Why hunger peaks then passes—even if you don't eat.
What the evidence says
- Ghrelin rises before meals (preprandial) and falls after eating; secreted in pulsatile manner (~8 peaks per 24 hours)1,2
- During fasting, ghrelin shows increase and spontaneous decrease at customary meal times — even without food2
- Overall decrease in ghrelin levels observed during fasting — ghrelin adapts2
- The fasting ghrelin pattern mirrors the fed pattern, showing that the brain (cephalic control) primarily drives meal-initiation timing — not just gastrointestinal signals2
- Early time-restricted feeding (6-hour window) made hunger more "even-keeled" — reduced diurnal amplitude by 10 mm (p=0.006) — and decreased mean ghrelin by 32 pg/mL despite longer daily fast; the benefit is appetite stabilization, not metabolic boosting (24h energy expenditure unchanged, p=0.55)3
- Ghrelin rises before voluntarily initiated meals even without time or food cues, with preprandial increases across varying intermeal intervals (320-425 min); hunger scores and ghrelin showed parallel temporal profiles — supporting ghrelin as an endogenous hunger signal, not just a conditioned response4
- This explains why hunger comes in waves and passes without eating, and why fasting gets easier2