Why is it obvious? These are the exact questions that nutritionists are trying to answer without the benefit of being able to force people to eat what they want to test because they're in a Nazi death camp.

Do you know, for example, that poor Japanese in the navy used to just eat rice. Nothing else. Just plain rice:

https://medium.com/war-is-boring/eating-too-much-rice-almost...

Some had to be forced to eat protein by chopping it up into the rice.

Or that someone did a twinkie diet and it worked:

http://edition.cnn.com/2010/HEALTH/11/08/twinkie.diet.profes...