title: Performance of normal-weight and underweight men with marginal changes in energy intake.
abstract: This study compares the continuous response of six underweight (UW) (body mass index [BMI] < 18 kg/m2) and six normal-weight (NW) (20 < BMI < 25) men of similar age to a modest but sustained level of underfeeding and overfeeding. Habitual energy intake over 4 wk, body composition, and basal metabolic rate (BMR) were measured under metabolic-ward conditions. NW subjects were heavier by 9 kg and had 5% more body fat than UW subjects. The average BMR of UW subjects was 7.5% lower than NW subjects in absolute terms and also per kilogram fat-free mass per day but was higher by 8% when expressed per kilogram body weight per day. Three NW and three UW subjects were given a diet with 10% less energy than their habitual intake for 4 wk. They were brought back to the normal level of feeding for another 4 wk. Finally, they were overfed by 10% for 4 wk. This sequence was reversed in the remaining six subjects. Changes in body weight, BMR, and energy balance were assessed. UW subjects showed a quick and vigorous reduction in BMR (13.4%) during the 1st wk of underfeeding compared with NW subjects (8.1%). In the later weeks, the reduction was 8% in UW and 7% in NW subjects. Furthermore, UW subjects showed a tendency to resist a decrease in body weight (mean loss 180 g), unlike NW subjects (mean loss 730 g). With overfeeding, the mean increase in BMR for UW was higher (7.4%) than for NW (5.3%) subjects.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Biometry and Nutrition, MACS Research Institute, Pune, India.
authors.forename: S A
authors.initials: SA
authors.lastname: Chiplonkar
authors.forename: V V
authors.initials: VV
authors.lastname: Agte
authors.forename: P V
authors.initials: PV
authors.lastname: Sukhatme
mesh_terms: D000273:Adipose Tissue; D000328:Adult; D001481:Basal Metabolism; D001823:Body Composition; D015992:Body Mass Index; D001835:Body Weight; D004032:Diet; D004044:Dietary Proteins / Q000378:metabolism; D004063:Digestion; D002149:Energy Intake; D004734:Energy Metabolism; D006801:Humans; D008297:Male
chemical_list: D004044:Dietary Proteins