Video summary
Dr. David Sinclair emphasizes that his core advice regarding longevity has remained consistent since 2019, with no need to retract any findings from his book or research. He argues that the traditional marketing of three meals a day, particularly the idea that breakfast is the most important meal, is largely a construct by food companies like General Mills and Kellogg's rather than a biological necessity. Humans are not evolutionarily designed to eat consistently throughout the day; our ancestors were often hungry for long periods. Consequently, Dr. Sinclair advocates for intermittent fasting, typically limiting intake to one or two meals daily, noting that while he personally enjoys food, his body adapts well to extended periods without it. He suggests that viewing hunger as a normal state rather than something to be constantly suppressed aligns better with our biological adaptations.
The primary benefits of this approach become particularly noticeable after the initial three days of fasting, when the acute feelings of hunger subside and individuals begin to feel amazing. Dr. Sinclair explains that prolonged fasting triggers a process called chaperone-mediated autophagy (CMA), which acts as a deep cellular cleanse by removing misfolded proteins that contribute to aging. During this time, the body shifts its energy source from glucose stored in the liver to ketones produced from fat stores, providing a steady and efficient fuel for the brain without the typical fluctuations of energy crashes or brain fog associated with regular eating patterns. He monitors his progress using continuous glucose monitors and smart scales to ensure he maintains optimal weight and muscle mass, adjusting his exercise routine if necessary to prevent lean tissue loss during extended fasts that can last up to two weeks.
However, Dr. Sinclair stresses that this regimen is not suitable for everyone, particularly those who are already underweight, elderly, or have specific health conditions, and it requires careful management of hydration and essential nutrients. To avoid deficiencies such as scurvy while fasting for extended periods, he takes a comprehensive daily supplement regimen containing vitamins like B and C, minerals, probiotics, and other necessary nutrients. He views this supplementation not as "bro-science" but as a scientific necessity to ensure the body has everything it needs during the fast. His routine involves drinking plenty of low-calorie fluids like tea and occasionally consuming non-nutritive items like celery, but he relies heavily on his curated supplements to maintain health without relying on solid food for an extended duration.
Ultimately, Dr. Sinclair concludes that the key to maintaining a consistent health routine is simplicity and avoiding unnecessary complexity, much like playing golf where one should focus on the essential elements rather than getting distracted by minor details. He believes that making health practices easy to follow increases the likelihood of long-term adherence, which is crucial for achieving longevity benefits. While he acknowledges that his ability to fast for two weeks is unique due to his specific physiology and disciplined approach to supplementation, he encourages listeners to find a fasting protocol that works for their individual bodies without overdoing it or risking muscle loss. The goal is to harness the metabolic advantages of fasting while ensuring nutritional adequacy through targeted supplementation and mindful monitoring of one's physical metrics.
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lifestyle stuff. Yeah. Last time that we
were talking, it was all about calorie
restriction and primarily fasting as a
route toward calorie restriction.
How should people eat if they want to
live as long as possible now with your
2026 data?
>> Well, actually what I've been saying
actually on on my podcast for now what 4
years it hasn't changed and my book
lifespan which came out we were talking
about when we first met in 2019 it
nothing in that book I've had to revise.
It's all consistent. So there's no
retractions from the book in 2019. No no
and my labs never retracted anything and
at this point never been proven wrong
which is a blessing and I knock on touch
on wood.
But that's good news which means that
the things that I've said before people
can go back and learn still.
If this is the first time you're seeing
me you know let's let's start. So the
the main things about fasting are we
know from animals
and some human data but mostly from
animals that if you restrict how often
you eat
and to some extent how much you eat you
get longevity benefits
um
and we can talk about
protein ratio to carbs to fats that's
also a whole big debate as you know.
But generally I I like to eat one meal a
day
maybe two if I'm being social but not
three. I think three meals a day plus
snacks is marketing.
Um breakfast being the most important
meal of the day was General Mills I
believe one of those companies Kellogg's
perhaps. But this is you know it's all
marketing humans are not built to eat
that consistently. I don't think cavemen
were sitting around eating their big
breakfast saying what are we going to
eat for lunch? I think
you know maybe if they just killed a
mammoth but generally they were pretty
hungry a lot of the time and our bodies
have adapted to that. We're not meant to
always be satisfied and so I try to be
hungry and if I gain a little bit bit of
weight sometimes I travel and I eat well
and Serena and I uh, we do uh, sometimes
love to eat.
I'll come home from travel and just I
won't eat for 3 days. Sometimes 2 weeks
I can go without food. It's not a big
deal for me.
>> without food?
>> Yeah.
Okay.
I might munch on a on a piece of celery
or something, but that's not really
nutrition. I will drink a lot. I'll
drink a lot of low-calorie, zero-calorie
drinks, a lot of tea, that kind of
stuff. But I can go without food for 2
weeks. It feels great after the first 3
days I'm over the hunger feeling.
Um, I can see on my monitor, which
I've got one on here.
>> CGM?
>> Uh, the CGM. Yep. Uh, I can see the
great impact it's had having on my body.
I can monitor it on my rings. I do blood
tests, which is important. You don't
want to just guess what's working, what
isn't.
But yeah, I know 2 weeks sounds like a
lot.
But
>> It's It doesn't sound like a lot. It is
a lot.
>> It is a lot. And I'm a regular guy. I I
I'm not
like some people that spend millions of
dollars on their body and and measure
everything.
I'm kind of lazy. I I don't like being
hungry. I like food. I like to snack. I
I like to stay up late. I'm a typical
hedonist if you let me go.
Um, and actually up until a year ago, I
actually hadn't fasted more than 24
hours.
I just couldn't do it. It's like, "This
is
painful."
Um, and I'm stressed. So, if I'm
stressed, I'm going to eat. Um,
but what I've learned over this past
year is I can go beyond 24 hours. And
once I'm over 3 days, something kicks
in. Actually, we know molecularly
there's something called
chaperone-mediated autophagy or CMA,
which is the deep cleanse of these
misfolded and modified proteins that you
want to get rid of for aging or slowing
aging.
And, uh, after those 3 days, you know, I
I start to feel amazing. My mind clears.
Um, I don't feel bloated at all.
Um, I don't even have to go to the
toilet that often except for all the
tea, but you know what I mean.
And, uh, yeah, I feel energized. And I
I'm measuring myself, so I'm making sure
I'm not overdoing it. This is not for
everybody. If you're skinny and you've
got belly any fat or you're elderly,
it's not for you. But for me, I gain
weight and muscle pretty easily. I can
fluctuate. And so I watch my weight come
down. I've got uh a scale that measures
my weight. Um it's I don't know if I can
measure say the name or if it it's
forbidden, but um I do like the Withings
scale cuz I
>> Smart scale links to the phone.
>> Yeah.
>> It'll get your composition as well if
you hold the handle.
>> Yeah. And And I've had one since 2013,
so I've got all this data on my body
weight and composition, which is
awesome. And I'm trying to maintain that
at the optimal level over these last 13
years.
>> I'm This 2-weeks thing is blowing my
mind. What are you running on after 10
days? Are you Why is malnutrition Are
you supplementing with with vitamins and
stuff so that you don't get scurvy?
>> Yes, I have. I am. I'm glad you said
that, Chris, cuz it's important to say
I'm a scientist about this. I'm not just
willy-nilly giving up everything.
>> celery and green tea, surviving for 2
weeks, just bro-sciencing it.
>> Well, no, I'm not doing that. I uh
The reason I'm using my hands is I
travel and at home I have a little carry
pack with vitamins, supplements, um and
medicines that I've been using and know
very well what I need. I Every morning
it's a symphony of supplements and
medicines, actually. I know what my body
needs. I know what what works. Uh so I
do that. So that's not Not anybody can
do that. So it's really important if you
do fast for long periods, make sure you
enough hydration, very important. We
know that. But also I'm making sure that
I'm not deficient in any minerals or
vitamins, and so I'm I'm taking in
things like vitamin B,
uh vitamin C as well, and some nutrients
that I know
I can become deficient in.
>> What do you think's happening inside of
your body after
from day four until in the day 14?
What's what's going on?
>> Well, we we know, actually. Um
not from measuring me, but we know from
many years of study what happens to the
human body.
Uh the first 24 hours you you're going
to uh use up a lot of
the the sugar and then the glycogen in
your liver. What I like to think is my
liver knows how to
steady my glucose and give me the right
amount of glucose far more than my mouth
does.
My liver smarter than my eyes and my
mouth.
And anyone that's fasted knows that your
blood sugar if you're eating's like this
and you go, "Oh, energy. Oh, brain fog.
Energy. Brain fog. Oh, I'm sleepy in the
afternoon." That's our normal life. If
you're fasting, your liver just puts out
just the right amount of ketones for
your brain.
Um or you can drink some some ketone
drinks. Um or
uh it's making glucose or both. Your
brain is loves ketones. And uh if you do
it too long,
you will start to lose muscle. So, I'm
working out more than I do normally to
make sure I don't lose any weight. And
so, that scale will tell me if I'm
losing lean mass, which I don't want to
do. And I make sure that I don't lose
it.
>> Is that not a concern to do with your
gut? Is that not Is that Does that not
need to be transit through the digestive
tract? I don't know what happens if
nothing passes through your stomach for
2 weeks.
>> Yeah. Well, I can tell you your stool
changes. Uh there's very
>> it does. It turns [ __ ] invisible.
>> Yeah, right. There's phantom poo as it's
a bunch of gas coming out. Um so, yeah,
it That's what I meant. I'm not on the
in the bathroom as often. It's actually
much more productive.
Um unless you're productive on the
bathroom.
>> find that I do I do find that the
biggest uh obstacle to my productivity
is the bathroom, actually.
>> [laughter]
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