Tonight I'd like to talk to you

about an experiment I did a few years ago,

that improved my life in so many ways.

However, before getting into the details,

I wanted to take you on a trip,
and photography can help us, to Africa,

to try to understand a bit
the context of this whole experiment.

Just imagine these four hunters

moving through a typical
Savannah scenario.

They are on the hunt.

They are following a herd
of enormous herbivores, called kudu,

and specifically a much larger one
that left the group.

They are putting him under pressure.

The human being evolved
for resistance race;

a race that is not too fast,

but that can go on for a very long time.

The hunters are putting him
under pressure,

and the kudu - unlike human beings -

cannot regulate his body temperature;

and because he is a large herbivore,

his intestine does not allow him
to breathe correctly on the run.

The fate of the kudu
is unfortunately marked,

because at some point
it will have to stop,

otherwise its heart would burst
due to the rise in temperature.

So the hunter,

with just a simple pointed wooden shaft,

can end the life of this large herbivore.

Even if this is a cruel scene,
it does not happen often.

It is difficult for the hunters
to carry it out.

Today our guys will take home
about 38,000 calories

to share with the rest of the village,

women, children
and less fortunate hunters,

for that day.

I spent ten years in Africa,
in Capetown to be precise,

where I worked in a center
for population genetics,

and together with other researchers,
I became passionate

about the lifestyle
of these hunter-gatherers,

who are still present
in different parts of Africa,

so also in South Africa,
the state of Lesotho;

and Botswana, Namibia and Tanzania.

And so we often spent time with them

to try to understand
their lifestyle, their eating habits,

their movement patterns
throughout the day.

We had incredible experiences:

I remember we used
to follow them in the hunt,

in their gatherings, all day long,
maybe a 38-degree hot day,

with our super technological shoes

and Camel Bags
full of water, mineral salts

and maybe the latest
generation of supplements,

but it was practically impossible
to keep up with them.

Sometimes we had to sit
in the shade of an acacia,

and while I watched them
disappear on the horizon,

I wondered if they weren't
really superior beings,

I mean really incredibly strong people
from all points of view,

also considering how stressful
their daily lifestyle is.

I then returned to Italy

and decided to start this experiment,

because something didn't add up.

From this slide you can see

that some agencies, such as FAO,
ENSA or the American FDA,

suggest the correct intake of calories

to maintain body homeostasis
and good health.

If we look at it,

everyone will find their range,
according to age and sex,

somewhere around 2,600-2,800 calories.

As far as I was concerned,
something didn't add up.

While living with them,
they didn't have those daily calories.

Yes, if the hunt was successful,

surely there were even more than that,

but it wasn't always the case.

So I decided to start an experiment
that lasted for months.

I greatly reduced

the amount of suggested calories.

I made a food plan

that got as close as possible
to what I had seen

and I followed it for a while.

From a hematological perspective,

I monitored all
the parameters that came out,

taking samples every three - four weeks,

in a laboratory,

and trying to see the changes

in blood glucose, azotemia,
cholesterol, creatinine

and all the other factors
that are influenced by diet,

one way or another.

Plus, I also tried to monitor
how my body changed

in terms of lean mass, fat mass,
visceral fat and body hydration,

and obviously I kept a daily journal

to see day by day

how I was reacting mentally,

how my moods and energy levels were.

I carried out this experiment.

It was not easy at first -
my wife knows something about that -

because moods change very very often,

energy falls, and so it also has
an influence on your work.

But I wanted to look beyond the horizon;

I tried to move forward,
despite a lot of people said to me,

"What are you doing?

You're decreasing your calories
and increasing your physical activity:

that's not good, it's wrong."

I went further, tried to continue,
and after a while something changed.

I remember it was friday,
because I was keeping a journal.

I woke up,

and felt an energy
I hadn't felt in a long time.

My sense of smell and taste
were completely altered for the better.

I could feel everything around me
in a 360 degrees fashion,

as though I were experiencing
the real "here and now".

I was not happy,

so I tried to involve, at the beginning,

a bunch of crazy friends,

who said, OK, come on,
we're right behind you.

I also gave them a plan
with the same concept:

lower by 1000 calories
their daily nutritional intake.

And with them I monitored,
using specific questionnaires,

a whole series of parameters.

Then I went from friends to acquaintances,

and we really increased in number.

Some people wanted to try it
just for the sake of challenge,

at least for a while.

We eventually became so many.

I collected all this data,

and although obviously
with different timing,

eventually everything converged

into the same feelings I had experienced:

a general sense of well-being and health.

These are parameters

that perhaps may not make sense to you,

but make it clear

that when the body
undergoes caloric stress,

something happens;

it is like an awakening, inside our cells,

of genes that had been hidden and dormant

for hundreds of thousands of years.

So I tried to go a little more
deeply into the topic,

and through PubMed ,

which is a database where you can find

all the research done
by laboratories around the world,

I looked for ones

that had somehow studied deeper
and for a much longer time,

the difference between
our society's lifestyle

and that of hunter-gatherer populations

still in place around the world.

And there were -

This is one of the graphs
that basically shows

caloric diversity from plants and animals

across the different populations.

Essentially, I found
three main differences.

One is caloric regime;

another is caloric expenditure,

the amount of calories burned in a day;

The third, perhaps most important thing -
that struck me so much -

is the very presence in our society

of a whole series of degenerative diseases

that are statistically increasing
in the population,

even in the youngsters -
take obesity, for example.

These diseases are completely unknown

in these hunter-gatherer populations.

So I wondered, what if these calories
are the real culprit?

If we look at this graph, 1990 to 2015,

the caloric intake worldwide
has increased exponentially.

I am one of those
who did not raise his hand before,

when the math teacher
asked who was good at it.

So if we want to, we can do an experiment:

take out our cell phone,

and go to the calculator application.

Ok? Let's put in 1000 calories.

We multiply that by seven,
one for every day of the week,

and then by four,
one for every week in a month.

And then we go on, by 12,

and we get to 336,000 -

Then let's put in 20 years.

That gets us to six million calories.

I want to leave you with this thought:

what if these six million extra calories
were the unexpected cause

for these diseases

and do not allow us to age
in a healthy manner,

and prevent us to become
like those hunters,

with all that great energy we have?

Thank you for your attention.

(Applause)