The benefits of altitude training probably last for 4-6 weeks after return to sea level. Nutritional Requirements at Altitude Barry Braun, PhD Barry researches fuel metabolism at high altitude. He is currently assistant professor in the Department of Exercise Science, University of Massachusetts, Amherst. The extra stress of altitude leaves less room for error in nutrition and other lifestyle factors. Athletes need to be more vigilant with their intake of nutrients.
Iron deficiency can also reduce the benefit of altitude exposure, particularly in female athletes.
Hypoxia leads to appetite suppression. Athletes tend to eat smaller meals, for a typical reduction in caloric intake of about 200 to 300 kcal per day. Basal metabolic rate increases at altitude, especially during the first few days. Depending on the altitude and the athlete's individual metabolism, the increase may be 100 to 200 kcal per day. The result of decreased energy intake and increased basal metabolic rate is gradual reduction in body weight.