A Little Less Means More
Even slight calorie restriction is good for you, as noted at ScienceDaily: scientists "have found that eating a little less food and exercising a little more over a lifespan can reduce or even reverse aging-related cell and organ damage in rats. ... even small reductions in calories could have big effects on health and shed light on the molecular process responsible for the phenomenon, which until now has been poorly understood. ... This finding suggests that even slight moderation in intake of calories and a moderate exercise program is beneficial to a key organ such as the liver, which shows significant signs of dysfunction in the aging process. ... feeding rats just 8 percent fewer calories a day and moderately increasing the animals' activity extended their average lifespan and significantly overturned the negative effects of cellular aging on liver function and overall health." File this under "how good health practices actually work."
Link: http://www.sciencedaily.com/releases/2006/05/060508165053.htm