Battle at the scale: How your body fights to regain lost weight

Losing weight is hard. But as anyone who has dropped a few pants sizes can tell you, keeping it off can be every bit as challenging.
It turns out, though, that it likely takes more than just staying committed to a maintenance diet once you reach your goals. Scientists believe your body might actually be fighting to get back to where it was previously in a phenomenon called the ‘set point’ theory.
The idea is that, for some reason, your body has an idea of what weight it wants you to be, said Oklahoma Medical Research Foundation President Stephen Prescott, M.D. So whether you’ve lost 40 pounds or gained 15, your hormones will adjust in an effort to get you back to a particular point.
“A person’s weight may not always go all the way back to the original weight, but there appears to be some kind of intrinsic desire on the body’s part to get back to a certain weight and stay there,” said Prescott. “It’s not been proven scientifically, but there is increasing evidence to support it.”
The set-point theory isn’t new, but it has been re-popularized because of a recent study by scientists at the National Institute of Diabetes and Digestive and Kidney Diseases, who tracked the progress of contestants from the reality television show “The Biggest Loser.” For six years, they followed contestants after they shed massive amounts of weight for the popular competition.
The researchers’ discoveries gave the set-point theory a lot of ammunition, as the former contestants packed the pounds back on regardless of how strictly they adhered to their diets. Some even gained to a point higher than their original weight.
“It was a really dramatic, attention-grabbing example of the theory as it had previously been described,” said Prescott. “It also shows that there are mysteries we don’t quite fully understand, and you can’t just blame people for getting fat again. Some may not follow their diets as closely as they should, but it appears likely that people also end up fighting their own biology.”
Prescott said the study’s findings point to resting metabolism, or basal metabolic rate, which determines how many calories your body burns at rest.
Our bodies burn energy just keeping us alive. Prescott said somewhere around 70 percent of the calories you use each day are going to get burned no matter what, even if you’re just sitting on the couch or at your desk.
Your age, muscle mass, fitness level and height all contribute to how many calories your body burns. But the findings presented a paradox: The people who gained the weight back appear to have lower metabolic rates than expected based on these factors.
“It’s thought that this could be a result of a complex interplay between hormones that regulate how our bodies burn energy,” said Prescott. “These people were not burning as many calories as you would think based on their height, weight or age. They were gaining weight even on what would be considered a maintenance diet.”
In other words, if you should be burning around 2,000 calories on a maintenance diet based on your personal combination of factors but you have recently lost 20-30 pounds, your actual metabolic rate might have dropped to somewhere around 1,700 or so.
So if your body is determined to gain the weight back even after all your hard work to lose it, does this mean it’s time to throw in the towel and raid the freezer for that pint of rocky road?
“That’s a little too dramatic,” said Prescott. “There may be a tendency to do that, but I think there is hope that there are things you can do to alter or reset your set point.”
To influence this process in your favor, the best solution may rely on an old standby—the gym.
“An exercise regimen often leads to more success in maintaining a new, lower weight,” said Prescott. “Maintaining your new weight may tough, but increased understanding can help you start to rebuild your behavior and habits around a new number for better long-term outcomes.”