The Claim
A three-day water-only fast increases plasma beta-hydroxybutyrate concentrations by more than fivefold in healthy adults, indicating a metabolic shift from glucose to fat-derived energy sources.
What the research says
Supports is higher
Support is ahead, but a single strong opposing study can change this.
These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.
After three days of drinking only water, healthy adults show more than five times higher levels of beta-hydroxybutyrate in their blood, which reflects a switch in the body’s primary energy source from glucose to fat.
See the scientific wording
A three-day water-only fast increases plasma ketone bodies (beta-hydroxybutyrate) by more than 5-fold in healthy adults, indicating a metabolic shift from glucose to fat-derived energy sources.
When no food is eaten for three days, the body uses up all stored sugar in the liver and muscles. Without sugar, insulin levels drop, signaling the liver to break down fat into fatty acids. The liver then converts these fatty acids into ketone bodies, which become the main fuel for the brain and other organs.
What the research says
1 studyAfter three days of not eating anything but water, the study found that the body made more than five times as many ketones — which are fat-based fuel molecules — proving it switched from burning sugar to burning fat.
Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.