-Three, two, one. Action!
CHRIS: Since I was playing Thor...
...I've definitely ate a lot more food than I used to.
Each meal is about 1000 calories.
Ice cream.
Big juicy steaks.
Goes straight in there.
Burgers, pad Thai, pasta, ribs.
Sausage rolls, pizza, cake, donuts, hot dogs.
When it comes to food, I'm like a starving hound.
Only less picky.
I mean, I do know that what I put into my body is important,
but what I didn't know is that the best thing I can eat
if I wanna live a long and healthy life is nothing.
Absolutely nothing.
Well, at least that's what this guy says.
Longevity expert, Dr. Peter Attia.
Thank you very much.
-We'll make this our last supper. -Our last supper.
For the next step in my quest to live longer and better,
he wants me to go on a fast. It's basically water
and zero calories for four days.
Thank you... very much.
Thank you.
-Right.
Yeah, good thing I got to kick it off with a hearty last supper.
Six shreds of lettuce and a carrot.
-Hmm. -Look, I'm gonna do it with you.
-You are? -And... Yeah.
It makes it a lot easier to go through this with somebody else.
-So... -Okay, good.
-Good, we'll suffer together. -Yeah.
-We will.
I've definitely gone a day without food before.
I think I get pretty cranky when... ...I've missed a meal.
Certainly, detrimental to my happiness.
So, it's a pretty long time, why four days? Why not...
-Why not longer?
I mean, what is the benefit with four days? Why that number?
Three to four days is probably that window at which we do enough
to change how your body is interacting
with the absence of nutrients to basically do kind of a reboot
-on your system. -Oh, really?
You think I'm gonna be able to hold it together?
You reckon, in your experience, you see a lot of people,
the first time they do it, succeed?
In the next four days, there is no doubt in my mind,
there will be a period of time in which you feel sluggish or...
-Tears? -Yeah.
-Emotional. -Kinda grumpy, grouchy, whatever.
But, you know, if you really stop to think about it,
this idea that we kind of live today
where we're sort of surrounded by unlimited access to food
and we can eat three meals and snack in between them,
that's a relatively recent addition to our species.
-Right. -And our ancestors would've gone days
without food all the time,
and not only did they have to do that, they had the ability to,
in a period of starvation, actually go out and hunt.
Right. I'm done. I have nothing left, except for one tiny little carrot.
You gonna finish that last piece left of lettuce?
Though, what about dessert? We get dessert or not?
-No.
Starting to think, this could be the most difficult four days of my life.
In truth, I think Chris will find this hard.
But I've been practicing periodic fasting for many years, and in doing so,
I've realized that the key is staying busy.
So I've thought of an entirely appropriate challenge
to help distract Chris from his hunger. I want him to do what his ancestors did.
I want him to hunt for his next meal.
But not on land. Instead, in the ocean.
So, the plan is, that after four days without food...
we're gonna head for the Great Barrier Reef.
I'm gonna be armed with a lungful of air...
and a speargun...
I'm gonna try and dive 30 feet to the ocean floor...
in search of a fish.
So, there's no pressure at all.
Thanks a lot, Pete.
This is day one of the fast.
I had a good sleep, I had probably seven... seven hours.
I did dream about fasting,
which was weird 'cause I wasn't in a fasted state.
Fed the kids bacon and eggs this morning, that was a little tempting,
but it's early days and I don't feel a huge threat
at this point of breaking my four-day fast.
I'm gonna get rid of the dog though, just in case he does...
-...eat it.
The dog will start to look like a roast chicken or something, right?
Yeah, yeah. No, we wouldn't eat her, unless we really had to.
At first, Chris will feel fine. He'll be working off the energy
from his last meal. But once that's gone, he's gonna start to feel a lot worse.
But I'm gonna want him to stick with this,
because, of all the things that we can do to impact Chris's longevity,
periodic fasting may be one of the more effective.
My food contains glucose.
The fuel that feeds the trillions of healthy cells in my body.
But that glucose also feeds something else...
zombie cells.
Old, damaged cells that have lingered beyond their useful life.
By spewing toxic sludge, these zombies infect other healthy cells,
speeding up the aging process.
Everything from hair loss and wrinkles
to the onset of arthritis, cancer, and dementia.
But what scientists have realized is that when we fast and cut off
the supply of glucose,
that zombie army is starved of energy which saps them of their power.
-It's long-term gain
for short-term pain.
For a food lover like me, lots of pain.
Yeah, I'm hungry.
-We are not gonna make it.
And by "we," I mean me and my best mates.
If anybody can help me get through this, they can, so I'm very, very pleased
and thankful that they've agreed to fast with me.
We're buddies from high school...
-Yeah. -...primary school to Chris.
-I'm Aaron. This is Luke. -Yep.
And now we work for Chris.
-So we're paid friends, really. -Yes. With benefits.
-With benefits, and, yeah... -We're a little family.
We're a little family.
CHRIS: Having a bit of moral support could be good.
Are you doing it all the way? Aaron, you're doing four days.
-Yeah. -Yeah.
-No. -No, you're gonna try.
Yeah, I'll try.
-He loves his food. -The angriest he's ever got at me
-was because I bought him too small...
...a steak once, in London.
He almost punched me out 'cause it was like that, and he was like,
"Look at the size of me. Why would you buy me that steak?"
I mean, he's not gonna do four days.
I'm cracking.
We're days away from eating, not, like, hours.
It's not like we can go home and smash a big bowl of spaghetti.
Forget pasta, our next meal, with a bit of luck, is a big, juicy fish.
But if I'm gonna be the designated fish catcher...
I'll need some serious dive training.
So, Peter has hooked me up with someone with a remarkable set of skills.
I'll give you a brief demo. I'm gonna start with a really big exhale.
-Wow.
-Huge expansion there. -Okay.
That was incredible.
CHRIS: Tanya Streeter is a breath-holding phenomenon.
She's a ten-time free diving world champion...
and can hold her breath for an amazing six minutes.
What we do as average human beings, is we breathe in the top part
of our chest, but you're not getting a lot of oxygen into your blood like that.
There's a greater capacity in the lower part of your lungs,
and you can't access that unless you relax your abs.
You basically learn to stick your stomach out as you breathe in.
-All right, how're you feeling? -Ready to set some records.
Let's do it.
So, is that the goal, the orange thing there?
Sure, there and back, man.
And what's that, about 50 meters?
-No, that's about 100 meters. -Oh, is it?
Be rather claustrophobic under there.
Yeah. We've linked up a guideline, 'cause it's pretty dark,
but it gives me an opportunity to see what you're made of,
-mentally as well as physically. -Okay, we'll see.
All right, whenever you're ready, Chris.
It was really poor visibility and instantly, my lungs are burning.
I hear in my head...
that I should give up and I'm running out of air.
And I'm trying to override that 'cause I know
that there is a lot more oxygen in my lungs than you'd think.
And surely, I must be there by now.
-Almost halfway. -I don't think so.
-Not even close. Twenty meters. -How many meters was that?
I don't think you quite made it 20.
Yeah, I'm a little disappointed.
Turns out, I was under for a whopping 27 seconds.
I'm actually quite surprised how ineffective and useless
my free diving skills are.
I know I can hold my breath on land for a few minutes, but, in the water,
when you're kicking and using up air and energy,
it's... it's just a whole different story.
Diving for my dinner is gonna be harder than I thought.
Speaking of food...
CHRIS: ...I don't even like broccoli.
And even though I've got homework to do...
without mealtimes to punctuate the day, time just seems to drag on.
It's, uh, almost dinnertime, and this is the worst I've felt.
Feel pretty light-headed... ...super weak and incredibly hungry.
-I feel tired. I didn't sleep very well.
I woke up a lot feeling really hungry
and then, um...
I... You know, feel empty, empty of food.
Almost as if I'm empty of, like, energy. Feel very flat.
Now, cooking this. I feel hungry.
Why can't you eat?
'Cause I'm not supposed to eat.
For how long, Dad?
Four days, bro.
Why?
I'm not even remotely tempted by this delicious, crispy bacon and eggs.
The second day of a water-only fast is an especially difficult day.
And the reason for this is that the body's primary reserves of glucose,
which are kept in the liver and in the muscles,
are starting to get rapidly depleted. And as a result of this,
Chris is feeling really tired and groggy.
But it's important for him to understand that this is okay,
because there are some people who routinely do this
and not only do they not starve, but they actually manage to thrive.
Hey... You missed...
Listen son,
if you can't hit the target,
the village won't eat.
Try again.
I'll try my best Dad...
Yeah, well done.
Isafiri is a member of the Hadza tribe.
He's a hunter.
We are hungry,
and we have run out of food.
Yeah, okay.
I will hunt tomorrow.
I will catch something big.
ISAFIRI: Being hungry is part of life here.
Sometimes we don't eat for days.
But we are not afraid.
because I know we won't starve.
Look, we should hunt there...
Come around from the side.
Being hungry...
makes me a better hunter.
Even after days without food, people like the Hadza
are still able to find the energy to hunt...
Look, dik-dik antelop e has taken a poop.
...because when a person fasts,
when you stop eating...
I think he is close by.
...it reveals the body's superpower.
CHRIS: When food is plentiful, our body stores excess energy
in the form of fat under the skin and around the internal organs.
When food is scarce...
that fat is sent to the liver...
where it's turned into an alternative fuel source called a ketone.
And it's these ketones which provide the emergency power source.
Not only for our bodies, but also our brains.
Along with an energy boost,
it seems ketones also sharpen mental focus.
Heightening the ability to see, hear...
and sense things in the environment...
that we normally wouldn't be able to perceive.
And ketone production ramps up...
just when a hunter needs it most.
The dik-dik is in there...
When you're getting closer,
your mind becomes alert to the wild.
The animal is your only goal.
Yes. it's a dik-dik.
We got it, we got it!
Everyone is happy.
when I bring home meat.
Our children
and our wives are happy.
Everyone is happy.
Ketones help the Hadza hunt when food is scarce.
And I'm pretty sure I'm gonna need some ketones of my own
if I'm gonna catch a fish in two days' time.
Little prick here.
Didn't hurt that much.
So, I'm checking ketones on two different meters.
Mmm.
They're in pretty good agreement at about one,
and over time, this will go up.
-There's more of them in my system now? -Yeah.
Or I'm producing more?
Exactly. Actually, around ten times more.
-And that's pretty low. -Right.
But hopefully today, tomorrow is when we'll start to see that transition
-where once you get over... -Yeah.
...two and into three, that's when you start
to kinda feel, like you're in the Matrix a little bit. You kinda seeing things
-a little bit different. -Yeah.
And what about the zombie cells?
Do you think my body's getting rid of them at the moment?
You're in the process of starting that, yeah.
-I... I think that comes in hand... -Good to know.
...with this transition to, uh, ketones,
and so, as the body starts sort of adapting to what's going on...
-Hmm. -...it's gonna start to reprioritize
and hopefully, it's knocking those guys out.
Good.
CHRIS: So, the war on zombies has begun...
but no ketone boost yet.
Which is a little worrying 'cause I'm off for more dive training.
Can't say I'm swimming in energy.
-I'm... My ability to speak is...
...rapidly declining. How do you guys feel?
Yeah, it's kinda peaks and troughs, isn't it?
-It is a definite a roller coaster. -It's like... It's a real...
It's a roller coaster of emotions. Uh-huh.
At the moment, I'm up, but there will be
-a time tonight when I'm down. -Hmm.
So, another Peter and Tanya training gig.
This time, underwater hockey.
They say it's gonna help me catch a fish.
-Hey, guys. -Hey, how's it going?
CHRIS: They also think, maybe it'll help keep my mind off the fast.
Well, it ain't working.
What else would you wanna do when you're fasting, tired, and starving?
Learn a new sport.
And nothing against underwater hockey, it's cool, but right now,
I just wanna eat.
Now, it's rough down there, but it's actually really good
for spearfishing. There's this sudden burst of energy, there's...
-Yeah. -You know, you don't know
when you're gonna have to dive, so you have to be super, super efficient.
-Oh, okay. -Okay?
Yeah.
Peter's playing for the reds.
Me for the blues. Number seven.
And my co-fasting best buddies, cheerleaders.
I feel like I'm watching my son go off to battle or something. I'm nervous.
-I'm real anxious. -I'm just worried about...
I'm worried about that because without that...
-We don't have a job. -...we don't have a job, so...
-We can't really... -Look after his face, please.
Don't touch his face, please.
Things don't start so well.
Ooh! Oh, oh, oh, oh. He's taking a beating.
Now, holding your breath is one thing...
but doing it while being pushed and shoved, and thrown around, and so on,
it's just a whole other thing.
It's pretty intense.
My need for air is overpowering.
If that puck was a fish, I wouldn't get anywhere near it.
Oh!
-Well done, Peter.
Good goal.
Half time, and it couldn't have come quick enough.
-How are you doing? -It's exhausting.
-I know. -Just trying to work out,
you know, when to conserve your energy, and when to dive, and make sure
you dive when the puck's coming as opposed to waiting under there
-and then by the time it gets there... -Yeah. Yeah. No, no!
-...you've got nothing left. It's like... -Yeah. No waiting.
But you got all the oxygen you need,
-so it's mental. Your stamina becomes... -Yeah.
...really mental at this point.
-Sure. Yeah.
Okay? So, just try to take some long, slow, deep breaths. So...
-Through your mouth.
-Do you feel better? -I feel good.
Okay, good.
-Okay.
CHRIS: I don't know if it's the half time coaching
or something else...
but I feel a little different.
My need for air is less urgent.
I feel more efficient in the water.
More aware of the other players around me.
And I'm focused on the puck.
And I feel a slight surge of energy.
Just enough...
to score.
-How do you feel? -I feel all right now.
-Yeah. -I feel much better than I did
-prior to playing. -Me, too.
Yeah. Why is that?
I think we're probably making more ketones at the moment,
our bodies are trying to ramp up production.
-It's basically saying... -It thinks... thinks we're hunting..
-Exactly, it's like... -Yeah.
..."Hey, they're... they're hunting. They're getting us food." Um...
I wouldn't be surprised if in an hour or two,
-we feel a little worse. -Yeah.
'Cause it'll realize, "We haven't got the food."
-"We've been kinda let down,"
and... and then, sort of, that production level
will come down a bit.
That doesn't help though, does it?
Oh, for heaven's sakes.
Just as I was beginning to feel a bit better...
-Oh. -They're doing it on purpose.
A familiar feeling returns.
-See, now I'm hungry again.
Still, at least my best mates are fasting with me.
And they never let me down.
-Hey, Chris! -Hey!
What the...
Sorry, mate, we couldn't do it. This is so good.
Are you
Come and have a slice, mate.
Two minutes ago, I was like, "It really helps the guys
"are doing it with me, you know, 'cause I'm like...
"I'm like feeling sluggish." I'm like, "Oh, I feel bad."
But then I'm like, "Oh, actually, they're laughing..."
-"...and I gotta keep it up."
You know, "We're all in this tog... together." That was three minutes ago.
And I'd love to tell you it's not that good,
-but it's honestly the best thing ever. -Mm-hmm.
-What, I thought you were fasting? -That's what I said.
Both of them were fasting. I said to them, like, I... like, I... like, I...
Just have a smell of that.
-Cool. -I gotta say, I really thought
you were gonna hang tough.
I was gonna, but then this is the best milkshake I've ever had.
-Good luck finding... -Oh, my God.
I can smell the pizza. I'll just go away. I can smell it.
CHRIS: Great, my best buddies have bailed, and just as Peter predicted,
the ketone pick-me-up has gone, and I feel terrible.
Okay, so this is, uh, day three.
Feeling pretty weak. Didn't sleep very much last night.
I feel like my sleep's getting worse and worse.
You know, last night was really hard, giving the kids dinner.
They had, um, delicious, like, roast lamb, and vegetables, and... and fruit, and...
and I saw a chocolate brownie in there somewhere.
Multiple occasions, I... I... I... I thought about just ripping that food
straight out of their hands. Feel pretty weak trying to walk up
the stairs, trying to walk down the hall, I feel like it's tough to catch my breath.
Uh, but, you know, day three, and, um...
I guess we're almost there. It's only...
12, 48, I don't know, I can't even think. Like, I... Don't know.
I'm losing it.
I'm trying to get my ketones going again by working out, but I'm feeling nothing.
Oh, and did I mention that I'm feeling really, really hungry? Hmm?
I don't think Chris has found this to be a pleasant experience at all.
-But a big part of fasting...
...is understanding why you're doing it.
And that's the key to tolerating this thing.
It's being able to focus on the motivation behind the fast.
One of the benefits is, you have a family.
-Yeah. -And you can sort of see
how much you enjoy that, and that's kind of the anchor,
-I think, um... -Yeah.
You can actually look into the eyes of the people for whom it matters
the most to you.
Yeah, sure. I like that motivation, you know?
Anything that stops me thinking about food
is sort of a... a good thing at this point, so...
Asking Chris for his very first fast to go as long as four days is a big ask.
But I really need him to continue now.
Because once a human goes three days without food,
we think some remarkable biochemical changes take place
that have significant longevity benefits.
CHRIS: Remember those toxic zombie cells aging my body?
Well, they're not the only things getting dealt with.
Even inside my healthy cells, there's wear and tear.
But scientists think that without food to process,
those cells can switch into repair mode,
fixing damage, cleaning up garbage, nipping any problems in the bud.
With the zombies in check and the rest of me in tip-top condition...
the future looks healthier and also longer.
Science is only just beginning to understand
the longevity benefits of fasting.
In fact, we're just catching up with the cultures and religions
that have placed fasting at the center of their practice for millennia.
Today is a beautiful day.
CHRIS : Retired teacher Todesso and his family
are celebrating Easter with a walk to church.
Papa, are we nearly there yet?
No, not yet.
But the church is three days away
in the holy city of Gondar.
Are you tired?
Yes I'm tired.
Don't be tired, be strong.
During their grueling pilgrimage,
the family eat absolutely nothing.
Fasting is very important to us,
it is a tradition handed down by our ancestors.
We fast to be closer to God.
Come on you two.
I'll be so happy when we get there.
I got you.
CHRIS: And joining her parents for the first time is daughter Helen.
The first day was the hardest.
I felt so weak.
My brain was telling me, "You can do this."
But my stomach was saying, "Bring me food!"
But fasting isn't just bringing them closer to God...
they believe it's bringing them health benefits.
Although my father is 75 years old, he is very strong.
I have never seen him sick.
He swears fasting is why.
I started fasting when I was seven.
And I've been doing it for 68 years.
It keeps me feeling healthy.
I have never been affected by a common cold,
or any other disease.
Look, Gondar is just over the mountain.
HELEN I can see it...
Come on.
I can smell incense.
Easter isn't the only time
Ethiopian Orthodox Christians fast.
In fact, they observe up to 250 fasting days a year,
during which they vary their practice, sometimes eating nothing,
and others, restricting how much or when they eat.
All these smells So much food.
Gondar is an amazing place.
There are many ways to go about fasting.
There are countless protocols.
But remember, they all have one thing in common.
They reduce the number of calories we consume.
And in a world where so many of us are over-nourished,
this is an essential part of how we can go about living a longer,
-healthier life.
I am very proud of myself for doing the fast.
I will do it every year.
I will only stop fasting on the day I die.
Two hundred and fifty fasting days a year.
CHRIS: Makes me think, "Surely, I can go another 24 hours...
"can't I?"
Struggling, struggling I'm struggling
I'm on the ferry to our dive base in the Great Barrier Reef...
...and I could really do with a ketone pick-me-up.
-I had a little, like...
...like an hour ago, a little burst of energy.
I thought, "Oh, this is good." Now...
CHRIS: So, this is it.
The last day of the fast, and the day I'm supposed to catch dinner
for me and Peter. What could possibly go wrong?
So, how are you feeling this morning?
Uh, pretty weak. Pretty... Pretty low energy.
I feel like I've just rolled out of bed.
You know, even though you don't feel it, at the microscopic level,
inside your body, there's a war going on.
And that war is being won by the good guys.
Hmm.
And that's the real reason we're doing this.
-Yeah. -All right, let's see what we got here.
CHRIS: So, I could live longer, but right now,
I'm not sure I'm gonna make it through the day.
So, remind me, where were my ketone levels yesterday?
So, yesterday, you were at about one.
-Now, you're almost at two. -Yeah.
-When the ketones get closer to three... -Yeah.
...is really when that switch is flipped.
-But once you get in the water... -Mmm.
...I think it's gonna shoot up.
I don't wanna put any pressure on you, but I'm hungry, man.
And seeing as I can't catch a fish with a spear and you can...
I kinda need you to come through on this. The stakes are high...
-Yeah. -...for the both of us.
-All I heard was "steaks." Edible kind. -Yeah.
The stakes are high, and not just for today.
By fasting, Peter says I'm fighting
those zombie cells and repairing healthy ones.
And that could mean a longer, healthier life.
But first, I've gotta go hunt down that fish.
-Welcome aboard. -Thank you so much.
If only I can find the energy.
I'd love some ketones right now.
PETER: Chris's ketone levels have risen, which is what we wanna see.
I know he isn't feeling it yet, but just as in the underwater hockey,
the effort of hunting is going to ramp up these evolutionary adaptations
in his body, giving him the edge he needs.
-Ooh. -Stretch your legs.
-I know. -Just made me really light-headed.
CHRIS: I'm feeling really vague...
and kinda absent from everything.
I was expecting this big flood of energy that he keeps talking about.
It's not kicking in though.
Don't overdo it.
Blackout, or what we refer to as a loss of motor control, is...
is very real.
Yeah. So what are the symptoms
that I'll feel if I need to wave the flag
-of retreat?
Um... There's a fine line between feeling completely empty and done,
and really feeling almost like your head is shaking
-and your hands are shaking a little bit. -Hmm.
I mean, if it's a blackout, you're not gonna feel anything at all
and you're not gonna remember anything at all.
So if I take one look at you and your face tells me that you're done,
doesn't matter how driven you are, you're done and we're gonna get out.
Sure.
Let me know how you're feeling and just don't push it too hard.
-I'm hungry. -I know.
I'm exhausted already.
All right, it's go time.
CHRIS: Right, I'm in.
I know I have enough oxygen in my body...
but I look up and the boat seems so, so far away.
I feel like I'm losing all focus...
and suddenly the urge to breathe is overwhelming.
How do you feel?
Yeah, I just went down there and then went,
"Oh, I need to breathe soon,"
and then I felt really weak, and I thought,
-"There's no way I can do this, ever." -Yeah.
I'm feeling so tired. And the energy boost that Peter promised me...
nothing.
So after a brief moment, I go again.
But this time, I start to feel a little different.
As I'm going down, it's like I'm tuning into the ocean.
I can hear every sound.
Time seems to slow down.
And I start to feel a surge of energy.
And then, I see a fish.
-Nice work. You did it. -Got one. Peter...
-...your dinner.
-Hey, nice one.
-Awesome job, man.
He looked great.
You looked great.
-Whoo!
CHRIS: We did another test after the hunt, and the surge of energy,
turns out my ketones had shot up to nearly three.
So it worked. The science came good.
-Not a bad catch, huh?
It's an amazing catch, man.
It smells good, looks good.
But, you know, I'd have been happy eating vegetables right now
-if that's all we had. -I know.
Boom!
There's all this anticipation and buildup, it almost felt guilty
or like I was doing something wrong if I was gonna take that first bite.
This will be the nicest "break-fast" I've ever had, I think.
-So who eats first? -The man who caught the fish.
We didn't dive into it like we'd expected.
It's unreal.
Ceremonial and...
and important and special.
Mmm.
Don't know whether to laugh or cry.
That was the best meal I've ever had, I think.
Sometimes when I'm eating that first meal after a fast,
I have this tiny, tiny piece of regret.
And I think, "Should I have gone another day?"
Do you feel any of that?
-Not a teeny, tiny piece. -Not that much of it?
-Nothing. No. -No.
Absolutely not.
No, right now, mate, I'm in the middle of heaven.
-Oh! It's amazing. -Mmm.
Mmm. Well, I'd like to make a toast...
to the ocean, for feeding us this fish...
and you, for making me suffer through four days of fasting
to really, really appreciate it.
I'll make a toast to your 90-year-old self and those great-grandchildren
-you're gonna be playing with. -Cheers.
So, that's it, four days, no food. Didn't crack. Would I do it again?
Uh... Can't believe I'm saying this, but yes.
From now on, I do want fasting to be a part of my life.
Oh, oh. Look at us going at it. Yeah!
That's not to say I'm never gonna go out with a bunch of friends.
-It's so hot.
Basically eat everything on the menu, like a starving hound.
-It's so hot!
I'll definitely do that.
I'm just looking at it. I'm just looking. I'm not eating anything.