Calorie Restriction Makes Middle-Aged Muscles Younger

Calorie restriction, long believed to increase the lifespan of animals, mainly rats, could also be good for your muscles–if you’re middle-aged. How do we know? Because researchers at Chang Gung University in Taiwan thought that if calorie restriction could help reprogram metabolism, that could have a major benefit for aging muscles in which cellular metabolism is impaired, which is to say all muscles over a certain age. The American Physiological Society reports that the researchers focused on two pathways that produce energy in muscles, glycolysis (sugar metabolism) and mitochondrial oxidative phosphorylation in both young and middle-aged rats that were fed a normal diet or a calorie-restricted diet. In the 14-week study, rats on the calorie-restricted diet were given a 10 percent calorie restriction in the first week, 25 percent restriction in the second and 40 percent restriction for the remaining 12 weeks. The control rats received no calorie restriction. Ready? The envelope please….. After 14 weeks, the researchers found that the middle-aged rats had less muscle mass than the young rats did. No surprise there. However, while 14 weeks of calorie restriction did not significantly affect the middle-aged rats, it reduced muscle mass in the young rats. Calorie restriction slowed the glycolytic rate in the muscles and increased the cells’ dependency for OXPHOS versus glycolysis in older rats, which is linked to improvement of normalized muscle mass. The big news? The team also found that 14 weeks of calorie restriction reprogrammed cellular metabolism, where the relative contribution of OXPHOS and glycolysis in muscles of middle-aged rats with restricted calories was similar to that in muscles of young rats. And that’s a good thing.