Dr. Jason Fung

So they're regaining all that weight.

And then they're still saying, hey, I'm eating so much less than I used to.

Yes, you are.

But you didn't do it right because you didn't fix the hormonal issue, which is that body fat thermostat.

And that's why you see these sort of naturally lean people, right?

You see them all the time.

They eat whatever they want.

They tell you, I don't really look at what I eat, right?

I eat what I want, what I want.

And they're really skinny.

Well, that's because they have that thermostat.

They do what they want because the thing is that as soon as they gain weight over that threshold of sort of skinniness,

their body shuts down their hunger.

That's the thermostat pushing you down.

Their thermostats are set really well.

And maybe it's genetic, maybe it's whatever, but keep in mind that in the 70s,

people's thermostats were obviously working very well because there was just not a lot of obesity.

So then you have to say, what's changed, right?

And what are the hormones that are involved?

And insulin is one of the main ones, right?