Although energy expenditures increase, food intake usually decreases due to lack of appetite, limited availability of food, and difficulty in food preparation. Even after the symptoms of AMS subside, appetite remains depressed and it takes less food to reach a feeling of fullness - the higher the altitude, the greater the appetite depression. Altitude reduces sense of taste and alters food preferences. These taste changes decrease tolerance to monotonous foods. Individuals often go hungry at high altitude rather than eat food which they do not crave.
Many mountaineers report an aversion to fat and a preference for carbohydrates.
Women may have a biological advantage at altitude. Women, in general, suffer less severe symptoms of AMS and do not experience as great a depression in appetite and food intake as do their male counterparts. Military personnel commonly report lack of time to prepare and consume food and beverages as the reason for limited consumption. Cold ambient temperatures and thin air mean that food starts out colder and heat dissipates faster at altitude. Providing adequate amounts of hot rations is a major challenge for leaders during high altitude operations.