Ghrelin
A digestive hormone secreted mainly by the stomach that stimulates appetite, often called the "hunger hormone"; the counterpart of leptin.
Ghrelin is the “hunger hormone”. Produced mostly by the stomach when it is empty, it sends the brain the signal “it’s time to eat”. Its levels rise before meals and fall afterwards. It is the counterweight to leptin (satiety).
An original angle (beyond hunger): ghrelin does more than make you hungry. It:
- Stimulates the secretion of growth hormone
- Influences reward and motivation (it makes food more “desirable” and activates the dopamine circuit), which is why it is so hard to resist when you are hungry
- Plays a role in memory and learning
- Takes part in stress management
The trap of restrictive diets: when you lose weight, ghrelin rises lastingly (the body “demands” its lost weight back) while leptin falls. This double hormonal signal creates intense, persistent hunger that largely explains weight regain after a diet (the yo-yo effect). It is not a lack of willpower, but a hormonal adaptation you have to work against.
Ways to modulate ghrelin:
- Protein suppresses it effectively (lasting satiety), hence the value of a protein-rich breakfast
- Fibre and bulky foods distend the stomach, reducing ghrelin
- Sleep: deprivation raises ghrelin (more hunger)
- Avoid fast sugars, which cause rebound hunger
Understanding ghrelin helps take the drama out of post-diet hunger and build filling meals.