As a Cooking moderator, I've seen my fair share of "healthy eating" questions. We always close them with the hammer, because they make the worst kind of question: nobody has the required knowledge (not even the best world specialists on them), but everybody has an opinion. And everybody takes them personally too.
An example of a question which is merely unanswerable would be "What is healthier, sugar or honey?". What does it mean, "healthier"? Nobody can enumerate all effects one or the other has on the body. OK, so somebody could probably point to the one or other animal model obesity study, but most people don't know that the results are seldom transferrable to humans with a normal life, as opposed to Black six mice fed their body weight in honey.
But the larger problem is that for this question, I can promise you that you will get at least one low-carb person calling damnation on you if you eat either of them, in any amount, one person telling you that sugar is clearly evil because it's not natural (their definition of "natural" seems to mean "man-made by a method known in the 17th century), and probably a paleo guy saying that sugar is a no-no, but honey would be OK if you harvested it yourself. And then somebody will point out that artificial sweeteners are superior to both because they are obviously zero calories, only to be torn to pieces by the "natural" answerer.
Whatever you decide, it is probable that your community will face trouble with nutrition questions. Assuming that they are allowed, you have to somehow manage to avoid two possible situations:
- Everything goes. All the dupes get to have long shouting matches whether gluten from spelt is more natural than gluten from wheat.
- The theories popular among the high-rep users are considered canonical and are allowed, and everything which contradicts them is removed swiftly.
As a further help, I posted five question proposals which have been asked verbatim on Cooking by different users (they are closed there). I'm interested to see how they will be seen among the community here.
Here also an example of a typical post of a health-conscious user, reproduced verbatim (it was posted as an answer on https://cooking.stackexchange.com/questions/28747/is-there-a-definitive-way-to-know-if-a-tin-can-is-lined-with-bpa/):
I have heard [BPA] is banned from all products sold in the European Union. Apparently they are waaaay ahead of us on some common sense type problems. I'v also heard red40 and blue six, yellow 5 and many others have been proven to cause cancer yet they are still in EVERYTHING in the U S. I find this vexing. I'm terribly vexxed. I wouldnt give these products to prison inmates or wild animals let alone our own children , yet go grab a little debbie snack these days or some croutons and youre likely to be enjoying some red40 or some MonosodiumGlutamate(MSG for the uninitiated which causes skizophrinia as well as siezures in rare cases)mmmmm yum yum yum :P
I deleted it today using the simple reason: it's about health, so off topic for us. It won't work for your community, so you'll need rules about dealing with such content which are 1) not open to personal abuse by whoever enforces them, and 2) still permissive enough that good content can be posted.