With meal 5 you need a good amount of high GI carbs to replenish muscle glycogen and supress cortisol released during your workout. This would be an ideal time for your potato. In substitute of the spud at meal 2 either brown rice, sweet potato, oats, or barley would be far better. They are all very low GI and rich in nutrients. Your ideas for protein at meal ine are much better. You have to keep in mind that most powders are whey. Whey digests very rapidly and does cause a spike in insulin. When dieting you need to keep insulin as low as possible. Much of whey is also rendered useless because it digests so quickily. In times of caloric deficit, as is the case when you're dieting, it is a PRIME candidate for gluconeogenesis. It will be converted to glucose. I would suggest something like 10 egg whites or siz ounces of some lean meat, but mixing is fine. Just make sure thier high quality protein sources.