It’s no secret that many people have a lot of trouble losing weight and keeping it off. But it’s less well known that there’s a concrete, biological reason for this, as Harvard Health Blog explains:

As we lose weight, the body adapts to resist it by lowering the resting metabolic rate — that’s the amount of energy spent while at rest, when the “engine” of the body is idling. Lowering the resting metabolic rate is a good thing if food is scarce and weight loss is occurring due to starvation. In that situation, it’s good that the body slows down to conserve energy and limit further weight loss.

But this evolutionary adaptation works against you if you are overweight or obese, and excess weight is a bigger threat to your health than starvation.

If you watched The Biggest Loser on NBC, you may have heard about this. Researchers looked at the participants and found that many gained weight again after being on the show, because their now-lower metabolic rate was working against them.

For now, medical science doesn’t have a good solution to this problem — the best advice is still simply to eat reasonable portions of nutrient-rich whole foods, more of which should be plant-based than animal-based, and to get regular exercise. If you’re doing that and still not losing much, take heart and know that you’re normal and not alone.

Photo credit: Pete Thomas.