The evolutionary science behind why you can’t lose weight and how to avoid 5 modern food mistakes | Prof Daniel Lieberman

**Unknown - Host from ZOE Science & Nutrition** (0:00)
Welcome to ZOE Science & Nutrition, where world-leading scientists explain how their research can improve your health.
It's 200,000 years BC. A dry wind sweeps across the ancient African savanna, as dawn bleeds red in the horizon. In the half-light, a small band of humans move silently, bare feet pressing into dust as their eyes scan for movement. A child clutches a digging stick. A hunter studies tracks in the earth. Hunger is no stranger to these people. It's an ever-present specter. For more than 99 percent of our history, food was inseparable from effort, uncertainty, and season. But in an evolutionary blink of an eye, our food landscape has utterly changed. We are now rarely more than an arm's length away from food. This sounds like something to celebrate, and yet chronic disease and weight gain is rampant. Is this what happens when a body designed for scarcity collides with the world of abundance?
Today, I'm joined by Professor Daniel Lieberman, one of the world's leading paleoanthropologists, and a professor at Harvard who's published hundreds of papers on evolution. In his latest book, Fed Up, he explains how nothing in biology makes sense unless you view it through the lens of evolution, and that includes diet. In this episode, Daniel takes us on a journey through human evolution and how it relates to nutrition and weight gain. He explains how our evolutionary history can help us understand which diets will really work, why humans have more body fat than hippopotamuses, and he lays out the fundamental building blocks required to follow a healthy, science-backed diet.
Does a healthy human have a higher percentage of body fat than a hippopotamus?

**Daniel Lieberman** (2:01)
Yes.

**Unknown - Host from ZOE Science & Nutrition** (2:02)
Is there a single optimal diet for humans?

**Daniel Lieberman** (2:05)
Absolutely not.

**Unknown - Host from ZOE Science & Nutrition** (2:07)
You're an anthropologist. Does the Paleo diet reflect what people ate in the Paleolithic?

**Daniel Lieberman** (2:13)
No.

**Unknown - Host from ZOE Science & Nutrition** (2:15)
Did many of our ancestors have tapeworms in their guts?
Probably. Finally, what's the biggest myth that you regularly hear about weight loss?

**Daniel Lieberman** (2:26)
That it's easy to lose weight.
There are all these diets out there which say, just do this and you'll lose weight. It doesn't work that way.

**Unknown - Host from ZOE Science & Nutrition** (2:34)
You were on this podcast a couple of years ago, discovering what you discovered about exercise from actually living among tribes who still live in these pre-industrial conditions, which I remember that was absolutely fascinating. If you haven't heard that podcast, I strongly recommend it. But I'm really delighted to have you back because since then, you've actually been working on our favorite topic here at ZOE, which is of course, food. The timing is perfect. Your brand new book, Fed Up, is just about to come out.
You're approaching this with exactly that same insight that comes from this question about our evolutionary history. Why do you think that understanding how we have evolved as humans can help us to understand how to eat better?

**Daniel Lieberman** (3:15)
If I can break that down, there are three reasons. The first is that studying evolution helps give us some perspective.
The perspective I start the book with is that when you walk into a supermarket or even a restaurant, and you're confronted with all these different choices, we never evolved to do that. We never evolved to choose our food. For me, that's the starting point. A typical supermarket has 40,000 different kinds of food. How are you supposed to choose that? Our ancestors ate what they either hunted and gathered, or after we invented farming, they ate what they grew. Now, we have this really bizarre situation, where we have to figure out how to decide what to eat, and then we do so surrounded by advertisements, and all kinds of gurus telling us what to eat, and cultural traditions.
If you're like me, you're very confused about that question. That's the first answer. The second is that evolution explains why things are the way they are. There's a very famous expression, nothing in biology makes sense except in the light of evolution. That's because we weren't designed, we weren't engineered, we evolved. If you want to understand why our digestive system works, why we react this way to certain nutrients or other nutrients, those why questions can only be answered with evolution. How questions can be answered with medical science, but why questions require an evolutionary perspective. And then finally, we're adapted for certain kinds of food and poorly adapted for other kinds of food. And it's not simple. You can't just eat like a caveman and cavewomen. There are all kinds of things that we eat today that they didn't eat and things that they didn't eat that we eat. So it's not a one-to-one guide, but understanding our adaptations I think is critical to understanding how food affects us, but also why pretty much everything has trade-offs. Everything has costs and benefits. That's a key lesson of evolution.