the values per serving accordingly, to know the total caloric and nutritional content of a particular packaged food. Rules and regulations governing the requirement of Nutritional Facts Label on packaged foods vary from country to country.
A portion is the amount of food that you choose to eat for a meal or snack. Depending on how much you choose to eat, your portion size may or may not match the serving size. Some foods that most people consume as a single serving, actually contain multiple servings (e.g. a 600 ml bottle of soda). As highlighted in the preceding sections, too many calories, over your body’s requirements, can affect your weight and health. Therefore, along with choosing a healthy variety of foods, paying attention to the portion size is equally important while formulating a diet plan for weight loss; this will help you eat ‘just enough’ for you.
Some important tips to help you manage portions are given below. It is important to know that you won’t be required to measure and count everything you eat or drink, for the rest of your life; you only need to do it long enough to learn typical serving and portion sizes that are right for you.
- Use smaller plates/glasses – Using small-sized plates and glasses compared to normal dinner plates and glasses will give you a visual effect that it is full, while at the same time it keeps your portion sizes smaller. Remember, if you are still left feeling very hungry, you can always take a second helping.
- Layout your food away from the dining table – Instead of laying food on the dinner table, lay it away from the table, say in the kitchen itself. This way, you will think twice before you get up for a second helping. By giving yourself that ‘breather’, you may realise that you aren’t really hungry enough for a second helping after all.
- Stop eating and/or drinking when you are full – Though effort should always be to put only as much food in your plate as much you can eat, but keep in mind that if by mistake you have served yourself more than you need to eat, don’t feel guilty to leave it in your plate. By force-feeding yourself, to save yourself the feeling of guilt for wasting food, as is the conventional wisdom, you are not helping anyone, including yourself.
- Don’t eat out of the pack – It is advisable to buy snack foods in small packs, especially when there is no one to share it with you. However, if you are budget-minded and purchased a larger size packing because it offers more value for money, then don’t snack directly out of this pack, as there is a strong likelihood of you eating away the whole pack. Instead, put some snack in a bowl and put the rest of the packet away.
- Eat slowly – It usually takes up to 20 minutes for ‘signals’ indicating that you are full, to go from your stomach to your brain. So, if you are in the habit of eating fast, in this time you would probably end up eating way too much and completely stuff yourself. Instead, eat slowly; focus on what you are eating, chew your food well, and relish the taste and flavour of your food. This increases satiety. Taking small breaks in between to talk to your family members/friends sharing the dinner table with you, maybe a good idea. By giving yourself time to feel satiated, you may not even feel hungry enough for a second helping.
- Always eat sitting on a dinner table – Avoid eating in front of the TV, while driving or walking, or while you are busy with other activities. When you are not focussing on your eating, your brain may miss the signals for satiety, resulting in overeating.
- Eat regular meals – Have your meals regularly, as skipping meals, especially breakfast, generally leads to out-of-control hunger, which may cause you to overeat in your next meal.
- Don’t go to a party hungry – If you are going out for a party or to a restaurant, for a meal, where you will eat foods rich in calories, fats and sugar, it is advisable to eat a healthy snack before you leave home, to calm your appetite. Before daily meals also, it is a good idea to eat some salad or even drink a glass of water 10 to 20 minutes before you eat; this will add to the feeling of satiety and help you to consume less food.
- Avoid buffets – It is much harder to practice portion control when it is “all-you-can-eat” like in a buffet. Avoid them altogether if you do not have the willpower to limit the amount of food you eat. Remember, self-control plays an important role in the portion-controlled diet.
- Freeze excess food – If you make too much food, freeze food you won’t serve or eat right away. That way, you won’t feel tempted to finish the whole stuff.
- Resist the “upsize” offer – Its become a common marketing strategy, especially in fast-food restaurants, to offer larger sized meals for only a small amount of extra money. Although getting the super-sized meal for a little extra money may seem like a good deal, you end up with more calories than you need for your body to stay healthy. Therefore, before buying such “value meals” be sure you are making the best choice not only for your wallet but for your health too.
Gradually increasing portion sizes in the last two decades or so have led to changes in the thinking of people about a ‘normal’ at home too. A phenomenon called “Portion Distortion.”
Bottom line – “eat wholesome, nutritious food while restricting the total calorie intake.”
Estimating calorie deficit
As highlighted above, losing weight requires achieving a state of negative energy balance. Simply stated, to lose weight, you need to eat fewer calories than your body burns each day, forcing the body to burn fat stored in the body to meet the energy shortfall between calorie intake and output. It seems simple enough. However, what’s not so easy is doing it. The moot question is, when following a diet plan for weight loss, how do you know if you are eating fewer calories than your body burns?
Mathematically speaking, first, calculate the number of calories your body needs to maintain your current weight (i.e. your current Total daily Energy Expenditure [TDEE]); thereafter choose the size of the ‘calorie deficit’ you are aiming to achieve the desired rate of weight loss. Subtracting the planned calorie deficit from TDEE gives you the daily ‘calorie target’ you need to consume. Finally, measure the calorific value (amount of energy available from an item of food when digested) of your meals and, if necessary, make the required changes to bring the calorific value of the meal to the desired level. However, in practice, it is a lot more cumbersome. Here, first I will briefly discuss the common methodology used to estimate both the TDEE and calorific value of the meal, and the limitations of these methods.
Estimation of TDEE
The estimation of TDEE and estimation of physical activity, an important component of TDEE, in free-living individuals is extremely important in the context of various lifestyle diseases, including obesity. The estimation of TDEE allows estimating the total energy (calorie) requirement for the individual during nutrition support. TDEE refers to the total amount of energy expended during the 24-hour period and there are three components to your TDEE.
- Basal Metabolic Rate (BMR)
- Diet-Induced Thermogenesis (DIT)
- Activity Thermogenesis (AT)
Basal Metabolic Rate (BMR) – Also referred to as basal energy expenditure (BEE), is the amount of energy required to maintain the basic bodily functions, at rest, by an individual in a fasting state, in a thermo-neutral environment (maintenance of the ambient temperature within 0.50 C of the body temperature, to avoid heat and cold stress and to optimize energy use and oxygen consumption). However, in routine practice, another measure, Resting Metabolic Rate (RMR) or resting energy expenditure (REE) is used; it is measured under less strict conditions and its value is slightly higher than BMR.
RMR is the largest component of TDEE and accounts for about 60 to 75% of the TDEE; consequently, it has the largest impact on the energy balance equation (as defined by Food and Agriculture Organization [FAO], an agency of the United Nations, energy balance is achieved when ‘input’ [or dietary energy intake] is equal to output [or expenditure], plus the energy cost of growth in childhood and pregnancy, or the energy cost to produce milk during lactation) and ultimately on the bodyweight maintenance.
RMR is determined by several factors, including age, gender, body size, body composition, ethnicity, physical fitness level, hormonal status, and a range of genetic and environmental influences. In the context of weight-loss diets, an important factor which also impacts RMR is the energy-restricted diets; efforts to lose weight by restricting energy intake leads to a decrease in the REE, which is more than what can be explained by the loss of the body mass. As a result of the large number of varied factors influencing RMR, there is a great degree of inter-individual variation in the RMR; maybe to the tune of almost two and a half times.
Diet-Induced Thermogenesis (DIT) – Also known as the thermic effect of food (TEF). Following ingestion of food, there is an increase in the energy expenditure of the body, over and above the RMR, as result of the energy required for the food digestion, absorption, transportation and metabolism, storage of nutrients and elimination of waste. This increase in energy expenditure, over and above the RMR, which persist for several hours after ingestion of a meal, is known as diet-induced thermogenesis. The magnitude of DIT is determined by the quantity and the type of food. Even though it is the smallest component of TDEE, estimated as about 10% of the TDEE, it could play a role in the development and/or maintenance of obesity in the long-term.
Activity thermogenesis (AT) – Also, known as Activity Energy Expenditure (AEE); it is the energy expenditure incurred during physical activity and/or exercise. It has two components – Exercise activity thermogenesis (EAT) and Non-exercise activity thermogenesis (NEAT), which includes energy expenditure of all physical activities other than volitional sporting-like exercise and includes both occupational and leisure activities. AEE is the most variable component of TDEE; in sedentary individuals, it can account for less than half of the REE while in competitive athletes or heavy labourers, it can be as high as 1 to 2 times the REE. The main factors influencing AEE include intensity, duration and frequency of the physical activity/exercise.
Assessment of physical activity and TDEE
Many methods are available for assessing physical activity and energy expenditure. Some commonly used methods include – Doubly Labeled Water (DLW) technique, Calorimetry (both direct and indirect), accelerometry, heart rate monitoring, pedometry and self-report methods. Of these, DLW and calorimetry techniques are highly accurate methods for assessment of TDEE. However, these methods are expensive and have limited availability, hence these are primarily used only for research purposes.
Heart rate monitoring is a relatively low-cost technique and exercise heart rate estimates energy expenditure with reasonable accuracy; however, it estimates energy expenditure only for aerobic activities. Though heart rate to estimate energy expenditure appears practical, there are several limitations. First and foremost, to be able to predict energy expenditure, first, a graph needs to be plotted between heart rate and oxygen consumption in a laboratory, using indirect calorimetry. Finally, factors other than oxygen consumption influence exercise heart rate response and distort the relationship between exercise heart rate and oxygen consumption and thus impact the accuracy of estimation of energy expenditure, based on heart rate. These factors include environmental temperature, emotions, previous food intake, muscle groups exercised, body position, continuous or discontinuous (stop-and-go) activity or whether muscles act statically or more dynamically.
Accelerometry and pedometry can help to measure physical activity levels, however, both these methods are inaccurate for estimation of energy expenditure. Self-reports also have low accuracy and reliability. Apart from the various modalities for measurement of energy expenditure, discussed above, a large number of prediction equations for estimation of REE and norms for energy expenditure during common physical activities are also widely in use. However, keeping in view the number of factors, including genetic, which influence REE and the wide inter-individual variations in REE, the predicted REE values using these equations are at best only an approximation. Similarly, the prediction of AEE using the norms for various activities as well as physical activity levels are at best only averages. Furthermore, such norms are available only for aerobic activities, and not for anaerobic activities like strength training, which is an important component of any physical training program.
The above discussion aims to highlight the limitations and drawbacks of various methods used to assess energy expenditure in clinical settings. The approximation of energy expenditure using the above methods will introduce an error of at least a few hundred kcal, which is very significant when the calorie deficit planned to induce weight loss is itself a few hundred kcal.
Measurement of the calorific value of foods
Determining the energy content of food depends on the following:
- The components of food that provide energy, viz. carbohydrate, fat, protein and alcohol should be determined by appropriate analytical methods.
- The quantity of each food component must be converted to food energy using ‘energy conversion factors’ that express the amount of energy available per unit weight of each food component.
- The food energy of all food components is then added together to give the total nutritional energy value of the food.
Estimation of the calorific value of foods
A variety of different energy conversion factors for foods have been developed since the late nineteenth century. The Atwater general factor system, developed by W.O. Atwater and his colleagues, at the end of the 19th century is one of the most widely used, in part because of its simplicity. He used a single factor for each of the energy-yielding nutrients, regardless of the food in which it is found. The energy values are 4.0 kcal/g for protein, 9.0 kcal/g for fat and 4.0 kcal/g for carbohydrate. He used a factor for alcohol with a rounded value of 7.0 kcal/g. These average net values, rounded to whole numbers, are referred to as Atwater general factors and are used to estimate the intake of food energy in nutrition practice.
Practical considerations in calculations of the energy value of foods and diets Calculations of energy intake, using energy conversion factors, though convenient to use, is likely to be associated with some inaccuracies, as a result of the following reasons:
- Variations in food composition: Foods are biological mixtures and as such show considerable variation in composition, particularly in respect of water and fat content. This means that compositional values quoted for representative samples of foods in food composition tables are averages and do not necessarily apply to individual samples of foods. In studies where great accuracy is required, samples of the food consumed must be analysed.
- Measurements of food intake: In estimating energy intakes, measurements of food intake are made, and these are known to be subject to considerable uncertainty. Even in studies under very close supervision the errors in weighing individual food items are rarely less than ±5%. A certain degree of pragmatism must, therefore, be used when assessing procedures for calculating energy intakes, and many authors impute greater accuracy to quoted calculated energy intakes than is justifiable.
- Individual variation: Variations in individuals are seen in all human studies, including digestive efficiency, and these variations are not allowed for in most calculations.
As a result of the inaccuracies in the estimation of calorific value of foods, there will again be an error of at least a few hundred kcal, which, as discussed above, is very significant when the calorie deficit planned to induce weight loss is itself a few hundred kcal. Furthermore, small differences in energy intake add up over time and result in significant changes in body weight. So, what does this mean for us? The above discussion reveals the inherent limitations in estimating the energy intake from foods while formulating a diet plan for weight loss using the Atwater general factor system or food tables. The current system, at best “provides only an estimate of the energy content of foods.” Though this may be a guiding factor in helping consumers make good or bad food choices (low and high-calorie foods), but is not of much practical value in planning individual diets of certain caloric value for weight management.
How do I know when I am in a calorie deficit, and by how much?
In the backdrop of the inadequacies of the methods to assess both the energy expenditure as well as the energy intake, a pertinent question that crops up in the mind of everyone following a diet plan for weight loss is how do they know when they are in a calorie deficit state and by how much?
Unfortunately, there is no definitive way to know if you are in a calorie deficit and more so by how much. The conventional logic says that if there is a calorie deficit, one should lose weight and the degree of weight loss should reflect the size of the calorie deficit. To understand, if this logic works in a real-life situation, it will help to first understand the process of weight loss.
As has been highlighted more than adequately that ‘the fundamental principle of nutrition and metabolism states that an imbalance between the energy intake and energy expenditure is associated with a change in body weight, which is accounted for by a gain or loss of body fat and lean tissue, which generally change in parallel. Therefore, the aim of all interventions for the management of obesity, whether in the form of a diet plan for weight loss, exercise, drug therapy, bariatric surgery, or any combination of these, is to tip the balance between energy intake and expenditure. However, weight loss is not as simple as eating less and exercising more. Even though this energy balance principle looks simple, calculation of the dynamics of energy imbalance and translation of the imbalance to predict a change in body weight is not straightforward.
To begin with, let us look at the mathematics of weight change. This is based on the energy equivalents of fat stored in the adipose tissue. As has been highlighted earlier, adipose tissue is a storage site for fat in the body. Each one pound (454 g) of adipose tissue contains about 86% fat or about 390.4 g; the remaining 14% of adipose tissue mass comprises largely of water, protein, carbohydrates, and minerals. Since 1 g of fat provides 9 kcal of energy, the energy content of one pound of adipose tissue is about 3500 kcal (390.4 X 9 = 3514 kcal). Based on this calculation, one of the most pervasive weight loss rules, advocated by various health and nutrition organisations, states that a cumulative energy deficit of 3500 kcal is required to lose one pound (or 7700 kcal to lose one kg) of weight. This rule is commonly known as ‘static model for weight loss’ or ‘3500 kcal per pound’ rule. Following this rule, if daily calorie intake is reduced by just 100 kcal and energy output is increased by 100 kcal through exercise, in a year this will lead to a calorie deficit of 73000 kcal (365 X 200 = 73000). Using the energy equivalent of fat stored in adipose tissue, this calorie deficit will lead to a loss of about 9.5 kg (or 21 pounds) of body fat in a year (73000 ÷ 7700 = 9.48).
However, new research suggests that this rule grossly overestimates actual weight loss. The biggest flaw with the 3500 kcal per pound rule is that it does not take into account the reduced energy expenditure as a result of the weight loss and assumes that weight change from any intervention is cumulative and will continue linearly over time. However, in actual practice, this is not true as that is not the way the body responds. The human body is a very dynamic system, and a change in one part of the system always produces changes in other parts. Any reduction in body weight results in dynamic physiological adaptations that lead to a reduction of both the resting metabolic rate (RMR) as well as the energy cost of the physical activity i.e. the Activity Energy Expenditure (AEE), leading to slowing down of the process of weight loss. As a result, even when perfect adherence to intervention is followed, it is generally acknowledged that weight change will slow over time due to these passive compensatory changes in energy expenditure that occur with the weight loss. Thus, a small initial decrease in energy intake sustained over many years cannot lead to large weight loss, as is often claimed.
As a consequence of the gradual slowing down of the weight loss process, in spite of sticking to the diet plan for weight loss, the whole process of weight loss can be broadly divided into two distinct phases – a rapid weight loss phase, lasting several days or weeks, followed by a slower weight loss phase lasting up to two years. Apart from the passive compensatory changes, alteration in the composition of the weight lost also contributes to the weight loss process. In the early rapid weight reduction phase, the body largely utilises the glycogen (the storage form of carbohydrates in the body) stored in the body to meet the energy deficit created by food restriction. However, when glycogen is stored, every gram of glycogen is accompanied by storage of approximately 3 g of water. When the glycogen is used as fuel, the water stored with it is also released. Thus, if the body uses 500 g of glycogen, it will lose about 1500 g of water stored with it; together this will show up as a loss of 2 kg on the weighing scale. Also, glycogen contains fewer calories (1 g of carbohydrate is equal to 4 kcal) per gram compared to fat (equals 9 kcal/g); as a result, a larger amount of glycogen will be needed, compared to fat, to provide the equivalent energy. As a result of the combined effect of both these factors, in the early rapid weight loss phase, the body loses more weight for a given calorie deficit. Simply stated, though a calorie deficit of 7700 kcal is the energy equivalent of one kg of body fat, in the early rapid phase considerably more than one kg would be lost for the given calorie deficit as the body uses a larger proportion of glycogen in the early phase of weight loss. As a result, short periods of calorie restriction often encourage the dieter; however, water and glycogen constitute a larger proportion of the weight lost with only a small decrease in body fat. As had been highlighted in the preceding sections, the body has limited stores of glycogen. As the reduction in energy intake is maintained over time and the body continues to lose weight, a progressively larger proportion of fat in adipose tissue is utilised to meet the energy deficit created by restricted food intake.
The compensatory reduction in energy expenditure, discussed above, is the result of changes in the three processes – reduced Resting Energy Expenditure (REE), Activity Energy Expenditure (AEE), and Thermic Effect of Food (TEF). The REE is reduced secondary to loss of lean and fat mass, AEE is reduced due to decreased cost of moving a reduced body mass and TEF is reduced due to lower intake of food and reduction in protein turnover and its associated energy cost. The net effect of these compensatory changes is a progressively slower rate of weight loss, in spite of following the same diet plan for weight loss, leading into the second slower weight loss phase. This phase extends for months or years. Gradually, at some point weight loss will be imperceptible, and eventually, cessation of weight loss occurs when energy equilibrium is restored at a new lower level. To reach a stable weight plateau often takes months or even years. Over this period the energy content of weight change (i.e. energy deficit required to produce a specified weight loss) is not constant at 3500 kcal/pound but is changing over time. During the early rapid weight loss phase, values are substantially less than 3500 kcal per pound and then as the composition of weight loss changes, values approach 3500 kcal per pound (or 7700 kcal per kg) during the second slower weight loss phase. In simpler terms, it can be stated that people require a different calorie deficit to lose a single pound, depending on their current weight; this means that if you are trying to lose a large amount of weight, the caloric deficit required to lose weight is going to be different for the last 10 kg then it was for the first 10 kg. Both fat and lean tissues are lost and do so in a predictable way as the body remodels to a new weight loss plateau. Over time, energy deficit will need to be constantly revised to maintain the process of weight loss, i.e. after the weight loss plateau is reached, you will have to cut more calories. This new calorie deficit will again follow the same cycle of weight loss. Thus, when people try and lose weight, the weight loss does not necessarily follow a straight line; conversely, as weight drops and a new equilibrium is introduced, weight loss plateau occurs and it takes a further revision of calorie intake to create a new calorie deficit to move out of that equilibrium and back down again.
This dynamic equilibrium of body weight (cycle of weight loss) can be illustrated as below:
In the above background, when following a diet plan for weight loss, the most appropriate strategy to assess calorie deficit would be to meticulously maintain a food and exercise diary and weekly monitoring of body weight on a good weighing scale (preferably one which measures weight in gradations of 100 gram; take care to ensure that you use the same machine every time and that it’s periodically calibrated). As you achieve the desired calorie deficit, you will, for sure, start to lose weight. However, as highlighted above, after a variable period pace of weight loss will start to slow down and then plateau off as a result of the various compensatory changes discussed above. However, as the process of slowing down of weight loss starts, take care to review your dietary intake and physical activity levels also, and carry out necessary corrections in case your dietary intake and/or physical activity levels have been compromised. However, do remember that the weight loss will continue, albeit at a slower pace, in consonance with the calorie deficit, as long as the calorie deficit between the energy intake and energy expenditure is maintained.
Once the goal body weight has been achieved, either shift to the weight maintenance phase, or in case further weight loss is desired, take a re-look at your energy balance equation and start all over again by creating a new calorie deficit. However, as you attempt to make changes to your diet plan for weight loss to create further calorie deficit, the increasing impact of hunger would be a limiting factor in adherence to the dietary intervention. In this scenario, exercise assumes greater significance as a means to increase energy expenditure and thus the calorie deficit.
A confounding factor in the slowing down of weight loss is the increase in muscle mass, in response to a strength training program, in case one is regularly engaging in. Taking into consideration all of the above, monitoring body composition along with bodyweight would be the best way to monitor the outcome of weight loss efforts. In the absence of any weight loss (maybe even increase in body weight), if the body fat % has reduced and lean body mass has increased, than the diet plan for weight loss in conjunction with exercise, would count as successful, rather more desirable, outcome of weight loss efforts despite there being no change, or an increase, in the bodyweight. However, high cost and limited availability of equipment (such as DEXA scan), is a limiting factor.
Is there anything sacrosanct about the calorie deficit size of 500 to 1000 kcal?
It is natural for anyone following a diet plan for weight loss to want to lose it very quickly. However, evidence shows that rapid weight loss has various undesirable effects on the body. First and foremost is its effect on the composition of the weight lost. Though the central goal of obesity treatments is to lose maximum fat while trying to preserve lean tissue (i.e. fat-free mass [FFM]), some proportion of the weight lost will, however, comprise of lean tissue. The excessive loss of lean tissue poses a range of clinical risks. The proportion of weight loss as lean tissue, is not constant but varies over time and is determined by multiple factors including level of energy intake, diet composition, sex, baseline adiposity, the presence of inactivity or type and level of activity added, the subject’s metabolic state or hormonal response and phase of weight loss, with larger changes observed early during the weight-loss period.
A widely cited rule, “Quarter FFM Rule”, gives approximate estimates of the lean tissue lost as a proportion of the total weight loss. According to this rule, approximately one-fourth of weight loss is FFM while the remaining three-fourths is fat mass. With a moderate restriction of calorie intake, the proportion of weight loss as fat is more; in contrast, when rapid weight loss is attempted with more severe energy restriction, the proportion of weight loss as lean mass is more. The second effect of the pace of weight loss is on weight maintenance following weight loss. Individuals who lose weight more rapidly by creating larger energy deficits, tend to regain more weight compared to those who lose weight at a slower rate. Finally, rapid weight loss leads to some health hazards including increased risk of gallstone formation, loss of bone mass and acute attack of gout. Given the above, a reasonable and safe rate for weight loss is about half- to one kg (1 to 2 pounds) per week. A calorie deficit of 500 kcal/d would lead to a cumulative deficit of 3500 kcal in a week which is calorie-equivalent of 1 pound of adipose tissue.
Say NO to Fad diets
In general, our beliefs about food are highly irrational and when we are struggling with weight, we want a magic pill, or in the least, a diet plan for weight loss that’s a functional equivalent of a pill. Above, I have discussed the problems people face to successfully maintain the weight loss in the long-term. As highlighted above, the dieting industry feeds off our anxieties about weight, our failure to stick to diets and successfully lose weight. The diet dreams are splashed across magazine covers and blare from the TV, offering tips and tricks, that will, readers and viewers are promised, make weight loss easy and fast. One of the most popular fad diets, the ketogenic diet, commonly known as the keto diet is promoted online and in the media as a weight-loss wonder and seemingly all-round magical healer. It will be discussed in detail in my subsequent post. As a result, people are more susceptible to adopt various fad diets that claim to aid in losing weight very fast.
The British Dietetic Association (BDA), in the article Food Fact Sheet: Fad diets, defines a fad diet as “A fad diet is the kind of plan where you eat a very restrictive diet with few foods or an unusual combination of foods for a short period of time and often lose weight quickly. However, most people then get fed-up with the restrictions, start eating more, chose less healthy foods and pile the pounds back on”. It further states – Many of us would like to lose a few pounds. However, you shouldn’t be tempted by the ever-increasing range of ‘quick fix’ and ‘miracle’ options making unrealistic weight-loss promises for minimum effort. Sadly, there is no magic solution to losing weight and keeping it off long-term. There is no wonder diet you can follow without some associated nutritional or health risk and most are offering a short-term fix to a long-term problem. You can read in details about fad diets in my post Say NO to Fad Diets.
As has been highlighted above, diet plan for weight loss should be individualised taking into consideration individual food preferences to achieve and maintain a reduction in calorie intake. In her book, Calories and Corsets: A History of Dieting over 2000 Years, referred to above, Foxcroft correctly argues that the “repetitive and often unsatisfying experience of dieting can only be debunked by a long, hard look at its history, a process that could release us from the tyranny of fads and quick-fixes”. We need to think a little more about what’s really getting between us and a healthy lifestyle in the long term, instead of seeking out quick and unsustainable fixes. The best way to lose weight and keep it off is to make healthier choices, eat a nutritionally balanced and varied diet with appropriately sized portions and be physically active. I conclude with a suggestion to take a good look at the ancient Greek philosophy of diaita.