And what is the role of fiber in this equation?

Oh, gosh, fiber does so many things.

I mean, fiber, the more we study fiber, the more we're learning about just how important it is in our diet.

So fiber are carbohydrates that technically we can't digest, like the plant walls, you know, all the things in plants, like grass.

Grass is full of fiber, right? But that fiber does many things in our digestive system.

So one of them is that it, so when food is, once it leaves your stomach, we call that chyme.

C-H-Y-M-E, it's not yet poop, right? Poop is when it finally leaves your body.

And it just feels like we're always jumping into these fantastical ideas around all of these approaches.

How did hunting become not the only, but a very important part of the way that humans got their food back in the days? So why don't we go briefly into that story?

We started eating meat, we eating our ancestors meat.

At least two and a half million years ago, probably a bit older, exactly when the first hunting, first scavenging occurred is controversial.

But by two and a half million years ago to two million years ago, it became a regular thing.

And certainly by two million years ago, early hominins at that time, Homo erectus probably was hunting large, big animals, the kind of ancestors of kudus and wildebeests and things like that.

And of course, that was long before any projectile technology.

The bow and arrow wasn't invented for another two million years, and the atlatl, and the spear thrower, and even spear points were maybe as old as 500,000 years ago.

But is there still something that we can say in general about how the eating habits of humans change with the advent of farming?

... people believe the paleo diet should be?

I mean, God only knows what the hell the paleo diet is.

It's, it's based on, um...

From my understanding, it was based on there's a thing called the Ethnographic Ax- A- Atlas by a guy named Mur- Murdock.

And, uh, I think, um, what they did is they kind of looked at the Ethnographic Ax- A- Atlas, did some statistical manipulations with the diet, with the data there, most of the data aren't really very good, and then came up with some kind of, uh, percentages of what they thought a true paleo diet was.

Um, we actually published a paper in the American Journal of Clinical Nutrition a few years ago, um, where we analyzed all the really high quality diets of hunter-gatherers from the tropics and compared them to the paleo diet.

Turns out none of them [laughs] are like the paleo diet.

But how would you, in a nutshell advise somebody to eat more like a fox with perhaps like explicit principles or pointers?

Describe the Mediterranean diet.

Well, the Mediterranean diet is, is, uh, you know, there's, there's, there's two Mediterranean diets.

There's the, there's the Mediterranean diet with a capital M, capital D that has been defined by, by nutritionists, [laughs] and then there's the Mediterranean diet that people in the Mediterranean sort of actually eat.

And, of course, the latter is extremely variable and, and, um, and hard to characterize very simply.

But, but the, but the Mediterranean diet with capital D, um, is essentially, uh, a diet that's based on whole grains, so, um, often with sourdough, for example, uh, plus legumes.

So you'd have, uh, think about you might have pasta or you might have, uh, bread or something like that or, uh, with, with, uh Chickpeas or lentils or, you know, some kind of legume or bean like that, plus lots of vegetables and fruits, plus moderate amounts of, of dairy, so some cheese.

Um, uh, you pri- prioritize, uh, fish over really fatty meats, but you do eat meat occasionally, just not, not all the time.

So tell us about why or how evolution has made dieting so difficult.

But the general rules of nutrition, of like what the human body needs to function and stay healthy, uh, uh, do they vary that much from person to person?

Not too much, no. Um, what you need, though, isn't necessarily what's best for your long-term health, right? I mean, what...

People can survive on 100% meat diet.

The only food you actually [laughs] need to eat, apart from some vitamins and minerals is meat, is protein, right? Uh, well, you don't, you don't need to get protein from meat.

You can get protein from plants.

But, but protein is the only nutrient you actually have to ingest.

You can, you could technically survive without eating carbohydrates, and you could technically survive without eating, um, without eating fats.

So given all you've said about this, a person listening thinking, "Yeah, well, I, I get that, but w- what do I do?" I mean, in a practical way, what is the information you've just given us, what do I do with it, and how do I move forward?

I mean, the consensus seems to be that for a while at least, meat and fats and limited carbs and leafy greens, they've got enough nutrition to get you by.

Oh, yes.

No, I mean, meat is incredibly nutritious.

You can live for a long time on an all-meat diet.

And ketosis is just when you're burning fat, not carbs, can have benefits.

And we're adapted for that, right? But I just don't know of any evidence that we're adapted to be in ketosis for 24-7, right, all the time.

The evidence really is that it's good to kind of cycle in and out and in and out.

Do you have a simple rule of thumb about fats?

Why do you think it does show up in mice?

Because mice have totally different l- uh, life histories.

So life history is the series of stages that you go through, how you use energy to grow up, reproduce, and, and whatever.

And, and you know, a typical mouse is ready to reproduce after three months, you know, and it has series of babies, et cetera, et cetera.

Mice have totally different metabolisms and different growth trajectories and diff- different d- uh, microbiomes and different, you know, than, than humans.

So, so yes, it is true that, uh, uh, for some species, for some, um, mouse lines, but not all, caloric restriction has been shown to improve their lifespan, but not all of them, by the way.

Um, certainly true for yeast, certainly true for fruit flies, but the evidence for humans is so far mixed.

Hmm.

What is your verdict on this?

[chuckles] Well, again, the calories in, calories out is a-- is another classic example of an oversimplification, right? And again, all these diets, the problem with them is that they're oversimple.

Yes, it's true that we end up balancing calories in versus calories out.

We are, we are subject to the laws of thermodynamics just like every other creature.

But two things.

First is our bodies don't treat all foods the same because we have these things called hormones that allocate energy for-- and change how our bodies digest and, and, and, and move nutrients or-- and energy around our body, which is one of the reasons why carbohydrates have different effects, say, on our fat storage, for example, than, than, say, fats or proteins.

We can get to that later on.

Has the way we sleep changed from the way in which we evolved? And could these sleep patterns have any effect on, like, the patterns in, in the way in which we eat?

They say it's really bad for your knees.

Oh, man, that gets me so mad, right? I mean, I hear this from doctors all the time, right? "Oh, yeah, running is bad for your knees." Now, it is true that knee injuries are the most common running injuries.

Um, um, but arthritis, which is really what they're usually talking about, um, it's absolutely definitively not true that running increases rates of knee, uh, cartilage damage and arthritis.

So, arthritis is caused by cartilage wearing away in a joint, right? And it's- it's a- it's a myth that, uh, c- running actually increases car- cartilage damage.

If you have arthritis, running is excruciating and problematic.

But if you don't have it, running actually, uh, if anything, may be slightly preventive, um, because cartilage joints, like everything else, benefits from being used, right? And so physical activity actually helps promote strong and healthy joints.

We used to think that it just caused them to wear away, but actually...

I don't know what to believe anymore.