Define Food Intake and Energy Requirements for Humans?

Many studies have shown that the subjects loose significant amounts of body mass; fat mass, as well as, fat free mass during a climb to and or a stay at the high altitudes. High altitude-induced weight loss is mainly caused by malnutrition probably due to hypoxia related anorexia, independent of acute mountain sickness. Hypophagia is more pronounced during the first three days of exposure to high altitude even when the best possible food is available. The decreased calories consumption by 40% at 4300 m leads to a negative nitrogen balance.

This, coupled with an increased metabolic rate, induced by high altitude exposure, is considered as a major cause of weight loss.  The taste thresholds for sweet and salt modalities have been found to be elevated while for bitter and sour were reduced. This means we have to add more sugar to our cup of tea to get same sweet taste as at plains. The feeding behaviour is governed by several hormones, endocrine substances and can be modulated by environmental factors. Alterations in appetite regulatory hormones are the current focus of modem research for appetite regulation.