Heat exchanges of men during caloric restriction in the cold

¹ Environmental Protection Research Division, Quartermaster Research and Engineering Command, U. S. Army, Quartermaster Research and Engineering Center, Natick, Massachusetts

The ability of men to maintain thermal balance during continuous cold exposure (14 days at 15.6 C, sedentary while nude) was assessed under four regimens of caloric intake: a) adequate, 2,800 kcal/day; b) moderate restriction, i.e., sufficient to maintain weight in a warm environment but without the added calories to support shivering, 2,600 kcal/day; c) marked restriction, 600 kcal/day; and d) complete starvation, 0 kcal/day. Respective weight losses for b, c, and d were 1.8, 8.2, and 12.2% body wt. With 600 and 0 kcal/day there was an impaired ability to maintain rectal temperature; under these conditions the men exhibited rectal temperatures 0.7 C lower than when they were on adequate or nearly adequate caloric intake. The men on complete starvation had the lowest heat production of all groups during later days in the cold; however, the data were too variable to demonstrate a close relationship between depressed core temperature and decreased heat production. It is concluded that marked restriction of calories is associated with depressed core temperatures during prolonged cold exposure, due in part to absence of specific dynamic action.

Note:
(With the Technical Assistance of Edward B. Green and John A. Vaughan)