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The Metabolism of Muscle
The Metabolism of Muscle

The Metabolism of Muscle

In a comment to Dr. Michael Eades’ post “Are we meat eaters or vegetarians? Part II” (21. September 2009, 22:32), Gabe says (at 22. September 2009, 20:26):
Thanks for the comments Mike. You know I had to try to check some numbers myself… though not very thoroughly tonight. I did find, however, a couple of references that suggest that muscle metabolic rate is indeed ‘not all that’, and it may be overestimated in most cases. In one reference (Am J Clin Nutr 2006;84:475–82) [http://www.ajcn.org/cgi/reprint/84/3/475], Robert Wolfe suggest that “every 10-kilogram difference in lean mass translates to a difference in energy expenditure of 100 calories per day, assuming a constant rate of protein turnover.” That’s only about 10 cal/kg muscle (or ~5 cal per pound of muscle!). The other reference, a bit older (Obes Res. 2001;9:331-336) [http://www.nature.com/oby/journal/v9/n5/pdf/oby200142a.pdf], the authors propose a classification scheme founded on body composition level (whole-body, tissue-organ, cellular, and molecular) and related components as the resting energy expenditure predictor variables. Rather technical but if some of the equations are applied to muscle, then we find that muscle the daily metabolic rate for muscle is just about 6 calories per pound per day, not very far from Wolfe’s predictions and very low indeed! I can see how this could lead to the notion of ‘exercising is a waste of time’. While the increase in metabolic rate is modest at best (or right out low…), at least is higher than the metabolic rate of a similar weight of fat, which is about 2 calories per pound per day. Perhaps the lesson is that the right kind of exercise (resistance in this case, and probably more on the heavier side of weight training) improves body composition by burning more calories than fat in the hours after exercise and by preserving lean body mass while dieting for weight loss. In any case, certainly there may not be such thing as three extra pounds of lean muscle burns about 10,000 extra calories a month as I seem to remember from “Power of 10: The Once-a-Week Slow Motion Fitness Revolution”. The Blog of Michael R. Eades, M.D. © mreades 2009
As in the previous post, we could not grasp these facts without…math!! (And physics. And chemistry. And philosophy.) How ubiquitous math is, but how perplexing it is that people don’t grasp how math useful is.

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