THE EFFECTS OF DIURETICS ON RESTING METABOLIC RATE AND SUBSEQUENT SHIFTS IN RESPIRATORY EXCHANGE RATIOS

Abstract

The purpose of this research was to determine the effect of diuretic-induced dehydration on resting metabolic rate (RMR) and respiratory exchange ratio (RER). It was hypothesized, based on a prior pilot study, that a loss of 3–5% body water would reduce RMR. Fourteen nonobese, apparently healthy, female volunteers were recruited to participate in the study (body fat 17.19 ± 1.65%, body weight 58.25 ± 5.93 kg, age 25.21 ± 3.36 yr). The study utilized a within subjects repeated measures design where each participant underwent a diuretic (D) treatment and a control (C) treatment. Participants spent two consecutive nights in the Human Performance Research Laboratory. Under the diuretic treatment, participants received a 1mg/kg dose of furosemide upon arrival the first night. Participants were fed a control diet and lights were turned out at 10:30pm both nights. RMR and RER were measured in a waking state between 5:45–6:30 am both mornings. Percent dehydration in D ranged from 1.77–4.39% with a mean of 3.09%. The average urine outputs and hematocrits were significantly higher for D (2677 ± 700ml, 45 ± .02%) than for C (1519 ± 723ml, 42 ± .02%). There were no significant differences in urine specific gravities for D and C. Mean energy expenditure (MEE) was significantly lower (p < 0.05, one-tailed) in D (1253 ± 145 kcals/day) than in C (1304 ± 130 kcals/day). RER was significantly higher (p < 0.05, one-tailed) in D (.98 ± .06) than in C (.94 ± .08). Diuretic use to promote weight loss could result in a lower RMR and diminshed fat metabolism.