Another round of calorie restriction research from PLoS Medicine: "Caloric restriction without malnutrition extends life span in a range of organisms including insects and mammals [and] delays the onset of age-related chronic diseases such as heart disease and stroke. There are also hints that people who eat a calorie-restricted diet might live longer than those who overeat. ... But how might caloric restriction slow aging? A major factor in the age-related decline of bodily functions is the accumulation of 'oxidative damage' in the body's proteins, fats, and DNA. Oxidants - in particular, chemicals called 'free radicals' - are produced when food is converted to energy by cellular structures called mitochondria. One theory for how caloric restriction slows aging is that it lowers free-radical production by inducing the formation of efficient mitochondria. ... The observed increase in muscle mitochondrial DNA in association with a decrease in whole body oxygen consumption and DNA damage suggests that caloric restriction improves mitochondrial function in young non-obese adults."