Altitude acclimatization and altitude exercise are physiologically demanding for the body. During exercise at high altitudes, energy and fluid needs are almost difficult to satisfy with normal food intake. An inappropriate thirst and appetite response can contribute to rapid dehydration, glycogen depletion and weight loss unless adequate amounts of food and fluid are ingested. Dehydration may intensify the symptoms of altitude sickness and result in an even lower food intake. The first and the most effective preventative measure is to consume a minimum of 3 to 5 liters of fluid per day containing 200 to 300 mg of carbohydrate, in addition to that contained in the diet. In order to improve energy, protein and micronutrient (especially antioxidants and iron) intake, nutrient rich nutritional supplements may be used, which may suffice for short periods of strenuous exercise (e. g. heavy climbing), when normal food intake is almost impossible. These measures can help prevent dehydration, improve energy balance and the oxygen supply capacity of the circulatory system, replenish muscle glycogen and conserve bodily protein.