title: Metabolizable energy intake during long-term calorie restriction in rhesus monkeys.
abstract: Calorie restriction (CR) is a dietary intervention shown to increase maximum life-span. The aim of this study was to compare the metabolizable energy of the pelleted semi-purified diet with estimated energy intake from food weight. Energy density of diet, urine and feces were measured by bomb calorimetry in rhesus monkeys (23-29 years old) on CR (CR, n=11) and control (C, n=9). Food moisture was measured to be 2-fold higher (9+/-1%) than indicated on the label (approximately 5%). The measured gross energy of diet was 4.4 kcal/g dry weight of CR and 4.5 kcal/g dry weight of C diets. In a two-day trial, food intake (mean+/-SD) was 112+/-20 g and 136+/-26 g of dry mass/d in the CR and C monkeys, respectively (p=0.003). The fraction of the diet absorbed (CR=0.91; C=0.95) was different (p<0.001) between CR and C monkeys. Using these coefficients, the metabolizable energy intake averaged over 6 months was 450+/-53 and 534+/-97 kcal/d in CR and C monkeys, respectively (Diff=16%; p=0.03). These values were compared with energy expenditure (EE), as measured annually by indirect calorimetry (490+/-61 kcal/d in CR and 532+/-62 kcal/d in C monkeys). Adjusted for changes in body composition (2+/-10 kcal/d in CR and -7+/-12 kcal/d in C), energy balance was not different from zero in CR (-42+/-42 kcal/d) and C (9+/-61 kcal/d) monkeys. Use of diet weight is a reasonable estimate of the level of CR when food waste is assessed.
authors.affiliation: Department of Nutritional Sciences, University of Wisconsin, Madison, WI 53706, USA.
authors.forename: Aarthi
authors.initials: A
authors.lastname: Raman
authors.forename: Scott T
authors.initials: ST
authors.lastname: Baum
authors.forename: Ricki J
authors.initials: RJ
authors.lastname: Colman
authors.forename: Joseph W
authors.initials: JW
authors.lastname: Kemnitz
authors.forename: Richard
authors.initials: R
authors.lastname: Weindruch
authors.forename: Dale A
authors.initials: DA
authors.lastname: Schoeller
mesh_terms: D000818:Animals; D001823:Body Composition / Q000502:physiology; D031204:Caloric Restriction; D002153:Calorimetry, Indirect / Q000379:methods; D004063:Digestion / Q000502:physiology; D004435:Eating / Q000502:physiology; D002149:Energy Intake / Q000502:physiology*; D004734:Energy Metabolism / Q000502:physiology; D005243:Feces; D008253:Macaca mulatta / Q000502:physiology*; D008297:Male; D011659:Pulmonary Gas Exchange / Q000502:physiology; D014556:Urine / Q000502:physiology