Both moderate and dramatic weight loss lower metabolic rate; Less weight loss is still beneficial to health
In a special mini-series in the journal, leading obesity experts weigh in on the two papers through two additional commentaries and an editorial, all of which explain the phenomenon of metabolic adaptation, or the process where weight loss is accompanied by a decline in energy (caloric) expenditure as weight is lost. These studies were conducted on different populations, but reached the same conclusion: weight regain results from complex biological forces. The common accusation that individuals who don’t keep the weight off just lack willpower is incorrect.
“Obesity is a serious disease that cannot be ‘cured’ with weight loss,” says Donna Ryan, MD, FTOS, Associate Editor in Chief of Obesity and spokesperson for The Obesity Society. “Research is showing that once people lose weight and their metabolism slows, they experience an increase in appetite and a decrease in energy expenditure. These studies demonstrate that keeping the weight off long term requires constant vigilance and lifestyle changes to combat the biologic factors that are fighting to regain the weight.”
In the second paper released today, researchers Michael Rosenbaum, MD, and Rudolph L. Leibel, MD, examined 17 individuals with obesity first at their usual weight, again during maintenance of a 10% reduced weight, and a final time during maintenance of a 20% reduced weight. Their goal was to determine whether the reduction in energy expenditure was directly proportional to the amount of weight lost, if it was proportional up to a certain point, or if it was increasingly – or even exponentially – proportional. They found that all three models were effective.
While these authors found that energy expenditure is explained by a combination of the three models, Fothergill et al’s research on The Biggest Loser contestants seems to fall in line with the proportional model, where the more weight is lost the more the energy expenditure will decrease.
“This study reinforces the complexities of obesity, illustrating that dramatic weight loss, such as that experienced by contestants from The Biggest Loser, may not be the best approach for keeping weight off long term,” continued Dr. Ryan. “Efforts to maintain weight loss should focus on establishing sustainable diet and physical activity routines. While they may not lead to the dramatic weight loss experienced by contestant on The Biggest Loser, they can improve overall health and well-being.”
A position statement on the topic issued today by The Obesity Society and supported by the Academy of Nutrition and Dietetics, the Obesity Action Coalition and the Obesity Medicine Association reinforces the message:
“Many people are successful at losing weight and sustaining that loss at levels that may be associated with significant health benefits, even if they do not conform to a societal cosmetic ideal… Numerous studies have demonstrated that people with obesity can lose 5 – 10% of their initial weight and many of them successfully maintain this new, lower body weight. In addition, reductions of this size are associated with improvements in hypertension, sleep apnea, mood, physical mobility and the development of Type 2 Diabetes.”
Study author Dr. Rosenbaum notes that only approximately 15% of individuals are able to lose more than 10% of their weight non-surgically and sustain the weight loss. The position statement reinforces this idea that “approximately 70% of individuals are capable of weight-reduction of at least 5%, and more than half of these individuals are able to sustain weight loss of >5% at the 8-year mark.”
“These two studies show that keeping weight off can be extremely difficult and gets even harder as more weight is lost. It’s important to remember that moderate weight loss can be beneficial for health and likely won’t come with such a forceful fight by the body to regain the weight,” says The Obesity Society President Penny Gordon-Larsen, PhD, FTOS who led the development of the position statement.A front-page article in The New York Times in May spotlighted a National Institutes of Health study in Obesity that studied 14 former contestants of the reality TV show The Biggest Loser who regained an average of 90 pounds – nearly 70% of what they had lost – six years after the show because of complex factors that affected their metabolism and caused their bodies to regain the weight. Researchers explained that a lowered resting metabolic rate (RMR) was partly to blame. RMR is the rate at which calories are burned at rest, which contributes to total daily energy expenditure (TDEE). This study, which was discussed widely on the Internet following The New York Times story, is now published in the August print edition of Obesity, the scientific journal of The Obesity Society, along with a second, new paper also examining metabolic rates after weight loss.