The only proven way of currently extending life expectancy in a variety of mammals is undernourishment (not malnourishment) but requires further study to see whether it has undesirable side effects.
Long lived species have less response to famine so, according to Aubrey de Grey, not likely to have a big impact in humans.
More info: CR Society International
Calorie restriction extends life of monkeys by 3 years – New Scientist – 17-Jan-2017
Trial in macaques has found that CR makes them live 3 years longer than normal – equivalent to 9 years in people.
There were also lower rates of heart disease and cancer.
About 10% life extension compared to 50% seen in mice.
Eating less may lead to longer life – Irish Times – 7-Apr-2016
Greater longevity for those who reduce their calorie intake.
Calorific restriction has been shown to extend lifespan in some species.
Professor Steven Austad of the University of Alabama at Birmingham says studies on members of the Calorie Restriction Society show they have reduced cardiovascular risk.
COMMENT: so maybe not extending maximum lifespan, just increase average life expectancy by not dying early of a heart attack?
Review of Mechanisms that Slow Aging from Calorie Restriction – Fight Aging! – 6-Jan-2015
CR changes near everything in the operation of metabolism and slows near every measure of aging making it difficult to figure out chains of cause and effect.
Does not repair of damage.
Review of recent studies includes:
Mitochondrial activity and ROS production are modulated by CR
Importance of membrane lipid composition on the CR effect
Antioxidant activities in ageing and CR
AMP-dependent protein kinase (AMPK)
… and many more.