It is important to take in adequate amounts of lean protein such as chicken, fish, lean red meat, egg whites, low-fat cottage cheese or a protein supplement.

CNN: How should I eat to build muscle mass?

It is also important to eat adequate amounts of high quality lean protein like chicken, fish, lean red meat, lowfat dairy or protein supplements like soy or whey, because your body's ability to absorb protein decreases somewhat with age.

CNN: Should I always lift to muscle failure when weight training?

This is the fact that the French tend to eat fatty diets rich in red meat but to have the survival characteristics of those whose diets are lean and vegetarian.

ECONOMIST: Abolishing ageing