Cutting calories could be key to keeping muscles young: study
It takes considerable self-discipline, but sticking to a hypo-caloric diet could benefit aging muscles, according to a study by researchers in Taiwan who used rats as their subjects.
Calorie restriction has long been associated with reduced risk of cardiovascular and other diseases in humans and extended lifespan in animals.
In addition, previous research has shown it can improve overall health, and this particular study cites calorie restriction as the only non-pharmaceutical and non-genetic strategy to do so.
Cutting calories encourages muscle cells to make the best use of antioxidants, thereby avoiding damage caused by free radicals, according to recent research, having the effect of a reset button for the metabolism.
Springboarding from this notion, the research team hypothesized that aging muscles -- in which the cells' metabolisms are frequently impaired -- could benefit significantly from the restorative effect that calorie restriction offers the metabolism.
In the 14-week study, the rats -- some of which were young, others of which were middle-aged -- saw a 10 percent calorie reduction the first week, a 25 percent restriction the second, and a 40 percent restriction for the next 12 weeks.
A control group saw no changes in the amount of calories in their diet.
"We investigated whether CR [calorie restriction] reprogrammed muscle metabolism and whether this improvement was associated with the observed increase in muscle mass," wrote the researchers. "In addition, we examined whether the CR-induced changes were age-dependent."
At the beginning of the study, the middle-aged rats had less muscle mass than the young rats, yet 14 weeks of calorie restriction reduced the young rats' muscle mass but did not effect that of the middle aged rats.
In fact, cells in the middle-aged rats saw a reduction in the rate of energy production by means of sugar metabolism, also known as the glycolytic rate.
This encouraged more cells to engage instead in a metabolic pathway called mitochondrial oxidative phosphorylation (OXPHOS), an effect that's beneficial because OXPHOS is linked to improvement of normalized muscle mass, according to the study.
Indeed, 14 weeks of calorie restriction had reprogrammed cellular metabolism in the middle-aged rats, which took on the same proportions of glycolosis -- and OXPHOS -- as their younger counterparts had before the study.
The study was published in the American Journal of Physiology - Endocrinology and Metabolism.
