title: Analysis of energy expenditure in diet-induced obese rats.
abstract: Development of obesity in animals is affected by energy intake, dietary composition, and metabolism. Useful models for studying this metabolic problem are Sprague-Dawley rats fed low-fat (LF) or high-fat (HF) diets beginning at 28 days of age. Through experimental design, their dietary intakes of energy, protein, vitamins, and minerals per kg body weight (BW) do not differ in order to eliminate confounding factors in data interpretation. The 24-h energy expenditure of rats is measured using indirect calorimetry. A regression model is constructed to accurately predict BW gain based on diet, initial BW gain, and the principal component scores of respiratory quotient and heat production. Time-course data on metabolism (including energy expenditure) are analyzed using a mixed effect model that fits both fixed and random effects. Cluster analysis is employed to classify rats as normal-weight or obese. HF-fed rats are heavier than LF-fed rats, but rates of their heat production per kg non-fat mass do not differ. We conclude that metabolic conversion of dietary lipids into body fat primarily contributes to obesity in HF-fed rats.
authors.affiliation: Department of Animal Science, College Station, TX, USA 77843-2471.
authors.forename: Houssein
authors.initials: H
authors.lastname: Assaad
authors.affiliation: Department of Animal Science, College Station, TX, USA 77843-2471.
authors.forename: Kang
authors.initials: K
authors.lastname: Yao
authors.affiliation: Department of Animal Science, College Station, TX, USA 77843-2471.
authors.forename: Carmen D
authors.initials: CD
authors.lastname: Tekwe
authors.affiliation: Department of Animal Science, College Station, TX, USA 77843-2471.
authors.forename: Shuo
authors.initials: S
authors.lastname: Feng
authors.affiliation: Department of Animal Science, College Station, TX, USA 77843-2471.
authors.forename: Fuller W
authors.initials: FW
authors.lastname: Bazer
authors.affiliation: Department of Animal Science, College Station, TX, USA 77843-2471.
authors.forename: Lan
authors.initials: L
authors.lastname: Zhou
authors.affiliation: Department of Animal Science, College Station, TX, USA 77843-2471.
authors.forename: Raymond J
authors.initials: RJ
authors.lastname: Carroll
authors.affiliation: Department of Animal Science, College Station, TX, USA 77843-2471.
authors.forename: Cynthia J
authors.initials: CJ
authors.lastname: Meininger
authors.affiliation: Department of Animal Science, College Station, TX, USA 77843-2471.
authors.forename: Guoyao
authors.initials: G
authors.lastname: Wu
mesh_terms: D000818:Animals; D001835:Body Weight / Q000502:physiology; D059305:Diet, High-Fat / Q000009:adverse effects*; D004734:Energy Metabolism / Q000502:physiology*; D005260:Female; D008297:Male; D009765:Obesity / Q000209:etiology / Q000503:physiopathology*; D010101:Oxygen Consumption / Q000502:physiology*; D017207:Rats, Sprague-Dawley; D017208:Rats, Wistar