I think it is a case by case basis-similar to what Mrs. D mentions above.

Each person needs to find their niche. I can't do strictly vegetarian-I've tried several times, and I just get weak and unwell from it (and I was eating very healthfully with plenty of protein sources).

I also don't do well with lots of meat or lots of cheese.

For me, pescetarian (sp?) is the right way to go. I do eat grains-but in smaller amounts, and usually things like steal cut oats and on occasion brown rice. Beans are fine for me, and I enjoy them a lot.

When I try to go totally grain free, my guts act up, and I get IBS type symptoms. Usually a bit of steal cut oatmeal at the start of my day is enough to make this not the case.