Avoid fatty foods such as potato chips, donuts and fried foods. These foods do little to maintain blood sugar levels. The fat leaves the stomach very slowly and can leave you feeling bloated during exercising. Your body can convert both protein and starch to fat if not enough fat is available in the diet. Avoid high protein foods such as nuts, the more protein dense legumes, and of course meats of any kind.
Protein is the toughest nutrient to digest.
Excessive protein tends to increase urine output, which can lead to excessive fluid and mineral loss. Animal protein byproducts can rob the body of valuable minerals such as calcium, creating a mineral imbalance leading to cramping. Limit high fibre foods, i.e. bran muffins, added bran cereals and breads, and fibrous raw vegetables, especially prior to events longer than two hours. During the event or exercise Generally, if the exercise or event you are in takes 90 minutes to 2 hours you'll probably only need to replace spent body fluids. Don't wait till your thirsty, it takes 15-20 mins for your body to utilize the water you just drank.