/ck/ - Food & Cooking

How reliable are studies revolving about a healthy diet, regarding what to eat and what to avoid?

I'd like to display it on the example of nuts.
If you observe people that eat nuts or don't eat nuts over the course of several years and check the results, how would you know these outcomes result solely from the consumption/not consuming nuts?

Tell someone he can eat whatever he wants but nuts. He basically ate anything over several years. Any diseases he had or had not had can't possibly be credited to the nuts
Tell someone he should eat nuts everyday. He will eat nuts every day but also other stuff, or he might be physically active, or his results might be altered due to genetic reasons.

Do you understand what I am trying to say? There is so much fuzz about health and food it can drive you crazy if you try to find the right path. Use salt. Don't use salt. Don't use olive oil. Avoid starch. Avoid meat, avoid diary. Canned food is bad. Genetically modified food is bad. Nuts are bad.

Would it be the smartest just to fuck what studies say and just eat what makes you happy? You're going to die anyway and restricting yourself from food just makes the time alive even worse. (this is not a fatty excuse. My main concerns are nuts currently. Reading through some stuff.)