> The Mediterranean diet has been linked to longer lifespans

Did you read anything I wrote? Every single fad diet in the world has multiple scientific papers showing how great it is. (p = 0.05. Nevermind that there were 1000 research projects about this fad diet that didn't get published because they didn't reject the null hypothesis, so who cares. Nevermind that nutrition scientists don't practice good behavior to mitigate the effect of the base rate fallacy on popular subjects.)

Almost no scientific fields practice enough discipline to have very high predictive power. Particle physics mitigates base-rate failures by having an extremely high confidence requirement (5 sigma). Even with absolute best practices, it's sometimes not enough. http://slatestarcodex.com/2014/04/28/the-control-group-is-ou...

Nutrition science is nowhere near best practices.

It's been a while since I've read Michael Pollan's book, An Omnivore's Dilemma, but if I am remembering correctly, there are several locations in the world where people live an abnormally long time, with good quality of life. Researchers went to those places and found out what people usually eat there. Then, comparing the diets of the different qualifying populations, the diet advice Pollan came up with to live a long healthy life was, "eat food, not too much, mostly vegetables."

> there are several locations in the world where people live an abnormally long time, with good quality of life

There are many equally likely explanations that don't involve whatever those people happen to be eating. Regional genetic tendencies, slightly elevated levels of background radiation leading to radiation hormesis, a social tendency towards exercise, etc. It could be all in their diet, but then again, we don't have any really good evidence that it is.

There's a pretty interesting npr program about this. The researcher visits "Blue Zones," areas where people live for abnormally long times, and finds that, if I recall correctly, long lifespans are correlated with strong social support networks, plant-and-fish-based diets, and consistent, low-intensity exercise.

http://www.npr.org/programs/ted-radio-hour/408023272/the-fou...

I think this is the primary criteria, do you care enough about your health to modify your diet even if the health benefits might be minute or null?

If you do, then some diets have better odds, like the Mediterranean diet.

It seems to me you don't care enough, or believe a random diet or one selected by the food industry will give you better odds.

Sure, diets are not miracle life extenders or cure for disease. At least none of the known diets have been able to confidently show they are. But a diet is not like sending someone to the moon where you need very close to 100% confidence in your technique. A diet just needs to beat the odds of your current diet. In that sense, most diets, even fad ones, probably beats the average American diet odds.