Research
Mixed
Metabolic flexibility—the ability of skeletal muscle to switch between fat and glucose oxidation in response to fasting and insulin—is a key determinant of insulin sensitivity and leanness.
To improve metabolic health, focus on building aerobic fitness and maintaining leanness. These factors enhance your muscles' ability to switch between burning fat and glucose, which is crucial for insulin sensitivity. Simply losing weight without improving fitness may not restore this flexibility.
GoodSupportsHIGH confidence
These findings support the concept that the capacity of skeletal muscle to oxidize fat under appropriate physiological conditions is related to leanness, aerobic fitness, and insulin sensitivity.
Why this rating
Based on consistent in vivo human studies and cultured myocyte data cited in a high-impact journal commentary.
Source
Skeletal muscle fat oxidation: timing and flexibility are everything
D. E. Kelley · Journal of Clinical Investigation · 2005
DOI 10.1172/jci25758
narrative_reviewCited 296×
Read the paper DOI resolved against Crossref · corpus check 2026-06-10
Related findings · Mixed
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