Definitely a lot more research required here but I think the intermittent fasting research is pretty interesting and promising. Particularly with the result that dietary restriction achieved by nutrient dilution rather than fasting didn't extend lifespan (Solon-Biet et al., 2014). Easy to imagine that our ancestors didn't have access to food all the time and our metabolisms are geared to fast periodically.
In the mean time I'll probably stick with the Michael Pollan approach to diet - 'Eat food. Not too much. Mostly plants.'
If looking into the state of intermittent fasting, the work of Valter Longo is probably a good starting point. His group is presently trying to get intermittent fasting past the FDA as a part of cancer treatments, which means he is doing more rigorous and more human-focused studies than most other groups I'm aware of.
Unfortunately "easy to imagine" doesn't imply "particularly plausible", although it's an association we all (including me) tend to make. It's easy to imagine that bloodletting is a useful treatment, or that $SOME_GROUP aren't as $SOME_CHARACTERISTIC as $SOME_OTHER_GROUP, but the number of such easy-to-imagine ideas that stand up to public testing by systematic observation, controlled experiment and Bayesian inference is extremely small.
So while I don't disagree that it's easy to imagine that our ancestors had intermittent access to food--men of the Piraha people in South America, who live pretty Stone Age lives, are apt to go without food for a day or two just because they can, for example--that doesn't go too far toward increasing the plausibility that such circumstances were common enough to have a significant evolutionary influence, particularly as the evidence for positive effects for women is somewhat weaker than for men, and pregnant and nursing women have more continuous caloric requirements than others (random site with some links on women's response to IF: http://www.marksdailyapple.com/women-and-intermittent-fastin...)
In contrast, we are pretty sure humans evolved as opportunistic hunter-gatherer-scavengers, able to survive on diets and dietary schedules that were extremely variable, from mostly plants in some places to mostly meat in others, and fairly steady food supply to fairly intermittent, all without there being a vast range of average lifespans between them. This suggests that our dietary optimum is broad and shallow, whereas a great deal of dietary research seems aimed at the belief that our dietary optimum is narrow and deep, so if we could just discover the precisely right diet we would live in good health for substantially longer.
This may be the case, but my personal bet is that in my lifetime a) no such discovery will be made and b) it will continue to be extremely lucrative selling this implausible idea to the public in various guises, from "superfoods" to weird eating patterns.
Of these, intermittent fasting seems at least to be a reasonably effective way of dealing with the caloric overabundance we live in the midst of in the West, and is also well within the (arguably very broad) envelope of our evolutionary adaptations. It is also at the very least benign and quite possibly marginally better than many alternatives.
I'm disappointed that the dietary interventions did not include a ketogenic diet as there has been recent evidence that such a diet is competitive with caloric restriction in terms of life extension (and would not suck so bad to actually practice).
For all we know, calorie restriction is effective because it is ketogenic almost by definition. It wouldn't be surprising considering how much overlap there seems to be between the benefits of ketosis and calorie restriction in general.
This paper summarizes a variety of promising research instead of specific diets. The first two sentences of the conclusion summarize it fairly well:
Recent and accumulating work in unicellular and invertebrate
model organisms, rodents, monkeys, and humans indicates
that diet has a much more pervasive and prominent role than
previously thought in modulating mechanisms of aging and its
associated diseases. More work is needed to understand the interactions
among calorie intake, meal frequency and timing, single-nutrient
modifications, the microbiome, and nutritional history
in modulating the key mechanisms that maintain cellular,
tissue, and organ function during aging
This paper seems to be a hodgepodge of anything that might have potential to extend life, but mostly calorie restriction. My take is that I'd rather not eat only 1,000 calories a day for the hope of living 2-5 years longer. Its just not worth it to me, especially when you understand the typical quality of life during those last couple years.
Interesting how there's so little discussion nowadays about dying with dignity, but tons of spilled ink about living longer. Quality of life is often dismissed totally or just seen is irrelevant to the research.
I find the teen and twenty-something crowd being big on this, but the 40 and over crowd being pretty lukewarm toward life extension. I imagine the latter crowd have seen their own parents and other close relatives reach end of life and pass away, and want nothing to do with extending those last few years.
It seems that dietary restriction can also improve quality of the final years. From the paper: '[Dietary restriction] can produce
substantial benefits with, for instance, 30% of DR animals
dying at old ages without gross pathological lesions,
compared with only 6% of ad-libitum-fed controls'
Lesions are one thing but cancer, Alzheimer's, Parkinson's, bone loss, hip replacements, limited mobility, limited cognition, limited memory, limited hearing/sight, chronic pain, etc are whole other things.
Intermittent fasting isn't necessarily the same as calorie restriction. It's pretty tolerable if you eat a normal amount of calories, but contained within a 4-6 hour window at night.
I think 'life extension' is not the right way to view it, since living longer is not worth it if you aren't healthy and happy while doing so.
So very, very, very true. And those last years, 80+, let's say, there is the physical state that often has doubtful dignity.. Also the social state, elderly are often isolated and alone and see hopefully their kids once a week, if they're lucky.
I'd personally like to avoid the extreme surgeries (e.g., bypass, joint replacement), the terrible cancers, diabetes, etc. I'm certainly willing to modify my diet and exercise to help avoid such things.
An extra few years, lying in bed, unable to interact w/ the world? Not so interesting.
The desire to translate all nutritional research into diet advice is what leads to fad diets and horrific misunderstanding of what science knows and doesn't know about nutrition and metabolic pathways.
And the desire to continue studying until "we're sure" is what leads to the current obesity epidemic and kids still being taught the ridiculous food pyramid in 2015.
In the mean time I'll probably stick with the Michael Pollan approach to diet - 'Eat food. Not too much. Mostly plants.'