Dr. Jason Fung

It's the hormones.

Clearly, we have very clear evidence because that's what happens.

Sympathetic nervous system.

So the sympathetic nervous system is the fight or flight response.

It turns out that if you stimulate the sympathetic nervous system, it pushes your thermostat down.

You lose weight.

How do we know?

You can give people sympathetic agonists.

So in the 1960s, we used for weight loss amphetamines, which were called speed, right?

You know, lots of other problems with that, but it caused weight loss.

If a generation later, they use fen-phen, which is fenfluramine, phentaramine.

And again, stimulated sympathetic nervous system.

Or you use nicotine.

People who smoke, they lose their appetite, they eat less, and they lose weight.

It means you're pushing it down.

And the important part about the whole thing is not the specific drug, because obviously, I thought...

I'm not recommending people take speed and track and so on to lose weight.

But the point is that this whole thermostat is a hormonally mediated system.

Why?

Because everything in our body is mediated by hormones.