Carbohydrate versus fat intake: differing patterns of macronutrient selection in two inbred mouse strains.

Abstract

As a first step toward developing a mouse model to characterize genetic factors linked to the preferential intake of dietary carbohydrate or fat, we have identified two mouse strains that exhibit distinctly different patterns of macronutrient selection. Macronutrient selection was evaluated in AKR/J and SWR/J mice, two strains that have been characterized previously for their sensitivity to high-fat dietary obesity. Mice were adapted to a self-selection protocol in which separate carbohydrate, fat, and protein sources were simultaneously available. AKR/J mice ate 30% more calories than the SWR/J mice. Furthermore, strain comparisons revealed a significantly higher proportion of fat intake by the AKR/J mice (69 vs. 28%), and in the SWR/J mice a significantly higher intake of carbohydrate (62 vs. 24%). The mice were then returned to a standard chow diet for 10 wk. These mice subsequently were allowed to self-select from two composite energy diets (carbohydrate and protein, or fat and protein). Once again, AKR/J mice selected a greater proportion of energy from the fat/protein diet (85%) than did the SWR/J strain (32%). These findings suggest a possible relationship between sensitivity to dietary obesity and fat selection.