Fruits and vegetables. Your mom told you they were good for you. She was right. Whole grain breads, and pastas are perfectly acceptable. Eat these foods with a protein and their glycemic index is actually lowered.
Red meat is a source of much debate.
Basically, I say if you're dieting stay away from it. Even if you're not dieting, you should only eat it on rare occasions. Having a lean 8 oz steak every couple of weeks isn't going to hurt you. The obviously better choices are turkey, chicken, and fish. Fish, is an excellent source of protein, vitamins, minerals, and healthy oils.