THE EFFECTS OF HIGH-ALTITUDE TREKKING ON BODY-COMPOSITION AND RESTINGMETABOLIC-RATE

Resting metabolic rate (RMR) and body composition were evaluated in 12 healthy volunteers before and after 16 days of high altitude trekking and climbing. RMR was measured by indirect calorimetry and body compo sition by electrical impedance, A 29% reduction in energy intake durin g high altitude exposure was observed. Fat mass loss averaged about 2. 2 kg (p<0.05) and lean body mass about 1.1 kg, which was almost signif icant (p=0.07). As expected, estimated RMR at the end of the expeditio n - calculated by predictive formulae including body fat and lean body mass as covariates - was significantly reduced by 119 kcal/day as a c onsequence of the reduction in body weight, Measured RMR values, on th e contrary, did not show any significant decline, In conclusion our st udy showed that high altitude trekking induced a weight loss due appro ximately 2/3 rds to fat mass and 1/3 rd to lean body mass. Decreased e nergy efficiency, which was still present several days after returning to sea level, may have helped contribute to weight loss due to reduce d energy intake.