Why Diets Always Fail: Harvard Professor Exposes Food Myths | Daniel Lieberman (E439)

Daniel Lieberman (0:03)

Every serving of meat increases your risk of dying in a given year by, I think, 13 percent.

SPEAKER_2 (0:09)

What?

Daniel Lieberman (0:10)

There's no such thing as an optimal diet. There's no magic bullet diet. There's no diet that solves every problem. When you diet, which is to basically eat less fewer calories than you're spending, what happens? We get hungry. Food companies are making a fortune. They add all these additives. So you combine all these products, you have foods that we love, that we crave, and the manufacturers know exactly what they're doing. We're victims, right? I mean, there's so much prepared food and it's so cheap. All you need to know is how to press a button. I think the best diets aren't actually diets.

SPEAKER_2 (0:37)

Let's find out. Daniel, welcome back to High Performance.

Daniel Lieberman (0:45)

Thank you. I'm delighted to be here.

SPEAKER_2 (0:46)

So how would you answer that first question? What if the problem isn't that we don't know enough about diets, but we've misunderstood what humans were actually designed to eat?

Daniel Lieberman (0:54)

Well, I think you hit the nail on the head. I mean, we evolved to get our food, right? I mean, if you're a hunter-gatherer or a farmer, you spend your life working to get your food and to grow your food, and all of a sudden we're in this really weird environment where you walk into a supermarket and there's 30,000, 40,000 different kinds of food, and now we have to choose our food, and we never evolved to do that. And then we get sick from the food that we eat, and now we have to lose weight, and we never evolved to lose weight either. And so we're now asking people to do things that we were never evolved to do, and then we blame them and shame them for making the wrong choice or being confused, as if there's something wrong with them.

So I think an evolutionary perspective can help all of us sort of think better about food and diet and health and how to be kind of nicer to each other.

SPEAKER_2 (1:50)

I say, I really want to dive straight in with a question that is very interesting and you've just said, and I've never heard anyone else say it on our show before, including I think when we spoke last time, maybe you did, but you said we never evolved to diet.

Daniel Lieberman (2:03)

Yeah.

SPEAKER_2 (2:04)

So I feel like, I mean, I'm 47, Damian is 50, Bob, 51

Daniel Lieberman (2:10)

You're youngins.

SPEAKER_2 (2:11)

But we're true, but we are both in a sea of middle-aged men trying to diet the weight off us, feeling like we're failures, wondering like we are struggling. And then you see them and say, well, evolutionarily, we weren't even designed to go on to diet, to lose weight. So we're trying to force our bodies to do something they were never designed to do in the first place.

Daniel Lieberman (2:33)

Correct. When you diet, right, which is to basically eat fewer calories than you're spending. Yeah. What happens? We get hungry, right? And hunger is one of the most fundamental adaptations to prevent us to lose weight.

When you're losing weight, your body mounts a whole suite of responses. These are deep seeded, profound adaptations to prevent us from losing weight. So when your fat cells, for example, produce a hormone called leptin, and when you decrease the amount of fat in your body, your leptin levels drop, your hypothalamus in your brain says, Uh-oh, you're losing fat, and it makes you hungry. When your stomach is empty, your stomach produces a hormone called leptin that makes you hungry. And your intestine doesn't have food. It produces neurotransmitters that send signals to your brain to tell you to eat.

SPEAKER_2 (3:24)

No wonder we're failing.

Daniel Lieberman (3:25)

So no wonder, because we never evolved to do this, because we lived in environments for millions of years where people struggled to get enough food, and body fat plays an incredibly important role in our evolutionary biology. Humans are unusually fat creatures, so we evolved to have a lot of fat and to store a lot of fat, but we never evolved to have the abundance that we have today. And so what happens is that we have this kind of mismatch, right? We end up, you know, we walk into the supermarket, we make the wrong choices, or we just, you know, or whatever, and then we get blamed for them and shamed for them. And then when we try to lose the weight, which is really hard to do, we then were made to feel that something's wrong with us and we're inadequate. It's really, truly, and it's depressingly hard to lose weight. And so I think we need to be compassionate, and we need to help people understand that it's not their fault and give them the information that they need to help them, A, prevent weight gain in the first place, help them understand what's going on with their bodies, and also help them overcome some of these adaptations so that they can do a better job, which is never going to be easy, and we should stop lying to each other.