Here's more evidence to support moderating one's calories: a BBC article that describes a study in the Proceedings of the National Academy of Sciences, that found that a calorie restricted diet in 50 elderly volunteers improved their memories significantly. These same volunteers also had "fewer signs of inflammation" and decreased levels of insulin.
Want to live longer, feel better, have a smaller ecological impact, and now remember more? Eat fewer calories--and make those calories as nutritious, local, ecological and low on the food chain as possible. See the earlier essay on Right Diet for more on how to do this.