Why losing weight is hard

If you think it’s hard to lose weight and keep it off, you are not alone — and you are also 100% correct. Long-term weight loss is really difficult to achieve, studies have found.

Failure to shed pounds is often not about lacking the willpower to make important lifestyle changes, such as eating healthier, reducing calories and increasing physical activity. The dirty little secret is that our bodies are programmed by evolution to hold on to fat.

“We evolved not to lose weight intentionally,” paleoanthropologist Daniel Lieberman told CNN. Lieberman, a professor and chair of the department of human evolutionary biology at Harvard University, studies why the human body looks and functions the way it does.

“We have these big brains, which cost a huge amount of energy. … It’s 20% of our metabolism,” he said. “A baby, when it’s born, half of its energy is paying for its brain. It needs a lot of fat. Babies are born fat because they have to have that energy to make sure that they can keep their brain going.”

Lieberman said fat is storable energy. It helped early humans stay alive, powered their bodies to find food, kept their brains working and made them healthy enough to reproduce. “It’s like money in the bank account. So individuals who have appropriate levels of fat did better in our evolutionary history,” he said.

Humans never evolved to lose weight deliberately. While our bodies haven’t really evolved from those earlier times, our environment has — and that is, what Lieberman called, a big mismatch. Nowadays, we don’t have to run from wild animals, travel long distances on foot, or hunt and gather our next meal. As a result, many people now live with weight issues and obesity, and all of the “mismatch diseases” that stem from that.

“Mismatch diseases are defined as conditions or diseases that are more common or more severe when we live in environments for which we’re poorly or inadequately adapted,” Lieberman said, referring to our modern-day “obesogenic environment” that often contributes to weight gain.

“Losing weight requires dieting, requires tricking your body and overcoming those adaptations — which your body’s going to fight you every inch of the way.