A successful diet may do more than trim the waistline.
University of Calgary scientists say old-fashioned calorie counting could also be the key to maintaining young muscles as we age.
In a study to be published this month in the Journal of Gerontology: Biological Sciences, the researchers found that elderly rats on a calorie-restricted diet had the muscle mass and function of much younger rats.
"It’s the equivalent of an 80-year-old rat with the muscles of a 20-year-old rat," said Russ Hepple, a University of Calgary physiologist, in an interview Wednesday.
The study examined rats bred at the U.S.-based National Institute of Aging. From a young age, the rats ate about 40 per cent fewer calories than normal, although their diet was rich in nutrition.
Hepple’s study the second in a series examining the effects of calorie restriction found that elderly rodents on the strict diet experienced only a 20 per cent drop in muscle mass and no loss of muscle function.
By contrast, rats eating a normal diet lost 50 per cent of their muscle mass and 50 per cent of their muscle function at old age.
"We know (calorie restriction) extends life span. What we’ve shown is it also maintains muscle function," said David Barker, a post-doctoral student who worked on the research.
Indeed, scientists have known for years that reduced-calorie diets extend the life expectancy of rats by as much as 35 per cent.
Hepple is still trying to understand why restricting calories helps aging muscles.
The study suggests restricted-calorie diets preserve the function of mitochondria which provide the body’s cells with energy as the animals grow old.
The diets appear to help the aging rats rebuild and replace muscle.
Although cutting calories had a profound impact on rat muscles, Hepple said he wouldn’t advocate the average person reduce their food intake by 40 per cent.
"The restriction of calories is so severe it’s impractical," he said.
Instead, he said humans need to eat a healthy diet, refrain from overindulging and remain active to maintain their muscles.
In the meantime, his research team will embark on further studies with antioxidants, exercise and gene therapy to see if factors other than fewer calories can lead to younger muscles in old age.
