Obesity is now recognized as a serious chronic disease; in my post titled Is obesity a disease or a risk factor for other conditions? I had discussed the magnitude of obesity and why obesity is associated with so much ill-health. However, there are no easy solutions to obesity and managing your body weight is challenging at the best of times. In my post titled Weight Loss Maintenance After Weight Loss, I had discussed how over the long term, the vast majority of individuals regain the weight they have lost and that this relapse has a strong physiological basis and is not simply the result of the voluntary resumption of old habits. Some evidence suggests, however, that a high cardiorespiratory fitness (CRF) might mitigate the detrimental effects of excess body weight on cardiometabolic health, termed the ‘fat but fit’ paradox.
Recognition of the ‘fat but fit’ paradox
In my post, Complications of obesity: the mother of all diseases, I had discussed the various health complications associated with obesity. However, accumulating evidence over the years suggests that being physically fit might attenuate some of the deleterious health consequences of obesity independently of some key potential confounders. About 3 decades ago, a study titled ‘Physical Fitness and All-Cause Mortality: A Prospective Study of Healthy Men and Women’ published in the Journal of the American Medical Association in Nov 1989, brought into focus the detrimental role of fitness (cardiorespiratory fitness [CRF]) vis-à-vis fatness on health, specifically all-cause mortality and CVD-related mortality. This longitudinal study followed up 10,224 men and 3120 women for slightly more than 8 years. The study found that better CRF, as measured by a maximal exercise test, was associated with decreased all-cause mortality in both sexes. Based on the maximal treadmill test, participants were stratified into quintiles of fitness categories. Age-adjusted all-cause mortality rates declined across physical fitness quintiles from 64.0 per 10,000 person-years in the least-fit men to 18.6 per 10,000 person-years in the most-fit men (fat but fit). Corresponding values for women were 39.5 per 10,000 person-years to 8.5 per 10,000 person-years. Lower mortality rates in higher fitness categories also were seen for cardiovascular disease and cancer of combined sites. Higher levels of physical fitness appear to delay all-cause mortality primarily due to lowered rates of cardiovascular disease and cancer.
In my post titled What is obesity – is it merely about BMI? I had discussed, how obesity is defined, the composition of the human body, and fat patterning as well as factors affecting total body fat and fat patterning. Obesity is now recognized as a serious chronic disease; in my post titled Is obesity a disease or a risk factor for other conditions? I had discussed the magnitude of obesity and why obesity is associated with so much ill-health. In my post, Complications of obesity: the mother of all diseases, I had discussed the various health complications associated with obesity. However, there are no easy solutions to obesity, and managing your body weight is challenging at the best of times. In my post titled Weight Loss Maintenance After Weight Loss, I had discussed how over the long term, the vast majority of individuals regain the weight they have lost and that this relapse has a strong physiological basis and is not simply the result of the voluntary resumption of old habits. In my last post, Does obesity hit a point of no return? I had discussed the prospects of long-term success in weight loss maintenance. In the backdrop of the difficulties in maintaining weight loss, I had suggested that emphasis should be on measuring metabolic health and NOT weight. Therefore, in this post, I will discuss the concept of metabolically healthy obesity and debate as to whether it is a myth or a reality.
In my post titled What is obesity – is it merely about BMI? I had discussed, how obesity is defined, the composition of the human body, and fat patterning as well as factors affecting total body fat and fat patterning. Obesity is now recognized as a serious chronic disease; in my post titled Is obesity a disease or a risk factor for other conditions? I had discussed the magnitude of obesity and why obesity is associated with so much ill-health. In my post, Complications of obesity: the mother of all diseases, I had discussed the various health complications associated with obesity. However, there are no easy solutions to obesity and managing your body weight is challenging at the best of times. In my post titled Weight Loss Maintenance After Weight Loss, I had discussed how over the long term, the vast majority of individuals regain the weight they have lost and that this relapse has a strong physiological basis and is not simply the result of the voluntary resumption of old habits.
Prospects of long-term weight loss success
Overall, there is a feeling of pessimism regarding long-term weight loss success. This pessimism started with a study titled ‘The results of treatment for obesity: a review of the literature and report of a series’ published in the journal AMA Archives of Internal Medicine in Jan 1959. The study reported the results of routine treatment of 100 consecutive obese persons in the Nutrition Clinic of the New York Hospital. Only 12 of the 100 patients succeeded in losing more than 20 pounds at any time during the 2 years, and only one of these was able to lose more than 40 pounds. Weight loss maintenance was even more difficult. The study found that one year after treatment, only 6 persons maintained a weight loss of at least 20 pounds and only 2 persons succeeded in maintaining this weight loss 2 years after treatment. More recent studies have also concluded that the probability of attaining normal weight or maintaining a weight loss is low.
A study titled ‘Probability of an Obese Person Attaining Normal Body Weight: Cohort Study Using Electronic Health Records’ published in the American Journal of Public Health in Sep 2015 examined the probability of an obese person attaining normal weight. The study drew a sample of individuals aged 20 years and older from the United kingdom’s Clinical Practice Research Datalink from 2004 to 2014 and analysed data for 76,704 obese men and 99,791 obese women. The authors estimated the probability of attaining normal weight or a 5% reduction in body weight.
Analysis of primary care electronic health records of men and women over 9-year. revealed that the probability of obese patients attaining normal weight was very low. During a maximum of 9 years follow-up, 1283 men and 2245 women attained normal body weight. The annual probability of patients with simple obesity (BMI = 30.0 – 34.9 kg/m2) attaining a normal body weight was only one in 124 for women and one in 210 for men. The likelihood of attaining normal weight declined with increasing BMI category, with an annual probability of attaining normal weight increasing to one in 677 for women and one in 1294 men with morbid obesity (BMI = 40.0- 44.9 kg/m2). The annual probability of achieving a 5% reduction in body weight was 1 in 10 for women and one 1in 12 for men with simple obesity. However, the likelihood of attaining a 5% reduction in body weight improved with the increasing BMI category, with 1 in 7 women and 1 in 8 men with morbid obesity attaining a 5% reduction in body weight. Although the probability of patients achieving a 5% reduction in body weight was considerably higher, the majority of these patients went on to regain lost weight, within 2 to 5 years. Thus, the study findings indicate that current non-surgical obesity treatment strategies are failing to achieve sustained weight loss for the majority of obese patients. The study concluded that for patients with a BMI of 30 kg/m2 or greater, maintaining weight loss was rare and the probability of achieving normal weight was extremely low.
In my post titled ‘Weight Loss Maintenance After Weight Loss, referred to above, I have discussed how the body regulates body weight and various factors responsible for weight regain, including physiological adaptations to weight loss and factors favouring weight regain, which are potent enough to undermine the long term effectiveness of lifestyle modifications, particularly in a ubiquitous obesogenic environment, potentially favouring long-term weight regain. The compensatory changes in biological pathways which encourage weight regain following weight loss encompass appetite regulation, energy utilization and storage. These changes affect our complex neuro-hormonal system that regulates energy homeostasis including perturbations in the levels of circulating appetite-related hormones and energy homeostasis, as well as alterations in nutrient metabolism and subjective appetite. Besides, as discussed in my above post, habituation to rewarding neural dopamine signaling develops with the chronic overconsumption of palatable foods, leading to a perceived reward deficit and compensatory increases in consumption. These physiological adaptations would have been advantageous for a lean person in an environment where food was scarce; however, in an environment in which energy-dense food is abundant and lifestyles are largely sedentary, it results in a high rate of relapse after weight loss.
The potential long-term role of these physiological adaptations in weight regain has been validated in various studies; one landmark study titled ‘Persistent Metabolic Adaptation 6 Years After “The Biggest Loser” Competition’ published in the journal Obesity in August 2016, measured long-term changes in resting metabolic rate (RMR) and body composition in participants of “The Biggest Loser” competition (The Biggest Loser is an American competition reality show; it’s a 30-week long competition that features obese or overweight contestants competing to win a cash prize by losing the highest percentage of weight relative to their initial weight). The study followed the participants of ‘The Biggest Loser’ competition for 6 years and measured the resting metabolic rate (RMR), metabolites and hormones, including leptin, before and after the competition, as well as 6 years later. A mean weight loss of 58.3 kg was observed during the competition which resulted in a substantial decrease in RMR of up to 610 +/- 483 kcal/day. These investigators also estimated that this decrease included a metabolic adaptation (also known as adaptive thermogenesis; it refers to fat-free mass [FFM]-independent decreases in energy expenditure) of 275 kcal/day representing a decrease exceeding what would have been predicted by the loss of fat mass and fat-free mass. Six years after the end of the competition this decrease in metabolic adaptation was even more pronounced. The mean metabolic adaptation had increased to 499 kcal/day, which explains why RMR remained 704 kcal/day below the baseline level despite a 41 kg regain in body weight. Similarly, plasma leptin level was drastically reduced at the end of the competition and remained significantly lower than baseline, even at the end of 6 years despite an almost 70% regain of the initial weight-loss. The results of this study are compatible with the previous long-term studies having shown that substantial weight loss induces biological adaptations that promote weight regain. Rather, the results of this study reveal a more darker side of this story, and that is an amplification of the metabolic adaptations over time. Laziness is clearly not a factor in the weight regain seen in contestants of “The Biggest Loser”. In fact, it may be challenging to find a more dedicated group of individuals.
Thus, there is enough scientific evidence to suggest that these biological adaptations which promote weight regain, often persist indefinitely, even when a person re-attains a healthy body weight via behaviorally induced weight-loss. More importantly, as discussed above, it appears that the biological pressure to restore body weight to the highest-sustained lifetime bodyweight gets stronger as weight loss increases. Therefore, it may be apt to suggest that few individuals ever truly recover from obesity; individuals with obesity, who are able to re-retain a healthy body weight via behaviorally induced weight loss still have “obesity in remission” and are biologically very different from individuals of the same age, sex and bodyweight who never had obesity.
Unfortunately, despite obesity research consistently showing that dieters are at the mercy of their own bodies, which muster hormones and an altered metabolic rate to pull them back to their old weights, due to lack of adequate awareness about the biological mechanisms responsible for weight regain, not only the majority of individuals themselves, but the society at large and even the healthcare professionals blame the patients when the lost pounds creep back in. The serious impact of such a blame game has been discussed at length in my posts titledWeight Bias: pervasive yet hidden harm of obesity. In this background, the only piece of good news from the study of the competitors of ‘The Biggest Loser’ competition is that individuals with overweight or obesity and struggling to lose their body weight can finally be ‘excused’ for not trying hard enough. It can be best illustrated in the words of one of the competitors of ‘The Biggest Loser’ competition. Quote “The biggest loser did change my life, but not in a way that most would think. It opened my eyes to the fact that obesity is not simply a food addiction. It is a disability of a malfunctioning metabolic system.” Unquote. Another competitor stated – Quote “That shame that was on my shoulders went off.” Unquote. After all, it is more than evident now that the difficulty in keeping the weight off reflects biology, not a pathological lack of will power.
As discussed in my post Diet Plan for Weight Loss – It’s going to be a journey, this sentiment is exploited to the hilt by the dieting and weight loss industry. Too often, weight loss stories, such as those depicted in “The Biggest Loser” are portrayed as resounding successes. The ‘before’ and ‘after’ stories, wherein the ‘before’ stories depict people who are affected by severe obesity due to unhealthy lifestyles, and ‘after’ stories show a dramatically weight-reduced and more confident individual after a period of disciplined diet and exercise and strong reinforcement from the behavioural coaches. But this picture is incomplete; it is the “after-after” depictions that uncover a darker outcome, one where weight-loss maintenance is difficult, if possible at all, for the resounding majority.
As reiterated above, long term weight loss happens to only the smallest minority of people. If we check back after a few years, there is a good chance that the vast majority of these people will have put the weight back on. The National Weight Control Registry (NWCR), was established in 1994 in the USA to study weight loss and weight maintenance strategies of successful weight loss maintainers. It has been billed as the largest prospective investigation of long-term successful weight loss maintenance. Besides, part of the reason for developing the NWCR was to counter the belief that ‘no one succeeds long-term at weight loss.’
This registry is a self-selected population of individuals who are age 18 or older and have lost at least 30 pounds (13.6 kg) and kept it off for at least one year. According to its website (nwcr.ws), the registry is tracking over 10,000 individuals who have lost a significant amount of weight and kept it off for long periods of time. Research findings from the NWCR have been featured in many national newspapers, magazines and television broadcasts, including USA Today, Oprah Magazine, The Washington Post, and Good Morning America. To define successful long- term weight loss maintenance, Wing and Hill, who established this registry, proposed that individuals who have intentionally lost at least 10% of their body weight and have kept it off at least one year be considered “successful weight-loss maintainers.” Even by this definition, the registry has reported that only 21% of overweight/obese persons may be successes.
However, NWCR has many shortcomings. Firstly, NWCR is an observational study, not a clinical trial, and correlations don’t prove causation. Secondly, because this is not a random sample of those who attempt weight loss, the results have limited generalizability to the entire population of overweight and obese individuals. Thirdly and most importantly is the numbers. In 2016, the population of the US was approximately 323.23 million. According to the NCHS Data Brief, No. 313, Jul 2018 on ‘Attempts To Lose Weight Among Adults in the United States, 2013 – 2016’, in 2013 – 2016, 49.1% of the US adults tried to lose weight in the preceding 12 months. In absolute numbers, this works out to approximately 158.70 million adults. Though figures reported in the literature for permanent weight loss in people who try to lose weight are quite dismal, as highlighted above, however, here a more optimistic figure of 5% reported in scientific literature is being considered. At this rate, approximately 7.93 million American adults should have succeeded in achieving permanent weight loss in 2016 and therefore be eligible for enrolment in the NWCR.
According to the NWCR website, over the last about 26 years (i.e. from 1994 to 2020), about 10,000 people have been enrolled in the registry. Though it’s difficult to assess the number of adults who would have dieted over this corresponding period and succeeded in achieving a permanent weight loss, however, at the rate of 2016, approximately 206 million (7.93 X 26 = to 206.18) American adults might have succeeded in achieving permanent weight loss during this period. However, the population in 1994 was lesser, being approximately 263 million and the number of people who attempted weight loss then, is not known. So, for the purpose of illustration, a very conservative figure, almost half of the 206 million who may have successfully lost weight, i.e. only 100 million, is being considered here. Therefore the NWCR figure of 10,000 is a tiny fraction of all adults who attempted weight loss over this period and apparently succeeded – less than 0.001% even under a best-case scenario. To demonstrate a 5% success rate, the NWCR would have to enrol at least additional 99.99 million successful weight losers. Therefore, the NWCR participants are definitely the exception and not the rule when it comes to intentional weight loss.
However, a positive takeaway from the NWCR is the validation of the strategies of long-term success at weight loss and the fact that the individuals can do it consistently. The key strategies for long-term success at weight loss seen among the NWCR participants fall into three categories: eating habits, self-monitoring, and physical activity. These include:
Eating a diet that is low in calories and fat.
Maintaining a consistent eating pattern; registry members try to eat regularly and avoid situations that encourage overeating.
Self-monitoring weight on a regular basis. Over 75% of registry members weigh themselves more than once per week, and 50% count calories and/or fat grams.
Engaging in high levels of physical activity. The average successful weight loser reported engaging in a level of physical activity that is equivalent to about one hour of moderate-intensity physical activity, such as brisk walking, per day. This is considerably more than the minimum recommendations proposed by the Surgeon General’s report. The time spent on physical activity likely comes at the expense of more sedentary activities. The average registry member tends to watch only 6 to 10 hours of television per week, in stark contrast to the average American adult, who spends an average of 28 hours per week watching TV.
Catching ‘slips’ before they turn into larger regains.
So, does obesity hit a point of no return?
In the light of the above discussion, it is quite evident that not only for people attempting to regain their ‘normal’ body weight but even for vast majority of people attempting to maintain even moderate weight losses in the long term, the answer, unfortunately, seems to be in the affirmative.
So what does this mean for millions of people around the globe attempting to lose weight?
Health experts are afraid that following such a harsh message (failure to maintain weight loss), people will abandon all efforts to exercise and eat a healthy diet, behaviours that are important for health and longevity, even if it does not result in significant weight loss. Nevertheless, the findings on metabolic adaptations should not be interpreted to mean we are doomed to battle our biology or remain fat. Rather it means we need to explore other approaches. Primarily, clinicians should proactively address obesity prevention with overweight individuals, or for that matter, even healthy weight individuals and, for those who already have sustained obesity, clinicians should implement a multifaceted treatment strategy that includes biologically based interventions such as anti-obesity drugs and bariatric surgery (however, bariatric surgery has its complications, life-threatening at times) when appropriate. However, lifestyle modifications continue to be the cornerstone of the management of obesity in even patients with sustained obesity.
Behavioural approaches for the management of obesity combine diet, exercise and cognitive strategies. It is important to emphasise here that healthy lifestyle behaviours still remain healthy even if it doesn’t make you thin. Eating healthy and remaining physically active has several health benefits and reduces the risk of various obesity-related complications, irrespective of whether you lose weight or not. Increasing evidence suggests fitness and diet may affect health independent of weight status, and that obesity and fitness are non-mutually exclusive (i.e. they can occur together). In fact, fitness maybe as relevant a predictor of mortality as diabetes mellitus and other CVD risk factors, and it may be a stronger predictor than BMI, obesity or abdominal obesity. Obese individuals who engage in moderate-intensity physical activity as per WHO guidelines have half the death rates and lower rates of CVD than their unfit normal-weight counterparts. Furthermore physically active overweight or obese individuals may have greater cardiorespiratory fitness (and thus have a better quality of life) than inactive individuals regardless of weight status. Therefore, the emphasis should be on measuring (metabolic) health not weight.
Another important aspect worth reiterating is the importance of setting moderate and realistic weight loss targets. As discussed in my post titled Diet Plan for Weight Loss – It’s going to be a journey, referred to above, under ‘setting weight-loss targets’, I had discussed as to why in the light of the current findings the focus should now shift from striving for dramatic amounts of weight loss towards achieving moderate weight loss with a stronger emphasis on weight loss maintenance. As highlighted there, weight losses of only 5 to 10% of initial body weight are sufficient for clinically meaningful reductions in risk for various obesity-related health complications, even though this level of weight loss might be disappointing to some patients with more ‘aesthetically driven goals’.
It would be prudent to emphasise here that body size and shape vary systematically in modern humans, and did so in earlier humans as well. Differences in body form among humans are likely to result from an interaction between long-term genetic factors, including climatic adaptation, as well as the developmental environment, including diet and disease. Therefore we need to be more accepting of variation in body size and focus our efforts on improving the health of people who are affected by comorbidity related to excess body fat. Besides moderate weight loss has a higher probability of being sustained in the long term. The metabolic adaptations to lower levels are proportional to the amount of weight loss. So this reduction (in metabolic adaptations) will be much less with moderate weight loss, thereby reducing the biological pressures to regain the lost weight.
Importance of early intervention and prevention
Lost in all of the noise about strategies for weight loss and difficulties in maintaining weight loss is the important concept of prevention – of not putting weight on in the first place. It is much easier to prevent obesity from developing then to treat it once it occurs. The focus on prevention should start from early childhood onwards and clinicians should address the importance of proper nutrition and physical activity before the development of obesity.
Specifically, clinicians should be proactive in addressing obesity prevention with patients who are overweight; treatment should focus on preventing these patients from gaining further weight. Several biological adaptations that preserve the highest lifetime body weight do not seem to occur until obesity is sustained and, therefore healthy lifestyle choices might be sufficient for lasting reductions in bodyweight before sustained obesity. However, once obesity is established, bodyweight seems to become biologically stamped in and defended.In other words, the longer a person is overweight, the higher the risk of obesity becoming irreversible.
Investing in the prevention, management and treatment of obesity is a cost-effective action for governments and health services. To underline the significance of early intervention and prevention, the World Obesity Federation selected the theme “Treat obesity now and avoid the consequences later,” for theWorld Obesity Day 2017.
For World Obesity Day 2021, the World Obesity Federation has chosen the theme – “Every Body Needs Everybody”. An animation based on the same is given below.
Before I discuss the main topic of weight loss maintenance, it would help to give you a brief overview of obesity. The world is in the grip of an obesity epidemic. In my post ‘What is obesity – is it merely about BMI?‘ I had defined obesity as “excessive body fat accumulation (not weighing too much), which is associated with clear risks to health.” 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 Complications of Obesity: the mother of all diseases I had discussed how obesity affects almost every aspect of health, from reproductive and respiratory function to memory and mood; it decreases both the lifespan and the quality of life and increases costs of health care, both at the individual as well as at the national level.
However, rather than considering obesity in a conventional way, one aspect that needs serious consideration is that normal weight doesn’t always equal ‘healthy weight’. In my post ‘Normal Weight Obesity – a myth or a reality? I had described individuals who have weight within normal limits according to the BMI but have a high body fat percentage and are predisposed to the same health risks as in ‘obesity’. Another worrying trend is the increasing incidence of Childhood obesity.
Lifestyle modifications encompassing dieting, physical activity and behavioural modifications often lead to weight loss. However, over the long term, the vast majority of individuals regain the weight they have lost. The trajectory of weight change during/after behavioural weight management interventions mostly follow a typical pattern; the obesity interventions typically result in early rapid weight loss followed by a weight plateau and then progressive regain. Thus, the main challenge of obesity treatment is not weight loss, but long-term weight loss maintenance.
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.
Obesity continues to be a major worldwide health problem, despite the efforts of the medical community. Intensive lifestyle interventions can achieve weight loss that is sustained over the long-term. Diet is an important component of any lifestyle intervention programme. The dietary plan that restricts energy and fat is the most common strategy and based on it, several other dietary strategies have been proposed. However, the very-low-carbohydrate, high-fat keto diet differs from these approaches.
In my post Diet Plan for Weight Loss – It’s going to be a journey, I had described various options for the treatment of obesity. As highlighted there, the core principle of any obesity treatment is that it must shift the balance between energy intake and energy expenditure – treating obesity requires creating a state of negative energy balance, thereforea reduction in energy intake is the primary factor that needs to be addressed in a dietary intervention designed to promote weight loss. In the above post, under dietary interventions for the management of obesity, I had briefly discussed the various calorie reduction strategies including reduced-calorie diets, low-calorie diets (LCD), very-low-calorie diets (VLCD) and #keto diets. In the above referred to post, I had discussed reduced-calorie diets in details; in my post, Very-Low-Calorie Diet – All you Need to Know, I had discussed the LCDs and VLCDs. Here, in this post, I shall be discussing the keto diets.
In my post Diet Plan for Weight Loss – It’s going to be a journey, I had described various options for treatment of obesity. As highlighted there, the core principle of any obesity treatment is that it must shift the balance between energy intake and energy expenditure – treating obesity requires creating a state of negative energy balance, thereforea reduction in energy intake is the primary factor that needs to be addressed in a dietary intervention designed to promote weight loss. In the above post, under dietary interventions for the management of obesity, I had discussed various calorie reduction strategies including reduced-calorie diets, low-calorie diets (LCD) and very-low-calorie diets (VLCD). In the above referred to post, I had discussed reduced-calorie diets in details; here, in this post, I shall be discussing the other two diets plans viz. low-calorie diets and very-low-calorie diets. The use of very-low-calorie diets to induce rapid weight loss, in contrast to many other weight loss products in the market, is backed by decades of medical research, and very-low-calorie diets have been in clinical use for almost 40 years.
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.
Worldwide prevalence of obesity has been increasing at a menacing pace. As per WHO data, the incidence of obesity worldwide has tripled since 1975. As discussed in my post ‘Is obesity a disease or a risk factor for other conditions?’ in 2016 more than 1.9 billion adults, 18 years and older, were overweight; of these 650 million were obese. It has assumed epidemic proportions in children too. As discussed in my post ‘Childhood obesity: a serious public health challenge’, as per a study led by Imperial College of London and WHO, in a span of just 40 years, the number of school-age children and adolescents (5-19 years of age) with obesity has risen more than 10-fold from 11 million in 1975 to 124 million in 2016. Unfortunately, the obesity epidemic has been accompanied by a parallel epidemic of weight bias.
In my post ‘Complications of obesity: the mother of all diseases’, I had highlighted that obesity affects almost every aspect of health, from reproductive and respiratory function to memory and mood. Among the various psycho-social complications of obesity, I had discussed weight bias, which negatively affects not only psychological well-being but physical health as well. Although weight bias is pervasive in society and undermines people’s health extensively, awareness about it is very limited. In order to raise awareness about the prevalence, severity and diversity of weight stigma, the World Obesity Federation chose ‘End Weight Stigma’ as the theme for the World Obesity day 2018. To begin with, to help understand the topic better, the term weight bias and other related terms will be explained here briefly.
In my post ‘What is Obesity – is it merely about BMI? I had discussed the definition of obesity, as laid down by the WHO, as “A condition of abnormal or excessive body fat accumulation, to the extent that health may be impaired.” People who are obese are at increased risk for many serious diseases and health conditions, compared to those with a normal or healthy weight. However, in my post “Normal weight obesity – a myth or a reality?” I had discounted a widely prevalent myth amongst the general populace that ‘normal body weight always equals healthy weight’. There I had discussed a subset of individuals, among individuals with normal body weight, who develop and suffer from complications of obesity similar to individuals with a more ‘overt’ obesity.
Obesity affects almost every aspect of health, from reproductive and respiratory function to memory and mood. It decreases both the lifespan and the quality of life and increases costs of health care, both at the individual as well as at the national level. It does this through a variety of pathways; some as straightforward as the mechanical stress of carrying extra weight and some as a result of excessive secretion of certain products by enlarged fat cells and ectopic fat depots. The mechanisms by which obesity gives rise to its various ill-effects on health were discussed in my post “Is obesity a disease or a risk factor for other complications?”
However, the good news is that weight loss can reduce some of the risks associated with obesity. Loss of as little as 5 to 10 per cent of body weight provides substantial health benefits to people, and even if they begin to lose weight later in life.
Childhood obesity has reached epidemic proportions and is today one of the most serious public health challenges of the 21st century. The problem is global; even though, more recently the childhood obesity rates appear to be plateauing in high-income countries, albeit at unacceptably high levels, they continue to soar in low- and middle-income countries. A study led by Imperial College, London and WHO, which analysed weight and height measurements from nearly 130 million people, including 31.5 million children aged 5-19 years of age, was published in ‘The Lancet’, a prestigious medical journal, on the eve of the World Obesity Day on 11th Oct 2017. According to the study, the areas of the world with some of the largest increase in the number of obese children and adolescents were East Asia and the Middle East and North Africa.
The rise in childhood obesity rates has recently accelerated, especially in Asia. According to the study, the world will have more obese children and adolescents than underweight by 2022. Unfortunately, in spite of the rapid rise in child and adolescent obesity rates globally, few countries are taking action against this damaging health issue. To focus world attention on this burning issue, World Obesity federation chose the theme ‘Childhood Obesity’ for the World Obesity day 2017, celebrated on 11th Oct each year.
In 1997 the World Health Organisation (WHO) Expert Consultation on Obesity recognised the importance of abdominal fat mass (referred to as abdominal, central or visceral obesity), which can vary considerably within a narrow range of total body fat and body mass index (BMI). It also highlighted the need for other indicators to complement the measurement of BMI, to identify individuals at increased risk of obesity-related diseases. Two such proxy measures of abdominal obesity, which can complement the measure of BMI are waist size (circumference) and waist-to-hip ratio (WHR).
In my post ‘What is obesity – is it merely about BMI? What is obesity? I had highlighted that over the years, starting from the early 1980s, many research studies had confirmed the notion that rather than the excess body fat per se, regional distribution of body fat at different anatomic sites was much more important in driving the risk of cardiovascular diseases and other health hazards linked to obesity. In the same post I had described ‘abdominal obesity’ (individuals with excess intra-abdominal fat) and a characteristic obesity phenotype – ‘Asian Indian Phenotype or Paradox’ (Asians, particularly people in South-East Asia and China, displaying a greater amount of intra-abdominal fat for a given waist size [circumference] or BMI).
In my post “What is Obesity – is it merely about BMI? What is obesity? I had defined obesity as an abnormal accumulation of fat such that health is impaired. Body Mass Index is the most widely used measure of identifying obesity. However, in my post, I had cautioned that contrary to the general perception, obesity is not about BMI. In this post, I will be discussing what is Body Mass Index, its advantages and limitations. In addition to describing the method for calculation of BMI, for the ease of readers, I will be briefly discussing ‘BMI calculator tool’ and ‘BMI charts’.
What is Body Mass Index
Body Mass Index is a simple index of weight-for-height that is commonly used to assess ‘normalcy’ for body weight. It is defined as the body mass divided by the square of the body height. It is universally expressed in units of kg/m2, resulting from body mass in kilograms and height in meters. If pounds and inches are used as a measure of body mass and height respectively, a conversion factor of 703 is used. The formula for calculation of Body Mass Index is as under:
There is a widely prevalent myth amongst the populace that normal body weight always equals healthy weight and they do not need to worry about practising healthy lifestyle behaviours. However, nothing could be further from the truth. Normal weight obesity is well recognised entity. In my post “What is obesity – is it merely about BMI?” What is obesity? obesity had been defined as “excessive body fat accumulation (not weighing too much), which is associated with clear risks to health.” Surprisingly, even though obesity has been defined as the presence of ‘excess’ fat, there is no consensus on how to define obesity based on body fat content or body fat percentage.
WHO has established Body Mass Index (BMI) as the parameter for identifying overweight and obesity. Because of its simplicity, it has become a popular tool for assessing the prevalence of obesity and overweight at the population level. However, BMI has some serious limitations which will be discussed in detail in a subsequent post. The main limitation of BMI is that it cannot differentiate body fat from lean (fat-free) mass and central (intra-abdominal fat or visceral fat; colloquially known as belly fat) from peripheral fat. As a result, current BMI criteria miss more than half of the individuals with increased body fat percentage, who would otherwise be categorised as ‘obese’ using the WHO criteria of excess body fat, especially in older adults.
In my earlier post “Is obesity a disease or a risk factor for other conditions”? I had highlighted that now obesity is recognised universally as ‘a chronic, relapsing, progressive disease process.’ However, misconceptions still abound about ‘what is obesity’, not only in the public at large but even among the health professionals. Traditionally, when talking about what is obesity, we tend to erroneously confuse how we measure obesity with the definition of obesity. One such popular and well-known measure of obesity, which will be discussed subsequently, is Body Mass Index (BMI). BMIHowever, obesity is not about BMI; at its most basic, the term obesity describes the presence of ‘excess’ fat in the body.
Definition of obesity
In the year 1998, WHO defined obesity as under:
“A condition of abnormal or excessive body fat accumulation, to the extent that health may be impaired.”
In the year 2010, Scottish Intercollegiate Guidelines Network, part of the NHS Quality Improvement Scotland, described obesity as under:
“Obesity is defined as a disease process characterised by excessive body fat accumulation with multiple organ-specific consequences.”