Body Composition Changes Resulting from Fluid Ingestion and Dehydration

Abstract

Abstract In order to ascertain the effects of altered state of hydration on body composition measurements, ten subjects were compared before and after water ingestion and dehydration. As a result of an average ingestion of 1.81 liters of water, body weight increased by 1.77 kg (2.4%). Since underwater weight and residual lung volume were essentially unchanged, the calculation of body fat increased 1%. A week later the subjects were placed in a sauna for 35 min at a temperature of approximately 170° F. Average weight loss due to sweating was .98 kg, which resulted in a calculated .7% decrease in body fat. The changes in body weight, density, and percent fat in both conditions were statistically significant (p < .01). It was found that the resultant error in body fat calculation from the hyperhydrated to the dehydrated state could amount to 20% (2% in actual body fat). It is recommended that when obtaining measures of body density by hydrostatic weighing the subject's normal level of hydration be ascertained.