“Starvation mode” is the theory that when you cut calories too low, your body thinks that it’s starving and responds by hanging onto any calories it gets instead of burning them. The result: You gain pounds, rather than lose 'em. But is this line of thinking legit—or just a way to keep people from taking drastic measures to lose weight?
Turns out it's a real thing, says Holly F. Lofton, M.D., director of the medical weight management program at the NYU Langone Medical Center.
Starvation mode is an actual biological process," says Lofton. "It occurs when we restrict calories and when bodyweight declines.” Back in the day, when food was scarce, it was a way for our bodies to ensure survival. But in today's diet-obsessed world, it works against anyone trying to lose weight.
Yes, anyone trying to lose weight. Even a totally healthy eating plan will result in some degree of metabolic adaptation or adaptive thermogenesis (two scientific terms for starvation mode). In fact, a comprehensive review published in the International Journal of Obesity explains that losing just 10 percent of your body weight results in a 20 to 25 percent dip in your daily caloric burn. Argh.
Metabolic adaptation is a normal process—it takes place when the body uses a blend of hormones, neurotransmitters, proteins, and other chemical messengers to regulate how many calories you burn doing things like breathing, walking, talking, and sweating it out in the gym each day, Lofton says. But when you start eating fewer calories or losing weight, the brain’s hypothalamus and pituitary gland work with other endocrine glands throughout the body to retain calories so you still have enough energy to function properly.
The big issue occurs when your caloric intake is way too low, says Lofton.