Rhonda: And you have a certain term, I guess. I don't know who coined the phrase, but it's called time-restricted feeding.

Satchin: Yeah.

Rhonda: And you've done...there's been experiments that you've done in mice where you've fed them various types of food.

Satchin: Yeah.

Rhonda: High-fat diet, high-sugar diet, normal chow diet, and you've restricted their time feeding, you know, during their, the nights, you know, the mouse day hours, which is actually the night because they're nocturnal, and you found, you know, some very interesting things. So, can you talk a little bit about those findings?

Satchin: Yeah. So what we have seen is when we, in experimental animals, if they don't have a clock, then their metabolism goes really weird. So just like I said, a metabolism works like this traffic signal in downtown, and if they're not timed properly, then there'll be disease. Similarly, for very long time we knew in the field that mice that don't have circadian clock because they lack a gene or have a mutation, they have various metabolic defect. They have obesity, diabetes, cardiovascular diseases, etc. We also know people who do shift work for a very long period of time, they are also highly likely to get metabolic disease, cancer, [inaudible 00:35:27]. So there was this idea that clocks are important. If we don't have a good functioning clock, then that's bad for us.

Then we went back and asked, "Okay, normal circumstances, what are the conditions that can actually break down our clock?" And what we found was when mice are given high-fat diet or any unhealthy food, then the food itself breaks down their clock. So they actually don't have a good eating-fasting rhythm, so the mice eat throughout day and night. And we knew that high-fat diet and high-fructose diet, high-sucrose diet, all of these diets that are used experimentally in laboratory condition gave rise to all this disease. And people always thought it's what and how much the mice ate that determined the disease. But what we found is, well, these mice are also not eating at the same time. So maybe when they eat also matters.

We did a very simple experiment where we took two groups of mice, completely identical set of mice, no genes were changed, no drugs were given, and one group of mice ate whenever they wanted to eat, and we...to begin to with to give them a high-fat diet. So they're getting somewhere between 45% to 60% of their food from fat or calories from fat. So that means it will be equivalent to humans eating all of their food from cheese, nachos, ice cream, or Western diet.

Rhonda: So they're getting fat and sugar.

Satchin: So they're getting fat and sugar all this time. And then other group got the same number of calories and the same type of food, exactly identical food, but they had to eat all their food within 8 to 12 hours in nighttime. So in some experiments we have done 8 hours, 9 hours, 10 hours, 12 hours, like that, and the most surprising thing is…and this is something that everybody, a lot of laboratories around the world do. There are 11,000 papers saying high-fat diet causes obesity. And we said, "Okay, so now we control for time." So since time was restricted, calorie was not restricted. So that's why we call it time-restricted feeding. And surprisingly, the mice that ate for 8 to 12 hours, they did not become obese, diabetic, and they had a normal liver function and they had normal cholesterol, etc.

And then in the next set of experiments, we exposed these mice to high-fructose diet, high-carb diet, high-sucrose diet, all kinds of diets either ad libitum, whenever they can eat, or they are to eat within 8 to 12 hours. And in most cases, we see the time-restricted feeding has huge beneficial impact. Even when mice eat standard diet, normal chow, which is supposed to be healthy, and mice actually eat most of their food, nearly 70% of food during night time. They eat a little bit during daytime, but if they completely restrict that to 8 to 12 hours, then their muscle mass goes up, their fat mass decreases, and they are more coordinated. So if you put them in a rotating drum, than they coordinate on the rotating drum for a long time.

So the bottom line is this time, so in these experiments where we kept what and how much they ate constant, the only thing that we changed is when they eat, then we see this huge beneficial impact, and that correlates with very robust clock in the liver, and in other metabolic organs.

And why this is important is two things. One is many of us have daily bad lifestyle. I won't say bad, but we don't have much control over what and how much food we eat. As soon as we get out of our home, all the food we eat outside we have very little control over it. So the only control we have, actually, is in our time. So, that's why we think this can be a good entry point to a better living by controlling time.

And then the second thing is it also doesn't take away this idea that nutrition doesn't matter, that quality doesn't matter, because even in our high-fat fed mice, we don't see they completely become normal just like the normal chow-fed mice. They're much healthier. So to have better health, you still have to change what and how much you eat, but timing becomes much easier to manage.

Rhonda: So you just covered so much. This experiment that you did right here, this publication, even before, you know, you've gone onto some small human studies, but this convinced me to do a time-restricted feeding schedule because, well, for a couple of reasons, but…so just, like, to reiterate, these mice that were fed a high-fat diet, they were fed the same amount of calories, but those that ate during their waking hours...

Satchin: Yeah, yeah, yeah.

Rhonda: ...so for mice, which is night within, I think, it was 12 hours...

Satchin: Yeah.

Rhonda: ...they gained…I'm sorry, they had 70% less fat mass.

Satchin: Yeah. So they had 28% less body mass total.

Rhonda: Right.

Satchin: And that change in body mass is mostly due to fat because they had 70% less fat.

Rhonda: That's amazing.

Satchin: Yeah, that's really...

Rhonda: Right there and they're eating the same crappy food, but they're eating it when their liver can process it the best, you know, when they're, you know, able to regulate their blood sugar, when they're able to oxidize fats, things like that.