What explains the association between muscularity and leanness?

Being muscular and lean is a fitness and health goal for many people. Interestingly, muscularity and leanness seem associated. For example, highly muscular, transgenic mice (e.g. Mstn and Akt1 mutants) typically have less body fat than wildtype mice. Similarly, young adults and bodybuilders with more muscle growth and/or mass are on average leaner than elderly individuals or hypogonadal men. What can explain this association between muscularity and eanness? Here, we propose that a hypertrophying skeletal muscle undergoes a cancer-like metabolic reprogramming which is similar to the Warburg effect. As a consequence, hypertrophying muscles take up more glucose and channel some of this glucose into anabolic pathways such as nucleotide-RNA/DNA and amino acid-protein synthesis. As a consequence of the increased muscular glucose uptake, less glucose is available for lipid synthesis, resulting in organismal leanness. Here, we will discuss data of 14C-glucose tracer and enzyme manipulation experiments that support the idea that hypertrophying muscles indeed increase their glucose uptake to support anabolism.      «

Being muscular and lean is a fitness and health goal for many people. Interestingly, muscularity and leanness seem associated. For example, highly muscular, transgenic mice (e.g. Mstn and Akt1 mutants) typically have less body fat than wildtype mice. Similarly, young adults and bodybuilders with more muscle growth and/or mass are on average leaner than elderly individuals or hypogonadal men. What can explain this association between muscularity and eanness? Here, we propose that a hypertroph...     »