Body composition of high altitude natives on descent to the plains: a densitometric, hydrometric, and anthropometric evaluation.

Body density was experimentally determined at a field location at 3,920 m on 32 medically fit and active high altitude native males using a water displacement technique. Stature, body weight and the bony widths at the elbow, wrist, knee, and ankles; and thickness of skin folds at eight sites were measured. Based on body density and bony widths, body fat, total body water (TBW), mineral mass and total cell solids (TCS) were calculated. Similar measurements were made on another group of 16 high altitude natives after one months stay in Dehli (200 m). TBW of 11 of these subjects was experimentally determined by the oral administration of 200 muCi of tritiated water. This group of subjects was physically less active in Delhi. At high altitude the natives consumed a balanced diet which provided 20.21 MJ, but in the plains the diet provided only 15.69 MJ though it was nutritionally balanced. In spite of the reduced calorie intake this group showed greater fat content in Delhi than the group located at high altitude. These men were also hyperhydrated. Hyperhydration of the lean body could be an adaptive response of the high altitude natives to the new environment. Due to the disturbed state of hydration of the lean body of these men in the plains, use of Siri's formula for the computation of total body fat is questioned.