The July issue of Obesity had this excellent editorial on the state of weight loss. You’ll be surprised by their conclusion. It seems to me that they are supporting a yoga lifestyle of moderation in nutrition and exercise.
In this issue of Obesity, we publish two studies teaching us lessons about the impact of energy expenditure on weight control.
In the first study, Rosenbaum and Leibel reanalyzed most of their data on weight manipulation (gain and loss) with a focus on changes in energy expenditure. They quantified the impact of weight change on the changes in energy expenditure and its implication in body weight regulation. More specifically, they tested whether the decrease in energy expenditure was (a) only proportional to weight loss (mechanical model), (b) decreased after fat stores (and plasma leptin) are depleted to a fixed degree (threshold model), or finally (c) increasingly larger as a proportion of weight loss (spring-loading model). They concluded that none of these three models could singularly account for the decrease in daily energy expenditure following weight loss. Instead, the measured metabolic adaptation was differentially accounted for by a combination of the three models depending on the component of energy expenditure studied (resting, activity related, or food-induced).
The second study reported long-term weight and energy expenditure changes in some of the contestants from the televised weight loss competition “The Biggest Loser.” Fothergill et al. identified a long-lasting, drastic lowering of resting metabolic rate (RMR) as a result of dramatic weight loss, which is consistent with the spring-loading model. However, despite an almost 70% regain of the initial weight loss, this thriftiness (very low RMR) was sustained 6 years after the weight loss. Such results are potentially consistent with the resetting of a biological defense of body weight at an even higher level than before weight loss.
As a result of a front page feature about the “Biggest Loser” study in the New York Times, stories describing the struggles against weight loss relapse went viral. The study triggered online and offline discussions among obesity researchers as well as the general public. The lesson from both studies in this issue is that weight loss triggers a well-documented change in energy expenditure that occurs to counteract the change in weight; however, importantly, the lowered energy expenditure is disproportionate to the magnitude of the weight loss.
Too often, weight loss stories, such as those depicted in “The Biggest Loser,” are portrayed as resounding successes. The “before” stories depict people with out-of-control eating habits and sedentary lifestyles who are affected by severe obesity. At the expense of an enormous effort to beat their biology, they typically first experience an “Aha!” moment when they learn to manage their behaviors to succeed (often for the first time) in losing weight. After a prolonged period of disciplined diet and exercise and strong reinforcement from behavioral coaches, the “after” stories show a dramatically weight-reduced and more confident individual. But the “after-after” depictions uncover a darker outcome, one where weight loss maintenance is difficult, if possible at all, for the resounding majority.
So based on what we now know, what are the lessons learned that can help those people struggling to maintain a healthy weight in our modern “obesogenic environment” conducive to eating more, moving less, and gaining weight at every turn?
- Yes, weight loss, and even dramatic weight loss, is possible. But it is possible only with major expenditure of time, money, and effort. And the kind of weight loss occurring in “Biggest Loser” contestants is almost impossible to maintain long term when the individuals return to their former environments, away from the 24/7 support system of fitness, nutrition, psychological, and medical staff on the TV series and into an environment where there are competing obligations to family, friends, and jobs. The environment that produced the weight loss included high levels of physical activity, extreme attention to portion control, and strong coaching and support. But this heavy-duty regimen is not sustainable. Our environment must accommodate a working life and a social life—something “Biggest Loser” participants experienced on their return to the real world.
- Of the average 58.3 kg lost in 30 weeks of “The Biggest Loser,” 70% was regained over the next 6 years, but the final weight was still 12% lower than before the competition. This is not failure; it is success! Modest weight loss can produce major health benefits, even in individuals with extreme obesity. We are beginning to understand why 5%, 10%, or 15% weight loss has these health benefits.
- The major drivers for weight regain are probably physiological responses to weight loss: (a) the persistence of a very low RMR, 700 kcal/day in absolute value and still 500 kcal/day after adjusting for the lost weight; (b) the lower energy cost of all weight-bearing activities; and (c) the likely persistence of increased orexigenic signals in concert with decreased anorexic hormones.
- From many studies in which RMR was measured before and after weight loss, it is clear that the metabolic adaptation to lower levels is proportional to the amount of weight loss(spring-loading model). So this reduction will be much less with more moderate weight loss.
- For persons with overweight or obesity seeking definitive improvements in their metabolic health, a weight loss of 5%, 10%, or 15% is recommended. With this smaller degree of weight loss, patients are unlikely to experience the extreme calorie handicaps that lead to weight regain that were observed in “Biggest Loser” contestants. Instead, they might see only a small deficit in RMR of 50 to 150 kcal/day.
- Since moderate and realistic weight loss recommendations yield important health benefits, the focus should now shift from striving for dramatic amounts of weight loss toward achieving moderate weight loss with a stronger emphasis on weight loss maintenance. Planning for maintenance should begin during the initial period of loss. To be successful, the new lower body weight is sustained by an environment of healthy behaviors with attention to diet and physical activity as modifiers of the biologic and metabolic adaptations associated with weight loss. It is of the utmost importance to continue lifestyle changes implemented during the weight loss for the long term and to include medications if indicated. Drivers of weight gain (e.g., some medications, sleep deprivation, stress) should be avoided. Also, fore-warned is fore-armed! Patients should weigh frequently and, if small gains are detected, reinitiate the behaviors that produced loss. Finally, bariatric surgical procedures may be appropriate for patients with severe health issues, but they are not without regain issues in many cases.
The only piece of good news from the Fothergill et al. study is that individuals affected by overweight or obesity and struggling to control their body weight can finally be excused for not trying hard enough. Society and health professionals, too, can stop blaming the victims. 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, an emerging frontier in obesity research is weight loss maintenance. We need to better understand the biology behind weight regain if we are to improve treatment. Until we do, we need to be more accepting of variation in body size and focus our efforts on improving the health of our patients who are affected by comorbidity related to excess body fat.