Dr. Jason Fung

And the reason is actually basic physiology.

It's actually medical physiology, like first year medical school stuff.

When you don't eat, what happens in your body from a hormone standpoint?

is that your insulin is gonna fall.

You're gonna allow your body to start using the calories that are in the body.

At the same time, other hormones go up.

So the sympathetic tone goes up, which is your fight or flight response.

Your cortisol levels go up because again, it's an activation and your growth hormone goes up because those hormones are gonna start telling your body to start pulling calories out.

So you're actually activating yourself.

Think about in the wild, if you see a hungry wolf, is that wolf just sort of, you know, all like lethargic?

No, he's activated.

He's actually more dangerous than any other wolf, as opposed to say a lion who just ate.

Because when you just eat, you just want to lie there.

You know, you want to digest your food.

You have no energy.

So people say, well, your metabolic rate is going to go down if you fast.

No.

The truth is actually the opposite.

It goes up.

Yeah, the whole idea that you need to eat as soon as you get up is just false.