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 composition by electrical impedance. A 29% reduction in energy intake during 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 significant (p = 0.07). As expected, estimated RMR at the end of the expedition--calculated by predictive formulae including body fat and lean body mass as covariates--was significantly reduced by 119 kcal/day as a consequence of the reduction in body weight. Measured RMR values, on the contrary, did not show any significant decline. In conclusion our study showed that high altitude trekking induced a weight loss due approximately 2/3rds to fat mass and 1/3rd to lean body mass. Decreased energy efficiency, which was still present several days after returning to sea level, may have helped contribute to weight loss due to reduced energy intake.

No abstract

Loss of body weight occurs during high mountain expeditions but whether it is due to inadequate diet or other factors is unknown. Moreover the composition of the weight loss is unclear. The aim of our study was to compare the nutritional, anthropometric and metabolic changes during a mountaineering expedition in two groups of climbers, whose dietary energy intake was ad libitum, one given a lacto-fish-ovo-vegetarian diet and one an omnivorous diet. The intake of various nutrients, body weight, body composition and metabolic variables were evaluated before and during high altitude exposure and after the return to low altitude. The two groups were matched for age, body mass index and gender. No significant differences were found for nutritional variables between the two groups. Energy, animal and vegetable protein and fiber intake were significantly lower at climbing quote than before the beginning of the expedition. Significant differences between before the beginning and base camp in all variables were found. Energy and animal protein intake, but not vegetable protein and fiber intake, were significantly lower at climbing quote than at base camp. All subjects significantly reduced body weight, body mass index, waist and hip circumferences but not fat-free mass and fat mass. Metabolic variables significantly improved after the mountaineering expedition. Our study seems to confirm that a mountaineering expedition decreases energy and protein intake, reduces body weight and improves metabolic variables. Because our subjects spontaneously tended to have the same food intake despite the different dietary recommendations, our study failed to observe any differences between the two groups. However, our study shows that a low protein diet, in which the type of protein is mostly vegetable protein, could be adapted for climbers determining only a small decrease of fat-free mass.

Resting metabolic rate (RMR) was evaluated in 27 obese women aged 16-49 y [body mass index (in kg/m2) 27-51] by indirect calorimetry. Visceral and subcutaneous adipose tissue areas, body fat, and fat-free mass (FFM) were measured by a single scan with computed tomography (CT); the waist-hip circumference ratio (W/H) was also used. Comparison between the lowest and the highest RMR quartiles--adjusted for age and FFM--revealed a higher W/H in the highest quartile (0.78 +/- 0.08 vs 0.88 +/- 0.08; P < 0.05). No difference was observed in CT indexes. No differences in W/H were observed after RMR was adjusted for age, FFM, and body fat. Our results point out that RMR, adjusted for FFM and age, correlates with body-fat distribution as evaluated by W/H, but not with visceral fat, as evaluated by CT. Correlations disappeared after RMR was adjusted for body fat as well.

Measurements of regional body fat distribution as determined by waist-to-hip ratio and visceral-to-subcutaneous adipose tissue ratio were compared in 63 obese women. Subjects were divided into three CT-evaluated tertiles on the basis of visceral-to-subcutaneous adipose tissue ratio (group I, 0.05-0.231; group II, 0.232-0.344; group III, 0.345-0.781). The three groups showed no appreciable differences in body weight, body mass index or total abdominal adipose tissue. Waist-to-hip ratio values were significantly lower in group I than in groups II and III. There was no statistically significant difference between groups II and III. Visceral abdominal adipose tissue was significantly and progressively higher in the three groups. Subcutaneous abdominal adipose tissue was significantly lower in group III than in group I. All metabolic variables and systolic and diastolic blood pressure were higher when visceral-to-subcutaneous adipose tissue ratio cut-off values were increased. Waist-to-hip ratio was significantly correlated with total adipose tissue, body mass index, visceral abdominal adipose tissue and subcutaneous abdominal adipose tissue. Visceral-to-subcutaneous adipose tissue ratio was correlated with visceral abdominal adipose tissue (r = 0.84, P < 0.01) and subcutaneous abdominal adipose tissue (r = -0.28, P < 0.05). There was no correlation between visceral-to-subcutaneous adipose tissue ratio and body mass index or total abdominal adipose tissue. Visceral-to-subcutaneous adipose correlated more closely with metabolic variables than did waist-to-hip ratio. Partial correlations between waist-to-hip ratio and visceral-to-subcutaneous adipose tissue ratio and metabolic variables, adjusted for body mass index, showed statistically significant relationships for visceral-to-subcutaneous adipose tissue ratio, but not for waist-to-hip ratio. Visceral-to-subcutaneous adipose tissue ratio correlated with waist-to-hip ratio in the study population as a whole, but only in group I did the correlation between visceral-to-subcutaneous adipose tissue ratio and waist-to-hip ratio prove statistically significant. The present study demonstrates that visceral-to-subcutaneous adipose tissue ratio is a better index of body fat distribution than waist-to-hip ratio.