The Study
Effect of starvation on human muscle protein metabolism and its response to insulin.
This study watched how 8 healthy people's muscles reacted when they didn't eat for a few days and then got a little insulin. It saw changes, but didn't compare them to people who ate normally, so we can't say insulin definitely caused the changes — just that they happened together.
Analysis score
Maximum 44 for a cross-sectional study.
Where the score came from
When you fast for 60 hours, your muscles start releasing more amino acids because they're breaking down protein — but insulin can still stop this breakdown, even though it can't help your body use sugar anymore.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 526 / 100
Quality score
Snapshots of a population at a single point in time, or descriptions of small groups. Can identify correlations and prevalence, but cannot determine cause and effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1Yes — this means your body preserves muscle even during fasting if insulin is present, which is important for understanding how the body protects muscle during starvation.
- 2After 60 hours of fasting, muscle amino acid release increased 2-3x.
- 3Insulin cut this release by about 40% by slowing protein breakdown, not by building protein.
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
The American journal of physiology
Year
1990
Authors
D. Fryburg, E. J. Barrett, R. J. Louard, R. A. Gelfand
Related Content
Claims (4)
During short-term fasting, insulin stops the breakdown of muscle protein into amino acids even when it fails to promote glucose uptake, showing that its ability to protect muscle from breakdown remains intact.
During 60 hours of fasting in healthy humans, muscle releases two to three times more amino acids because protein breakdown increases, while protein synthesis remains unchanged, resulting in net muscle tissue breakdown.
In healthy humans undergoing a 60-hour fast, insulin decreases the release of amino acids from muscle by 40% by reducing the breakdown of muscle protein, and does not increase the rate of muscle protein formation.
After sleeping for 8 hours without eating, the amount of amino acids in skeletal muscle decreases.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.