Say NO to Fad diets


The world is in the grip of an obesity epidemic; additionally, a “fad diet” industry has arisen. Worldwide obesity has tripled since 1975. It is a chronic and multifactorial disease and one of the most important causes of morbidity and premature mortality worldwide. 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.

The image depicts fronts covers of various diet books with a caption 'Say No to Fad Diets'.
Some popular fad diets.

In my post Diet Plan for Weight Loss – It is going to be a journey, I had discussed in detail, the dietary interventions for the management of obesity. However, 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. In my post Diet Plan for Weight Loss, referred to above, I had discussed the issue of weight loss and regain and had highlighted that due to the strong physiological tendency to regain weight, long-term weight loss maintenance remains the main challenge of obesity treatment. Another important aspect that I had discussed in this post was the dramatic disparity between the patient’s expectations from a weight loss regimen and the professional recommendations or reasonable weight loss that can be accomplished and maintained in most cases. The patient’s frustration and anxiety arising as a result of the gulf between the patient’s unrealistic expectations and professional recommendations have been exploited up to the hilt by the dieting industry.

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. As a result, people are more susceptible to adopt various fad diets that claim to aid in losing weight very fast. This is evident from the fact that an estimated 1000 weight-loss diets have been developed with more appearing in the lay literature and the media regularly. 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 would not be facing an obesity crisis. However, despite its failure to provide that illusory ‘magic pill’, which most people struggling with their weight woes have been seeking, a spurt in the epidemic of obesity in the last few decades has created a massive diet industry. By constantly profiting off millions of people’s weight woes, the dieting industry has flourished and burgeoned into a multi-billion dollar industry. 

So, my honest endeavour, on my blog, has been to educate people about the scientific aspects of weight loss and maintenance in the long-term on the road to attain holistic health. In this series on dietary interventions for weight loss and maintenance, in my post Diet Plan for Weight Loss referred to above, I have dealt at length with various aspects of weight loss and maintenance, including setting realistic targets for weight loss, the all-pervasive issue of weight regain, important determinants of the outcome of a diet plan for weight loss, and most importantly, a diet plan for weight loss which you could adhere to in the long-term while continuing to eat healthily and eating foods you enjoy. In my post, Very Low-Calorie Diet – All You Need to Know, I had discussed a diet plan backed by decades of medical research, which can be used to give a ‘jump-start’ to a weight loss program in cases of severe obesity and/or in the presence of significant co-morbidities, which are likely to improve with weight loss. In my post, Keto Diet – Debunking the Myth, I have dealt with the Keto diet, a fad diet, exclusively, keeping in view its current popularity. Finally, in this post, I shall be discussing various fad diets in detail, including tips to identify a fad diet, some popular fad diets, and their ill-effects on health.

What is a fad diet?

According to the Centre for Disease Control and Prevention (CDC), the leading national public health institute of the United States a fad diet is any diet that promises fast results and represents only a short-term dietary change. But according to the CDC, fad diets can limit nutritional intake, are unhealthy, and always seem to fail in the long run. The American Heart Association (AHA) has declared war on fad diets. In an article titled Don’t be Had by Diet Fadspublished in the ‘Heart Insights’, a free digital-only magazine of the American Heart Association, in Spring 2017, it states – Quote – “Quick-weight-loss or “fad” diets can seem appealing. We like the idea that we can slim and trim with very little time or effort. Some weight-loss diets may work in the beginning. This is often because the fad diet helps you cut calories in one way or another. But many of these diets restrict certain food groups or promise unrealistic results. They are hard-or unhealthy-to sustain over time. They do not help you develop a healthy relationship with food. As soon as you go back to your usual eating habits, the weight may start piling back on. This often leads to “yo-yo’ dieting: losing and regaining weight over and over.” Unquote. It further states – There is no magic formula for losing weight other than taking in fewer calories than you burn. The key is to find a healthy daily eating pattern that keeps you at a healthy weight and provides the right balance of calories and nutrition with appropriate amounts of regular physical activity. This will almost always mean changing your behaviour and making a lifestyle change.

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 should not 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.

Role of doctors in promoting fad diets

Unfortunately, apart from the media and peers, who contribute to the popularity of fad diets, in case of many patients, doctors who haven’t embraced nutrition as a viable treatment option may be the reason why these patients turn to fad diets. A lot of doctors tell their patients that they need to lose weight but not how. In the end, patients become frustrated and turn to their own solutions.

How to identify a Fad diet?

In the ‘Article Don’t Be Had by Diet Fads’, referred to above, the AHA lays down criteria to recognise a fad diet, as under:

  • Promises “miracle” foods that burn fat.
  • Requires you to eat unusual amounts of only one food or food type, or to eat specific foods in certain combinations.
  • Requires rigid menus of a limited number of foods to be eaten at a specific time of the day.
  • Promises rapid weight loss of more than two pounds a week.
  • Does not warn those with diabetes or high blood pressure to seek medical advice before starting the diet.
  • Does not include energy balance and increased physical activity as part of the weight-loss plan.
  • Does not help you make the transition from weight loss to weight maintenance.

Besides, the BDA lays down criteria to spot bad dietary advice. It states – ‘It can be useful to be aware of misleading weight-loss claims, so you don’t end up wasting your time, effort and money and even risk your health. How can you tell dieting fact from fiction? Stay away from diets that:

  • promise a magic bullet, ingredient, or product to solve your weight problem without having to change your lifestyle in any way
  • promise rapid weight loss of more than 2 lbs of body fat a week
  • recommend magical fat-burning effects of foods (such as the grapefruit diet) or hidden ingredients in foods (the coffee diet)
  • promote the avoidance or severe limitation of a whole food group, such as dairy products or a staple food such as wheat without any medical reason to do so (and suggest substituting them for expensive alternatives, special products or large doses of vitamin and mineral supplements)
  • promote eating mainly one type of food (e.g. cabbage soup, chocolate, or eggs) or avoiding all cooked foods (the raw food diet)
  • recommend eating foods only in particular combinations based on your genetics or blood type
  • suggest being overweight is related to a food allergy or a yeast infection
  • recommend ‘detoxing’ or avoiding foods in certain combinations such as fruit with meals
  • offer no supporting evidence apart from a celebrity with a personal success story
  • are based on claims that we can survive without food or having liquid meals only
  • focus only on your appearance rather than on health benefits
  • are selling you products or supplements
  • recommend eating non-food items such as cotton wool
  • make recommendations based on a single study
  • recommend the same diet for everyone without accounting for specific needs
  • based on a ‘secret’ that doctors are yet to discover

Remember, if it sounds too good to be true – it probably is.

Popular fad diets

Fad diets are not a new phenomenon. The market for weight loss diets arose with industrialization, a time during which food became a commodity. In the early 19th century, Lord Byron, who was a poet, advocated vinegar as a remedy for obesity, as it reduced his appetite; however, it has been suggested that Lord Byron apparently suffered from anorexia. Jean Anthelme Brillat-Savarin, a French lawyer, politician, and author of a celebrated work on gastronomy, Physiologie du gout (“The Physiology of Taste”), originally published in 1825, blamed refined flour and starch for obesity and recommended a low carbohydrate, high protein diet for weight loss. William Banting (1796–1878) is known for being the first person to promote the benefits of a low-carbohydrate diet, long before the Atkin’s diet and the rush of low-carb diets that followed. Banting was neither a doctor nor a nutritionist but was a Victorian undertaker. He suffered from obesity, and based on the success of his diet plan, suggested to him by his physician, in 1863 published a booklet, “Letter on Corpulence Addressed to the Public”, wherein he counselled the overweight and the obese to limit the intake of carbohydrates, especially those of a starchy or sugary nature. Perhaps, the most dangerous fad diet was the ‘smoking diet’, which was made famous in the early 20th century, based on the knowledge that nicotine could reduce appetite and influence an individual’s eating habits. For decades tobacco companies employed the connection between slimness and smoking in their advertisements, mainly in brands and advertisements targeting women. Although fad diets are ever-changing, most can be categorised in these general groups:

Fad diets based on the manipulation of macronutrient content

Majority of the fad diets are based on the manipulation of the macronutrient contents in the diet. The name of the macronutrient focused diet is usually based on the one macronutrient that is targeted for change. However, what needs to be recognised about macronutrient-focused diet prescription is that when the proportion of one macronutrient is altered, there will automatically be a change in the proportion of the other two macronutrients. Carbohydrate is the most commonly targeted macronutrient.

The more traditional modern diets contained high amounts of carbohydrates, standard amounts of proteins, but low amounts of fat. Many people experienced failure in achieving and maintaining weight loss using these diets. The apparent reason for the failure of these diets to induce weight loss was that since these diets were low-fat, people misinterpreted this and thought they could eat as much ‘low-fat’ food as they desired and still lose weight. However, the fact which they did not understand, is that it is not merely the total fat content of a diet, but rather the total energy content, which determines the success of a diet to induce weight loss. Based on the macronutrient content, some of the popular fad diets can be categorised into the following main categories:

a. Very-low-carbohydrate, high-protein, high-fat fad diets

The broad macronutrient composition of these diets is – Proteins 25 to 30%, carbohydrates 5 to 15% and fats 55 to 65%. They are concomitantly high in saturated fats. As discussed earlier, these diets give rise to ketosis. The two internationally popular diets in this category are the Atkins and the Protein Power diets.

b. Reduced-carbohydrate, high protein, fat-restricted fad diets

The broad macronutrient composition of these diets is – Proteins 25 to 35%, carbohydrates 35 to 50% and fats 20 to 30%. The two internationally popular diets in this category are the ‘Zones’ and ‘Sugar Busters’.

c. High-carbohydrate, Low-fat, fad diets  

Ornish, Pritikin diet, LEARN (Lifestyle, Exercise, Attitude, Relationships and Nutrition)

d. Low-carbohydrate, High-Fat fad diets  

Ketogenic diet

Fad Diets based on the restriction of specific foods or food groups

The most well-known fad diet in this category is the Palaeolithic diet, also called the Paleo diet. It is based on everyday foods that mimic the food groups of our pre-agricultural hunter-gatherer ancestors. The diet only includes foods that were available to hunter-gatherers, such as meat, nuts, healthy oils and fresh fruits and vegetables. Cereal grains, legumes, dairy and other processed/refined products are excluded.

Formula fad diets

These diets are based on dietary supplements and are very-low-calorie diets. These include Slim-Fast and Bernstein.

Fad diets based on the manipulation of the timing (i.e. fasting)

Most weight control programs use a continuous (daily) calorie restriction. However, more recently the manipulation of timing, namely intermittent calorie restriction or intermittent fasting (IF) has received considerable interest as an alternative strategy. These dietary strategies involve abstaining from food and caloric beverages for a certain period alternated with normal eating.  Various IF regimens differ in the length and frequency of the fast cycle. To avoid persistent hunger, modified IF allows a small amount of food intake. The common types of IF include periodic fasting or 5:2 diet (2 days of fasting and 5 days of ad libitum eating during the week), alternate-day fasting (fast day alternated with ad libitum eating) and time-restricted feeding (ad libitum eating within specific windows (< 8 hours/day).

Health consequences of fad dieting

Fad diets have several harmful effects on health. Some of the important detrimental effects are as under:

1. Increased risk of cardiovascular diseases

A fad diet with a high content of fat is known to postprandially (after a meal) increase the risk of cardiovascular events as a result of the rise in the triglyceride-rich lipoproteins in the blood. The levels of lipids (derived from the Greek lipos, meaning fat) in the blood normally fluctuate during the day, in response to food intake. Lipids are a diverse group of organic compounds. Triglyceride, a type of lipid, is the most predominant lipid in the human body as well as in the diet, accounting for approximately 98% of the lipids in the diet. In the body, they are the principal lipids in the blood, where, being insoluble in water (blood plasma, the liquid part of the blood that carries various cells [red blood cells, white blood cells and platelets] various nutrients [glucose, proteins and fats etc] is mostly water [up to 95% by volume]), they are carried within the lipoproteins, such as low-density lipoproteins (LDL), colloquially known as bad cholesterol.  In addition to being derived from the diet, triglycerides are also synthesised endogenously by the liver. Lipoproteins are responsible for the distribution of cholesterol and triglycerides from the intestine and liver to the peripheral cells, where they are either broken down by the cells to provide energy or are stored within the adipose tissue for later use.

Postprandial lipemia

Following ingestion of a meal, expectedly there is a rise in the triglyceride-rich lipoproteins (TRL). This is a physiological and transitory event; in healthy people, blood plasma triglyceride levels peak 3-4 hours after the ingestion of a meal, especially fatty meal, and tend to return to baseline within 6-8 hours. Triglycerides are vital for health – providing key substrates in metabolic pathways and being a source of energy. However, excess fat consumption can induce a lipotoxic state, wherein peak in plasma triglyceride levels is 2-3 fold higher and prolonged: plasma triglyceride levels remain elevated up to 10-12 hours. The prolonged and increased levels of triglycerides and triglyceride-rich lipoprotein levels after a meal is known as postprandial lipemia.

Health effects of postprandial lipemia

Postprandial lipemia is a significant risk factor for cardiovascular diseases (heart diseases, stroke and peripheral artery disease) because of its role in atherosclerosis and endothelial dysfunction (Endothelial dysfunction [ED] can be defined as a disturbance to the vasodilatory [relating to the dilatation of blood vessels] response of the endothelium and impairment of its anti-thrombotic [preventing the formation of blood clots [thrombi] and anti-inflammatory functions. The impairment of the endothelial function eventually translates to the development and progression of atherosclerosis and its complications viz. cardiovascular diseases). This has serious implications because nowadays the common dietary habit is characterised by high-fat content and high frequency of meals; hence most individuals spend the majority of the day, approximately 18 h, in postprandial (fed) state, resulting in frequent and prolonged exposure to high lipid levels.

Numerous prospective case-control studies (wherein participants are enrolled in the study before they develop the disease or outcome in question) have qualitatively established postprandial triglyceride as a risk factor for cardiovascular diseases.

Factors affecting postprandial lipemia

The postprandial lipemic response is modulated by several factors, including background dietary pattern (i.e. habitual diet) and meal composition, lifestyle conditions (physical activity, smoking, alcohol consumption), physiological factors (age, gender, menopausal status), and pathological conditions (central obesity, diabetes mellitus, insulin resistance and hypertriglyceridemia [a high level of triglyceride levels in the blood]). Besides, genetic factors may also affect the postprandial lipemic response. Though these above-mentioned factors do influence postprandial lipid response and metabolism, their effect on the lipemic response is variable. Amount of fat in the meal and pre-existing hypertriglyceridemia have the most potent effect. Even though all the other factors mentioned above also have a significant impact, however, here the discussion will be limited only to meal size and composition.

Meal size and composition

Among the various factors that modulate postprandial lipemia, diet plays a significant role. Postprandial lipemia is influenced by meal size as well as meal composition, in particular by fats, carbohydrates, fibres and proteins. However, a high-fat meal, in comparison with a high-carbohydrate meal or a standard meal, is most deleterious in terms of postprandial lipemia and endothelial dysfunction.

Dietary fat

Both the amount and type of fat in the fad diet influences postprandial lipemia.

Fat amount

The fat content of a meal influences the postprandial lipemic response: increasing amounts of fat increase postprandial triglyceride levels. A very low (5 g) or low (15 g) dose of dietary fat does not significantly increase blood triglyceride levels postprandially; moderate doses (30-50 g) increase postprandial triglyceridemia in a dose-dependent manner, i.e. blood triglyceride levels increase with an increasing amount of fat in the diet, and finally very high doses (80 g and above) exaggerate postprandial triglyceridemia but without dose-dependence. Despite the known effects of high-fat diets on postprandial lipemia and its effect on cardiovascular diseases, fad diets high in fats have been popular among people looking for quick fixes to their weight problem. According to the award-winning historian Louise Foxcroft, author of the book Calories and Corsets: A history of dieting over two thousand years, in 2003, one in every 11 Americans was following the Atkins diet, a prototypical low-carbohydrate, high-fat diet, which contains fats in the range of 55-65%. At the same time, Atkins books have sold over 45 million copies.

Fat types

Postprandial lipemia is not only modulated by the fatty acid composition of the meal, but also by the fatty acid composition of a subject’s usual (i.e. habitual) diet. Results of various studies have shown that study subjects given a saturated fat challenge (i.e. test meal high in saturated fat) following a habitual diet rich in saturated fat experienced a more pronounced postprandial lipemia, compared to subjects given a polyunsaturated fat (PUFA) challenge, following a habitual diet rich in PUFA. An important finding related to the influence of fat type on postprandial lipemia is that chronic supplementation with omega-3 fatty acids has been demonstrated to reduce postprandial lipemia in response to a fat challenge.


Studies have shown that the amount and the nature of carbohydrates in a meal can alter postprandial lipemia. However, in healthy subjects, the physiological range of rise in blood glucose following starchy foods does not induce noticeable alterations in the overall postprandial blood triglyceride response. In contrast, sucrose (table sugar) and fructose (fruit sugar) have consistently been shown to increase the postprandial triglyceridemia.

Dietary fibre

Addition of dietary fibres may modestly reduce the postprandial rise in blood triglyceride levels.


Little information is available so far regarding the influence of the amount or nature of the dietary proteins on postprandial triglyceride response. However, recent studies have shown that postprandial lipemia can be acutely mitigated when proteins are added to the fatty meal.

Effect of meal frequency

In addition to the meal composition, the frequency of meals may also influence postprandial lipemia. It has been found that a minimum of 10 hours is needed for postprandial lipids to return to fasting or baseline levels. As a result, consecutive meals containing fat appear to enhance the lipemia. For example, most meals contain 20-40 g fat, so that when two or three such meals are eaten consecutively, along with snacks eaten between meals, the pattern of consumption might be expected to maintain blood triglyceride levels well above the fasting concentrations for much of the day.

2. Risk of malnutrition

Most of the fad diets overemphasise one particular food type while restricting certain food groups and are therefore nutritionally unbalanced. This increases the risk of inadequate intake of energy and various nutrients such as vitamins and minerals, as well as high-quality protein. Low energy intake can lead to low-performance capacity and tiredness.

3. Other miscellaneous health consequences of fad diets  

Dehydration, decreased bone density, kidney stones, gastrointestinal distress, nausea, kidney stones and risk for eating disorders.


Most of the fad diets overemphasise one particular food type at the expense of other foods or simply eliminate one or more of the essential food groups, with little or no supporting evidence, and are therefore nutritionally unbalanced and unhealthy. These fad diets are not based on any clinical trials and neither the safety nor the long-term efficacy of fad diets is supported in scientific evidence. Furthermore, studies have shown that such fad diets in the long-term are unsustainable, and as highlighted above give rise to several adverse side effects. Given the above, fad diets are better avoided. However, scientific, and clinical communities should not ignore this phenomenon. The public continues to utilize these diets in an attempt to control body weight, oblivious to the potential health damage they may incur through these diets.


Instead of engaging in the next popular fad diet that would last only a few weeks to months (for most people that includes a ketogenic diet), try to embrace change that is sustainable over the long term. A balanced, unprocessed diet, rich in very colourful fruits and vegetables, lean meats, fish, whole grains, nuts, seeds, olive oil, and lots of water seems to have the best evidence for a long, healthier, vibrant life.

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