The effect of overfeeding and variations in body composition on resting metabolism and work performance has been examined in the adult dog. At rest, the mean O2 uptake was 85.5 cc/min. and the R.Q. was .65. These were not substantially altered by 20% gain in weight associated with variations of 12%–20% in body fat content. Work performance was tested during a 50-min. period of treadmill running at a fixed work intensity of 202.9 kg-m/min. Oxygen uptake, work and recovery pulse rates were constant. However, the respiratory quotient increased from .81 to .95 and water loss during work increased from 1.16 cc/Cal. to 1.84 cc/Cal. with gain in weight and adiposity. It is concluded that the most important effect of gain in weight is to promote increased water loss during constant steady-state work.
Submitted on December 11, 1959
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