Estimates vary, but it’s believed that more than 80% of people who lose a substantial amount of weight regain it within five years.
But 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,” [said Harvard University] paleoanthropologist Daniel Lieberman.
“We have these big brains, which cost a huge amount of energy. … It’s 20% of our metabolism,” he said. “And a baby, when it’s born, half of its energy is paying for its brain. It needs a lot of fat. So … human babies are born very 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.
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And as for that mismatch between our Stone Age bodies and our modern, obesogenic environment, Lieberman said we have to “figure out how to engineer our worlds to help us make the choices that we would like to make.”
