I think it’s the same for most people, regardless of age. Charliecompany has mentioned several things, and I agree in particular with the HFCS. It’s tough to get rid of completely but you can remove a good deal of it from your diet. READING LABELS is a big part of this. Try to not eat HFCS, aspartame, Splenda (sucralose) or any artificial sweetener. Also try to avoid any partially hydrogenated oils.
Aim for lots and lots of vegetables, but don’t overcook them.
Whole grains as opposed “fortified enriched” white flour type of breads. Eat complex carbohydrates more than simple carbs. (Example: sweet potato instead of white bread.)
Fruits are great, but I try to eat them (and any simple carbs) early in the day and stick with higher protein in the evening. It seems to be helping me to lose weight in my abdominal region.
Protein is important for rebuilding muscle tissue. Lowfat protein is better for you because it doesn’t contain as much saturated fat. Typically, chicken, turkey and fish fall in this category. Red meat is not the devil, just get a lowfat cut. (Although I will say that I like a turkey burger almost as much as I like beef or venison burger.)
And don’t even get me started on exercise!