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,

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.