Increase in weight and water retention on overfeeding dogs

Dogs, kept in metabolism cages, were weighed daily and the daily water intake, urine volume and evaporative loss of water measured or calculated. When the daily meal was doubled, the weight increased in two phases: during the first 4 d the increase in weight was more than could be accounted for by the deposition of protein, glycogen and fat so that water retention must have occurred; after the fourth day the increase in weight was slower and could have been due to the deposition of solids, without water retention. When carbohydrate was added to the meal either as starch or glucose, the increase in weight in the first 3 d was more than the weight of the added carbohydrate, showing water retention. After the third day the slower increase in weight could be explained by the deposition of solids. When the daily meal was supplemented with fat, increase in weight occurred uniformly throughout the period of overfeeding and was equal to or less than the added fat. There was thus no evidence for water retention. Addition of meat to the daily meal caused an increase in weight larger than the fat and protein of the extra meat. Meat therefore caused water retention. The results indicate that during overfeeding, deposition in the body of protein and glycogen, but not fat, determines water retention.