I seem to gain weight when I eat wheat. When I eliminate wheat, my weight is stable.

I found a study about how wheat interferes with leptin (the hormone that makes us feel full): http://www.biochemj.org/content/410/3/595

I think I've read several places that the wheat we eat today is significantly different from the wheat people ate in the old days. If I remember correctly, our wheat contains much more gluten, since high-gluten wheat makes bread fluffier etc.