IMR Press / FBL / Volume 19 / Issue 6 / DOI: 10.2741/4261

Frontiers in Bioscience-Landmark (FBL) is published by IMR Press from Volume 26 Issue 5 (2021). Previous articles were published by another publisher on a subscription basis, and they are hosted by IMR Press on imrpress.com as a courtesy and upon agreement with Frontiers in Bioscience.

Open Access Review
Analysis of energy expenditure in diet-induced obese rats
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1 Departments of Animal Science, Texas A&M University, College Station, TX, USA 77843, USA
2 Departments of Statistics, Texas A&M University, College Station, TX, USA 77843, USA
3 Departments of Epidemiology and Biostatistics, Texas A&M University, College Station, TX, USA 77843, USA
4 Departments of Medical Physiology, Texas A&M University, College Station, TX, USA 77843, USA
Academic Editor:Guoyao Wu
Front. Biosci. (Landmark Ed) 2014, 19(6), 967–985; https://doi.org/10.2741/4261
Published: 1 June 2014
(This article belongs to the Special Issue Amino acids in nutrition, health, and disease)
Abstract

Development of obesity in animals is affected by energy intake, dietary composition, and metabolism. Useful models for studying this metabolic problem are SpragueDawley 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.

Keywords
Obesity
Energy Expenditure
Indirect Calorimetry
Statistical Analysis
Review
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