NPR reports on a recent study in the New England Journal of Medicine, which looked at weight-loss stats of 50 overweight and obese adults, who were put on a restricted diet of just 550 calories a day for 10 weeks. Not surprisingly, they lost a ton of weight, but along the way researchers measured hormone levels of the dieters, including insulin, which regulates sugar absorption; leptin, known to suppress appetite; and ghrelin, which stimulates hunger.
What they found was a bit sobering. Despite the fact that the dieters had lost 14 percent of their body weight in 10 weeks—an average of 30 pounds—their hormone levels continued to surge, causing them to feel more hungry (and deprived) than their bodies actually were.
You can imagine what happened then: If you can’t ignore those hormone-induced urges, you end up putting the weight back on. That’s exactly what happened to the study subjects—they averaged just 8 percent body-weight loss (compared to their starting weights) 15 months after the study began. Sigh.
All that to say, losing weight—and keeping it off—isn’t entirely a mind-over-matter game for most people; your chemical makeup plays a role, and willpower alone can’t carry you. But let’s focus on the good news: Since researchers now have pinpointed an underlying cause, perhaps they’ll be able to figure out how to beat it.