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Could exercise be the secret to keeping weight off long term? This is what the headlines would have us believe.
"Exercise Keeps Off the Weight" –The New York Times
“The Biggest Loser: Physical Exertion is Key to Keeping Weight Off”-MedScape
“New Study of ‘Biggest Loser’ Contestants Shows Exercise is Crucial for Maintaining Weight Loss”- Yahoo
If you are one of the 91% of women or 43% of men who feel dissatisfied with your body, you have probably read these headlines with great interest. For the overwhelming majority of people, long-term weight loss is elusive. We desperately search for the magic formula to shrink ourselves and blame ourselves each time the plan fails. Could the answer really be as simple as just hitting the gym?
Spoiler alert: it’s not.
The news headlines touting exercise as a weight loss panacea were generated by a research study by Kerns et al. (2017) published in Obesity. Dr. Jennifer Kerns is a former contestant on “The Biggest Loser” who has maintained a 120 pound weight loss, is an obesity medicine physician, and was a medical consultant to "The Biggest Loser" television show.
Dr. Kerns and her research team examined 14 participants on “The Biggest Loser” show before, during, and 6 years after the weight loss competition. The methodology of the study was impressive in terms of the sophisticated techniques used to assess energy intake and expenditure (for an explanation of calculations and procedure, please consult the original research article). Researchers divided participants into 2 groups based on how much weight they were able to keep off over the 6 year time period; those who maintained greater than 13% of weight lost (the median of the group), were considered a “maintainer,” while those that didn’t were considered a “regainer.” On average, the “maintainers” weighed 25% less than when they started the competition while the “regainers” weighed 1% more than when they started.
Results of the study indicate that an increase in energy expenditure (physical activity) was related to long-term weight loss maintenance but a decrease in energy intake (consuming fewer calories) was not. So far, this is all consistent with the headlines, right? Well, here is what most of the news stories left out.
On average, participants in the “maintainer” group were exerting 12.2 kcal/kg/day while the “regainers” were exerting 8.0 kcal/kg/day. The authors estimated that 11 kcal/kg/day (midway between the expenditure of the “maintainer” and “regainer” groups) is the amount of exercise needed to maintain weight loss; this equates to 80 minutes of moderate or 35 minutes of vigorous exercise every single day. The participants who regained the weight were exerting 8 kcal/kg/day but that amount of activity was not enough to maintain the weight loss. These estimates are consistent with prior studies examining the overall physical activity requirements for long-term weight-loss maintenance so the authors don’t just think this applies to “The Biggest Loser.”
It is important to note that this study only measured total energy expenditure each day, it did not assess what types of activities the participants were engaging in or if they were intentionally exercising versus being active as part of their jobs or daily routines. The estimates for amounts of exercise per day assume that the person is completely inactive for the rest of the day (ie. sitting or sleeping the other 23 hours of the day)--which is obviously not the case for most people. Therefore, the amount of intentional exercise may have varied within the groups based on what other activities participants were engaging in throughout the day. The study was also limited by a very small sample-size (14 participants).
So, what is the real headline of this story? Significant long-term weight loss remains elusive. All but one participant in the study regained weight; that one participant who maintained all of the weight loss long-term and had a BMI in the "normal" range was burning 17 kcal/kg/day. Even the group of participants who were physically active for nearly 1½ hours every day, still regained on average 75% of the weight initially lost. Remember, the threshold for successful weight loss in this study was maintaining 13% of the weight initially lost. Participants who were active for less than 80 minutes per day gained back more than 87% of the weight initially lost; on average, the "regainer" group ended up weighing slightly more than when they started the program. Our body fights to maintain a certain set-point weight and the more you lose, the more your body tries to compensate. Our bodies were designed for survival. That’s a good thing.
This study underscores the need for a perspective shift. We are so narrowly focused on weight loss that we ironically encourage unhealthy behaviors in a quest to reach a “healthy” BMI by any means necessary. As I wrote about in previous posts, eating disorders often go undiagnosed—or worse yet encouraged—in people at higher weights. The New York Times wrote in 2016 about a few of "The Biggest Loser" contestants who participated in this study and described worrisome behaviors including restricting food intake, binge-eating, and hitting the gym to exercise multiple times per day.
There is a growing body of research showing that physical activity has health benefits completely independent of weight loss and we don’t need to spend hours each day on the Stairmaster to get these health benefits. Doctors believe that just 30 minutes of moderate exercise is enough to improve your health. Try to find a way of moving your body that is fun and pleasurable. When we shift away from viewing exercise through the punishing weight-loss lens, we can start to find joy in nourishing our body through activities we enjoy.
Dr. Alexis Conason is a clinical psychologist specializing in the treatment of psychological issues related to bariatric surgery, overeating disorders, body image dissatisfaction, and sexual issues. She is the founder of The Anti-Diet Plan, a mindfulness based program to help you stop dieting and start eating in attunement with your body. Sign up for her free The Anti-Diet Plan 30-day starter course today. Follow her on Twitter and like her on Facebook.
References
Kerns JC, Guo J, Fothergill E, et al. Increased Physical Activity Associated with Less Weight Regain Six Years After “The Biggest Loser” Competition. Obesity, 2017; 25, 1838-1843.
