Diet is a subject that everyone is interested in, but no one really knows about. I keep seeing questions like "will X cause me to gain or lose weight" and answers like "no, it's calories in calories out". Followed by the response "it's more complicated than that". The truth is that science does not know yet. There is no clinically validated diet that has shown significant long term weight loss. Answers are based on anecdotes and what people believe from what they have heard, or what "makes sense" to them, usually without any scientific backing. The very best answers are based on hypotheses that still require validation in the clinic. Voting is done for the same reason.
The point of stackexchange is to provide a location where people can go for expert opinion, to get real, accurate information. I don't think the field of nutrition is up to the task yet. The quality and accuracy of the answers regarding diet just don't hold up to the standards of the other stackexchange forums because the unambiguous information does not exist. I propose that weight-loss and weight-gain related questions be disallowed.