Absorption from the last meal ends
Over the hours after eating, the small intestine finishes absorbing the last meal and no longer adds glucose to the blood.
A 24-hour fast — 0 seconds
A representative healthy adult's fuel supply over the 24 hours after the last meal.
The hormonal balance shifts
Insulin falls back from its post-meal level and then stays low, which lets the liver release glucose rather than store it.
Stored fat supplies more of the energy
Fatty acids released from stored fat circulate and are oxidised for energy, and the liver converts some of them into ketone bodies.
The liver draws on stored glycogen
The liver breaks down its glycogen store to keep releasing glucose into the blood, and that store falls steadily across the day.
The liver makes new glucose
As glycogen falls, more of the glucose the liver releases is newly assembled from smaller building blocks such as lactate, glycerol and amino acids.
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Time elapsed
- Last food · 00:00:00
- Absorption tapering · 01:00:00
- The liver takes over · 04:00:00
- Glycogen drawn down · 08:00:00
- Both glucose sources contribute · 12:00:00
- Stored fat more prominent · 16:00:00
- A full day without food · 24:00:00
Happening now
The last meal has just finished; absorption is still under way and insulin is near its post-meal level.
Explore the mechanism Absorption from the last meal ends
Over the hours after eating, the small intestine finishes absorbing the last meal and no longer adds glucose to the blood.
Evidence for this step
Insulin typically rises with the last meal, falls back over the following hours, and then generally stays low and fairly flat for the rest of a day-long fast. moderate · View sources
In a representative healthy adult, blood glucose typically drifts modestly downward across a day without food and generally stays inside its usual range rather than falling steeply. moderate · View sources
- Whole-body context: 50%
- Liver: 55%
- Pancreas: 80%
- Small intestine: 85%
- Skeletal muscle: 55%
- Bloodstream: 70%