Weight Loss Really is Harder for Some
Anyone who has ever tried—and failed—to lose weight has probably had the thought that weight loss is harder for them than for other people. It feels unfair. But it also helps you feel a little better about yourself. “It’s not my fault,” you may have thought.
Now, new research by the National Institutes of Health shows that people with certain physiologies really do lose weight faster—or slower—than others on the same reduced-calorie diet. After conducting a careful, controlled clinical trial with a dozen obese men and women, it became apparent that following an initial day of fasting, some subjects’ metabolisms slowed more dramatically than others’.
Those individuals—whose bodies responded to fasting more dramatically—experienced less weight loss than other subjects during the subsequent period of dieting. Their physiology was dubbed “thrifty”. In response to a day without food, their bodies turned down the metabolic furnace to conserve energy. Other subjects, who continued to burn calories at more or less normal rates, were dubbed “spendthrifts”. Their bodies continued to expend stored calories like there was no tomorrow. These individuals lost weight more rapidly during subsequent weeks of dieting.
For six weeks after the initial day of fasting, the men and women lived as in-patients at a weight loss clinic, where every calorie consumed or expended could be accounted for. "When people who are obese decrease the amount of food they eat, metabolic responses vary greatly, with a 'thrifty' metabolism possibly contributing to less weight lost," said study author Susanne Votruba, Ph.D. "While behavioral factors such as adherence to diet affect weight loss to an extent, our study suggests we should consider a larger picture that includes individual physiology—and that weight loss is one situation where being thrifty doesn't pay.”
Scientists still don’t know if these metabolic differences are inherent, or if they are acquired over time. That’s a question that will need to be addressed by further research. But, for now, it’s possible to say, with some certainty, that some obese people really do have a harder time losing weight than others. But that doesn’t mean they should give up. “…Biology is not destiny. Balanced diet and regular physical activity over a long period can be very effective for weight loss,” said Martin Reinhardt, M.D., lead author.
Martin Reinhardt, Marie S. Thearle, Mostafa Ibrahim, Maximilian G. Hohenadel, Clifton Bogardus, Jonathan Krakoff, and Susanne B. Votruba. A Human Thrifty Phenotype Associated With Less Weight Loss During Caloric Restriction. Diabetes, May 2015 DOI: 10.2337/db14-1881