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.
Book about food and dieting by James W. Clement.
Explains NAD+ synthesis is circadian, and how SIRT1 is critical in ISCs - 2016 Roy Walford lecture
Rapamycin might not be an alternative for calorie restriction
Lifespan.io (LEAF) - 27-Jan-2021
Failed to mimic dietary restriction pathways on extending lifespan in progeroid miceRead more...
Metabolic confusion diet probably has same effect as intermittent fasting
The Conversation (UK) - 08-Dec-2020
Metabolic confusion diet may have other health benefits than just weight lossRead more...
Extending the healthspan without restricting calorie intake
Medical News Today - 13-Sep-2020
Metabolites vital for pro-longevity effect of calorie restriction can help develop drugsRead more...