Water Exchange in Men on a Restricted Water Intake and a Low Calorie Carbohydrate Diet Accompanied by Physical Work

¹ From the Laboratory of Physiological Hygiene, University of Minnesota, Minneapolis, Minnesota

After 21 days of control 12 soldiers subsisted for 16 days on 1000 Cal. from carbohydrate, 4.5 gm NaCl and one multivitamin tablet per day. Six of the men received 900 ml of water daily during the first 5 days of food restriction, the other six were allowed 1800 ml per day during the first 10 days. Water ad libitum was given for the rest of the experiment. Physical work equivalent to about 1200 Cal. per day was performed regularly throughout. The men ate, worked and slept in an air-conditioned suite at 78°F and 40–45% relative humidity. Average weight loss at the end of 5 days of food and water restriction was 6.41 kg (8.5%) for the men receiving 900 ml H₂O, and 4.37 kg (6.0%) for those receiving 1800 ml. Water balance was –5.0 kg and –3.0 kg, respectively. Another 13 men under similar conditions but receiving water ad libitum had an average weight loss of 3.1 kg (4.5%) and a water balance of –1.8 kg. Through decrease of output, water equilibrium was attained by the men on 1800 ml water on and after the 6th day of combined food and water restriction. Both water restricted groups showed marked decreases of sweating during work and of insensible work loss during sleep. When water was given ad libitum sweat and insensible loss rose and when the normal diet was reinstituted they rose still further.