[Rhonda]: The other thing that is sort of on this whole fasting versus TRE topic that
gets asked a lot that I have to ask you has to do with coffee.
Actually, specifically caffeine, like black coffee.
So without any cream or any calories or anything like that.
So caffeine can start things, like the clocks in your liver?
[Satchin]: Yeah, it resets the clock.
Because the clock is always running, it just resets.
[Rhonda]: It resets it, okay.
So a lot of people in the intermittent fasting community, they do a lot of fasting, whether,
you know, they're fasting for 16, 24 hours, 48 hours, but they drink caffeine and they
notice that they lose weight.
And so they say, "Well, I'm still getting results."
[Satchin]: Yeah.
[Rhonda]: You know, "So it's fine, I can drink my black coffee."
[Satchin]: Yeah.
[Rhonda]: You know, obviously someone that's fasting for 48 hours, it's very different
than doing the TRE schedule where you're eating for 10 hours a day or 11 hours a day, and
then fasting for, you know, 13 or 14 hours every night, right?
[Satchin]: Yeah.
[Rhonda]: So if a person, for example, that wakes up in the morning drinks black coffee
at 7:00 a.m.
They wake up, have some black coffee at 7:00 a.m.
But they don't eat anything, they don't eat their first bite of food until...
[Satchin]: 10:00 or 11:00.
[Rhonda]: Yeah.
Yeah, something.
Then when do they have to stop eating by?
Like, is it when the coffee started or is it when they ate the food?
[Satchin]: Yeah, so this is a question we also get through the app a lot.
And we actually posted a blog on our website.
So here is a very different thing.
So since we look at circadian rhythm as a whole, it has a sleep component, food component,
exercise or activity component.
And we know that caffeine resets the body clock.
So, for example, drinking a cup of coffee is similar to having exposure to bright light
for an hour or hour and a half.
So that's just on the circadian clock itself.
Now the question is, "Well, will it reset that clock the same way if the coffee comes
in the morning versus evening or night?"
And we know that there is a term called phase response curve.
So that means the same light, it relates to light.
The same light will reset the clock differently at different times of the day.
During daytime when your system is expecting light, if you're in a dark room and we see
light it doesn't reset our clock.
But in nighttime it will reset our clock.
So we don't know what is the phase response curve for coffee, whether it resets much more
at certain times and less at other times.
The direct impact of coffee on clock is unknown.
Then the second thing that relates to coffee is sleep because coffee definitely suppresses
sleep in a lot of people, some people may be resistant.
And the reason why we drink coffee is we wake up, we get up from the bed, but we maybe are
still feeling sleepy.
We want to get that extra energy, that's why we drink coffee.
And along that line, of course, drinking coffee at night is a straight no-no because it will
have impact on sleep.
But in the morning we ask the other question, "Are you drinking coffee because you did not
rest well, you did not rest enough?"
So maybe that's why you need coffee to reset your mental clock, or brain clock, to start
it.
And sometimes it can be just a pure habit or addiction.
For example, I used to like coffee in the morning, and then I realized, "Well, let's
get rid of coffee.
What happens?"
Maybe for the first two or three days I got a headache, and then now I'm used to drinking
just hot water.
It's just the feeling of sipping something from a sippy cup.
It's almost like a baby sipping something from a sippy cup.
And I realized that that's what I was addicted to.
I can actually substitute coffee with hot water and nothing changed.
I still felt energetic after my hot water and I realized that that was my addiction.
[Rhonda]: After you got over the...
[Satchin]: After I got over the first two days of headache.
[Rhonda]: ...withdraw.
[Satchin]: Yeah, withdraw symptoms.
And then it's always [Inaudible] the question of metabolism.
When we drink coffee, is it going to trigger metabolism or certain things in our gut so
that the gut will think, "Well, now I have to start working, the rest is over"?
And we think that's where the metabolism or the function of the gut to absorb, or digest
this coffee, send that caffeine to liver, and then to brain does kick start right after
we drink coffee.
Because that's how we are feeling the effect of coffee in the rest our body, because the
stomach started working, it absorbed coffee, it sent it to liver, liver might have metabolized
it slightly and started to send it to the rest of the brain and body.
And then it gets back to kidney, it gets metabolized and excreted.
So then the question is, forget about circadian clock, now if we think about just metabolism
and, say, mitochondria function, or even, say, go back to autophagy, and then ask, "Is
caffeine breaking the fasting so that it stops autophagy, or it stops something else?
Or is there a crosstalk between, say, caffeine receptor and glucagon receptor so that it
does?"
No, fasting is kind of slightly over.
You may not be in 100% fast, but in 40% or 50% fast.
So that's where things become murky, so that's why we say, "Well, if you can, drink your
coffee within this 8-hour, 10-hour, it's better."
But at the same time we know, going back to the study that we discussed, Ruth Patterson
study, they did not consider coffee as food.
So when they considered 13 hours overnight fasting, that 13 hours actually included coffee
and tea.
So in that we know for cancer, reducing breast cancer risk, this 13 hours of fasting can
include coffee, black coffee, and tea.
So this is where things are really murky.
And we tend to error on the safe side, so we tell, well, if you can have that coffee
within your eating window, that's much better.
If you can't, then just have black coffee.
At least that will not trigger your insulin response or glucose response.
So that's what we do, we recommend.