Читать книгу The Obesity Code Cookbook - Jason Fung - Страница 16

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introduction

Insulin is a fat-storing hormone. There’s nothing wrong with that—

that’s simply its job. When we eat, insulin production goes up, signaling

the body to store some food energy as body fat. When we don’t eat, insu-

lin production goes down, signaling the body to burn the stored energy

(body fat). Higher-than-usual insulin levels tell our body to store more

food energy as body fat.

Everything about human metabolism, including body weight,

depends upon hormonal signaling. A critical physiological variable such

as body fatness is not left up to the vagaries of daily caloric intake and

exercise. If early humans were too fat, they could not easily run and

catch prey, and they would be more easily caught themselves. If they

were too skinny, they would not be able to survive the lean times. Body

fatness is a critical determinant of species survival.

Figure 3: Weight Gain or Loss Depends Upon the Hormone Insulin

As such, we rely on hormones to precisely and tightly regulate body

fat. We don’t consciously control our body weight any more than we

control our heart rate or body temperature. These are automatically reg-

ulated, and so is our weight. Hormones tell us we are hungry (ghrelin).

Hormones tell us we are full (peptide YY, cholecystokinin). Hormones

increase energy expenditure (adrenalin). Hormones shut down energy

expenditure (thyroid hormone). Obesity is a hormonal dysregulation of fat

Fed State

Storing Food Energy

Burning Food Energy

Fasted State

Eat Food

Increase

Insulin

Store Sugar in Liver

Produce Fat in Liver

Burn Stored Sugar in Liver

Burn Fat in Liver

Decrease

Insulin

No Food

“Fasting”