Caloric Restriction
Extreme CR is a tedious and onerous way to extend human life expectancy, and we're not even sure that it works all that well in humans. Obesity is certainly life shortening, and that should be avoided. Cachexia (severe malnutrition), on the other hand, provides an even worst prognosis for life expectancy. When all is said in done, experimental animals on CR, like mice or monkeys, still die, even if they manage to live significantly longer than ad lib age-matched controls. So we should not lose focus on need for a fundamental understanding the genome/epigenome itself as the key to achieving indefinite life extension (what Dr. de Grey has dubbed "Escape Velocity").
