“Under normal conditions, humans absorb only about 80% of the nutrients from the food they eat,” says A. Roberto Frisancho, Ph.D., a weight-loss researcher at the University of Michigan. But, he says, when the body is deprived of nourishment, it becomes a super-efficient machine, pulling what nutrients it can from whatever food is consumed. Start eating again normally and your body may not catch up; instead it will continue to store food as fat.
Both men and women are prone to an all-or-nothing approach to weight loss (for example, after a binge, figuring, “Well, I blew it. I might as well go all out!”). But Sass says she sees more women take extreme measures to get back on track, with tactics such as juice cleanses, skipping meals or extreme dieting — not the most sustainable methods. “Most but not all men tend to just try to get back on track with the original plan, or build in a little more exercise,” she says. That is, they take a more balanced approach to getting back on track, just trying to regroup and get back on the diet, or build in a little more exercise.