When your muscles give up amino acids to keep your brain fed
Hungry for your alanine: when liver depends on muscle proteolysis.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
Alanine from muscle—not fat—is the key driver of glucose production during prolonged fasting.
Most people assume fat breakdown (lipolysis) is the main energy source during fasting, but this study shows muscle-derived alanine is the bottleneck for keeping blood sugar up—even more critical than fat.
Practical Takeaways
If you're fasting for health, understand that some muscle loss is biologically expected and protective for brain function.
Not medical advice. For informational purposes only. Always consult a healthcare professional. Terms
Surprising Findings
Alanine from muscle—not fat—is the key driver of glucose production during prolonged fasting.
Most people assume fat breakdown (lipolysis) is the main energy source during fasting, but this study shows muscle-derived alanine is the bottleneck for keeping blood sugar up—even more critical than fat.
Practical Takeaways
If you're fasting for health, understand that some muscle loss is biologically expected and protective for brain function.
Publication
Journal
The Journal of clinical investigation
Year
2019
Authors
Theresia Sarabhai, M. Roden
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Claims (2)
When you go a long time without eating, your muscles start sending a chemical called alanine to your liver, which uses it to make sugar so your brain doesn’t run out of fuel.
When your body is low on energy and can't switch easily to burning fat, it starts breaking down muscle instead — even though it would be better off burning fat.