Biggest Losers are not Best Losers

Recent media coverage of a new study of contestants on NBC’s reality television show The Biggest Loser, published in the journal Obesity, raises serious concerns about drawing conclusions from a single study of 14 individuals, no matter how dramatic the results may be.

The study tracked the lives of contestants before, during and after appearing on the show, as well as the unfortunate individuals who were willing to be re-measured six years later. The study discovered that those contestants experienced a considerable drop in their metabolic rate, which the study’s authors speculated could have contributed to regaining a substantial percentage of their weight. On average, those participants gained back more than two-thirds of the pounds they lost on the program’s extreme diet and exercise regimen.

Not so fast

The coverage of this story is important because it shows us just how harmful it can be to lose massive amounts of weight unnaturally quickly with extreme regimens. (7 hours of exercise a day, anyone?) But the study does not cover, and therefore says nothing about, how metabolism responds to reasonable weight loss that is achieved by reasonable means.

Better weight loss studies

In contrast to this TV contestant study, my lab — the Energy Metabolism Lab at Tufts USDA Nutrition Center — has published two more expansive studies that show almost no negative effect of weight loss on metabolism, beyond that we would expect to result from weight loss alone. In one of our studies[1], 145 participants lost 11% of their body weight and kept it off for two years (the length of the study). They also experienced a drop in metabolic rate of just 5%, and a reduction in total calorie requirements of just 7%.

The relationship between reducing daily caloric intake and a commensurate slowing of the metabolic rate was also studied at Tufts in 30 patients undergoing gastric bypass[2], and their average weight loss of 38% was credited with a decrease in their metabolic rate of 26%, while their total calorie requirements contracted just 24%. These studies show a healthy parallel decrease in weight, metabolism and calorie requirements. They do not show unnatural or harmful drops in metabolism.

Your metabolism doesn’t have to slow

The concept of extreme metabolic adaptation to weight loss (troublesome metabolism slowing) has been blown out of proportion by media coverage. But even this Biggest Loser study doesn’t really support this idea, because the the study used different machines to measure metabolic rate at different times (which can make a big difference). The total calorie requirements of the participants, measured by a different method at 6 years, were decreased by just 10% when their weight was 12% lower than before the program — again suggesting no measurable decrease in total calorie needs beyond those due to becoming smaller.

Quite in contrast to the implications of the media coverage of the TV contestant study, scientifically rigorous studies conducted on people losing weight by less extreme methods indicates that calorie requirements do seem to decrease with weight lost, but the decrease is approximately in proportion to pounds lost. This is a much different, and more positive, message than the one circulating in the media recently; and, rather than instilling the sense of futility that characterizes the experiences of the TV contestants, shows that healthy weight loss can lead to healthy prevention of weight regain when we continue the effective habits that made weight loss possible in the first place.

Ignore the hype

It is not appropriate for the media to extrapolate broad conclusions from a small self-selected group of people undergoing bizarre and unsustainable regimens that are entertaining as in a reality show but are not sustainable. My recommendation is recognize the dramatic weight loss experienced on the TV show is an aberration that should not be confused with the experiences of those who embark on a moderate, healthy well-designed regimen to lose weight and to keep it off.

Since calorie requirements do decrease once your body is smaller, preventing weight regain requires permanent changes to calorie intake (as well as reasonable amounts of exercise — not what the contestants endured). Consuming 10% or 20% fewer calories isn’t something that happens automatically, but it doesn’t need to be a life sentence of deprivation, because many of the good new habits learned during reasonable weight loss can be maintained to prevent weight regain.

The Biggest Loser is certainly entertaining, but the most important lesson we can draw from this study is: don’t try and lose weight the Biggest Loser way!

Warmly,

Susan Roberts PhD

Susan B. Roberts, PhD is Director of the Energy Metabolism Laboratory at the USDA Human Nutrition Research Center at Tufts University, and author of The “I” Diet (Workman Publishing 2010).
[1] http://www.ncbi.nlm.nih.gov/pubmed/26187233.
[2] http://www.ncbi.nlm.nih.gov/pubmed/12816767.