Canada.com notes the results of a study to published this month: "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 ... From a young age, the rats ate about 40 per cent fewer calories than normal, although their diet was rich in nutrition. ... elderly rodents on [calorie restriction] 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. ... 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."