#91 - David Zeevi

**Craig Cannon** (0:00)
Hey, how's it going? This is Craig Cannon, and you're listening to Y Combinator's podcast. Today's episode is with David Zeevi. David is a James S. McDonnell Independent Fellow at the Rockefeller University Center for Studies in Physics and Biology. He focuses on developing computational methods for studying microbial ecology in the human gut and in the marine environment, and its contributions to human and environmental health. He was also one of the authors on the paper Personalized Nutrition by Prediction of Glycemic Responses.
You can find David on Twitter at DaveZeevi. All right, here we go. So today we have David Zeevi on the podcast, and you are an author on many papers, but the paper that I initially contacted you about is called Personalized Nutrition by Prediction of Glycemic Responses. And this is a quick summary.
People eating identical meals present high variability in post-meal blood glucose response. Personalized diets created with the help of an accurate predictor of blood glucose response that integrates parameters such as dietary habits, physical activity, and gut microbiota may successfully lower post-meal blood glucose and its long-term metabolic consequences. Why did you start working on this?

**David Zeevi** (1:14)
So we got to see the amazing statistics on metabolic disease in the world. So right now, 4 out of 10 US adults are obese.

**Craig Cannon** (1:30)
And just to clarify, obese means what?

**David Zeevi** (1:33)
It means a BMI, a body...

**Craig Cannon** (1:36)
Mass index.

**David Zeevi** (1:37)
Mass index of over 30, which is actually not that bad, but it's still considered obese by the CDC. And that's 4 out of 10 US adults. Now, it was about 1 out of 10 in the 1980s, so it progressed massively. And this is based both on the World Health Organization and the CDC, the Centers for Disease Control.
1 out of 10 Americans are diabetic, and this is an awful disease. It's a lot of suffering. It's a lot of, you know, related complications, and it's a huge burden not only on people who have the disease, but also on healthcare systems. And I told you before, it's like $250 billion spent on diabetes and its related costs in 2012

**Craig Cannon** (2:27)
Yeah, annually.

**David Zeevi** (2:28)
So, yeah, so it's a huge deal. And it's widely accepted that nutrition is a major source of these diseases.

**Craig Cannon** (2:38)
Because diabetes was not nearly as prevalent in, for example, 1990

**David Zeevi** (2:43)
Right. It was not nearly as prevalent in the 1990s, 1980s, 70s. It was not as prevalent and neither was obesity. And when we came to look at it, we just tried to figure out what are the changes, what are the major changes that were done to our nutrition of the last 30, 40, 50 years or so. And we came up with four, five main changes. So, first of all, we started consuming much less fat. It was reduced from about 20% of our calories to about 15%. We started... So, having fat in your food is tasty and it's also very fulfilling and everything. And if you want to give food a taste without fat, you usually add sugar. So, sugar mainly took the place of fat in our diet.
So, there's a graph I sometimes show in lectures where you see the sugar consumption per capita per year since, I don't know, I think 1700 till today.
And the crazy fact is that the annual consumption in 1700 is the daily consumption today. So, we couldn't have evolved to undertake to treat this amount of sugar that's going into our system.
The other couple of things that have changed is that we consume much more additives with our food. It's much less food and much more industrialized. And the last thing is that meal times changed. We work in shifts, we have electric light, and that changes when we eat and our daily routine in general.

**Craig Cannon** (4:42)
Gotcha. And so, then this study, how are you actually measuring the effects of food intake?

**David Zeevi** (4:51)
So, this is also an interesting thing because we were thinking that if nutrition did cause this epidemic, what can restore healthy nutrition? And when you try to ask what's healthy nutrition, you can look at popular Time Magazine covers, for example, and we looked at that. And you can see that some of them say that saturated fats are bad for you, some say that fats are good for you, and some say that you should be vegetarian, some say that you should eat an Atkins diet. And there's a famous one which I really like from 1972 that says, eating may not be good for you.
But we thought, as scientists, that what you should eat is not a question of trend or passion or whatever, it's a scientific question, and we want to address it with scientific metrics. So we had to choose a metric that was specifically good for this question.