You're listening to TED Talks Daily, where we bring you new ideas to spark your curiosity every day.

I'm your host, Elise Hugh. Obesity is not a lack of willpower. And there is tons of medical research to back this. In her 2024 talk,

obesity physician Catherine Saunders shares the science behind weight, why medications aren't a

quick fix, and what it will take to liberate people from the stigma around obesity.

I'm going to tell you something that's going to surprise you.

It might be upsetting.

And for some of you, it might explain a lot.

And maybe I can convince you that it's liberating.

Your body is evolutionarily conditioned to gain weight, which means that your body is also

evolutionarily conditioned not to lose weight, and definitely not to keep weight off.

According to one explanation called the thrifty gene hypothesis, when we were hunter-gatherers,

our bodies' powerful anti-starvation responses helped us survive.

We had defined our food, and sometimes we couldn't, so our bodies stored calories to keep us alive.

The better we stored calories, the better our chance of survival.

So what changed?

Nowadays, if we can afford food, there's plenty of it everywhere.

We don't have to hunt.

Even the gathering is easy.

We can order food to be delivered directly to our sofa.

And portions are huge compared to even 20 years ago. And a lot of food is tasty, but not so great for us.

We're living in what obesity doctors like me call an obesitygenic environment, limited need

for any kind of physical activity, and easy access to inexpensive, calorie-rich, nutrient-poor

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