[Rhonda]: Can you explain for people who just aren't very familiar with time-restricted
eating or time-restricted feeding, as we call it with animal research, like, just what is
that and how does that actually affect your metabolism of glucose and fatty acids and
amino acids?
[Satchin]: Yeah, so let's kind of step back and ask how does it relate to circadian rhythm,
or the daily rhythms.
So if we think of our daily health, our health, our personal sense of how we feel healthy
changes from time to time throughout the day.
So, for example, in the morning when we wake up, being healthy means you're feeling much
rested and you're full of energy to start the new day.
You're feeling actually much lighter, you should not feel that full stomach or grogginess,
and have a good bowel movement.
And then throughout the day being healthy means not feeling too hungry, so having some
food in your system, and then being productive throughout the day.
And then towards the end of the day being healthy actually means having taken a walk
or something so you are not feeling really...you haven't moved all day and you're not feeling
that sense of being constrained in a place.
And at night time before going to bed being healthy means feeling really sleepy, so that
as soon as we switch off the light and get into the bed we fall asleep.
So in this way you can see that being healthy, this definition is very different at different
times of the day.
And a lot of it actually has to do with physiology or metabolism.
So in the morning feeling lighter and not groggy and not having a food hangover means
you have already gone through...hopefully somebody has gone through 10 to 12 or even
14 hours of fasting, not having food in the system, so that your body has metabolized
all the food and has processed it and your gut has also gone through rest.
And then towards the end of the day when you're going to hit the bed, if we have food in our
system, what happens is blood flow is directed towards our stomach to digest the food and
absorb it, so core body temperature remains high.
So not having food for two to three hours before going to bed actually helps us to go
have that deep sleep, sound sleep throughout the night.
So in this way now if we back up and think, "Okay, so when should we eat?," then it makes
sense that, well, after waking up maybe give one or two hours before we start eating, and
then before going to bed at least three to four.
Depending on what your metabolism, two to four hours before going to bed we should stop
eating.
So that brings up an eating window of, say, up to 10 to 12 hours max when we should be
eating so that we have that personal sense of being healthy throughout the 24 hours.
So in animal studies what we have done is we ask a very simple question.
If we take animals and give them food just like most labs do, they have food in the hopper
they can eat whenever they want, and we calculate how many calories they eat.
And then we take another group of mice and then give them the same number of calories
and from the same source of food, whether it's high carb, high fat, high fructose.
It doesn't matter, we have to give the same source of food, same number of calories to
the second group.
And they have to eat all that food within 8, 9, 10, or even 12 hours.
Then we consistently find that the mice that eat all their food within this 8 to 12 hours
window are healthier than ad libitum fed mice.
So that led to the term, what we call time-restricted feeding, where the timing of food when we
eat is restricted or you define it and stick within it.
Not caloric restriction, where you have to count calories and restrict it.
So in this way it becomes very easier because you just have to...we all know how to manage
our time, on a daily basis we are always dealing with time.
So it becomes easier because if we start eating around, say, 8:00 in the morning and, based
on our lifestyle, we can do 10 hours eating, then I'll have my dinner, say, around 6:00.
So that's the concept of time-restricted eating or time-restricted feeding.
[Rhonda]: And, yeah, I think that having the time where you just sort of say, "Well, I
should stop eating by, you know, 6:00," or, you know, kind of having it so you don't have
to constantly each day think about it, like, "When did I eat my first meal?," or," When
did I take my first bite?"
If you kind of just have this general schedule where it's, at least during the workweek,
you know, it's easier.
[Rhonda]: And then another thing I must point out, that in our animal experiments, when
we do these experiments, suppose we say eight hours, we've fed the animals for eight hours.
And then every week we measure their food intake and some weeks they might eat less.
And then we immediately change that schedule to, say, eight and a half hours or nine hours
the next week to make sure that they actually eat the same number of calories.
So moving this needle by one hour actually is not that detrimental.
It still gives them the benefit.
And we have also asked another question, so in animal experiments.
In weekend we let them free, they can eat whenever they want.
And they definitely go outside of a 12-hour window, they eat almost throughout the night.
But still that two days of binge eating can be counteracted by if they stick to 8 to 9
or 10 hours during the weekdays.
So that also gives us hope that perhaps in humans occasional eating maybe once or maybe
maximum twice a week can still be tolerated.
[Rhonda]: That's good to know, I guess a lot of people would be happy to hear that.
[Satchin]: Yeah.
[Rhonda]: What do you do?
So for your typical workweek and then weekend schedule, like, what's your time eating window?
[Satchin]: Yeah, so it's...
You know, I travel a lot, too, but I...what I've found is if I stick to maximum 12 hours
window, then I actually feel much better and more energetically, I sleep well, and I feel
lighter, and I'm still productive throughout the day.
So I start, say, somewhere around 7:00 or 8:00 in the morning, and then I stop around
5:00 or 6:00 in the evening.
And I also try with different types of diet once in a while.
One thing with many people who are new to time-restricted eating, or eating or feeding,
is when they start it they feel hungry.
And what we have found is while having a fiber-rich diet or a protein-rich diet or a slightly
higher fat-rich diet actually helps to go through that longer time without food.
And slowly you also get used to it.
And all of these actually increase your nutrition quality because you're staying away from simple
sugar and high glycemic food and you're leaning more towards food that takes a longer time
to digest or longer time to absorb.
So that helps.
And that way my diet, both diet quality and also the duration have changed.
And I usually stick to 12 hours, and in many cases I kind of try to stick to 10 hours.
[Rhonda]: Oh, me, too.
I try to stick to 10.