Via PLoS Medicine, a look at the benefits calorie restriction (CR) brings to mitochondrial function - and hence to your long-term health: "A calorie-restricted diet provides all the nutrients necessary for a healthy life but minimizes the energy (calories) supplied in the diet. ... 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 induction of these efficient mitochondria in turn reduces oxidative damage in skeletal muscles. Consequently, this adaptive response to caloric restriction might have the potential to slow aging and increase longevity in humans as in other animals. ... CR and CR [plus exercise] both increased the number of mitochondria in skeletal muscle. Both interventions also reduced the amount of DNA damage - a marker of oxidative stress - in the participants' muscles." The normal caveats are given, but the more we learn about the mechanical operation of calorie restriction, the better it looks, given that it costs nothing but thought and time to try.