Dietary macronutrient content and energy intake in the mouse: hedonic or homeostatic override?

OBJECTIVE

The objective of this study was to reconcile how two landmark mouse studies came to opposite conclusions regarding the relationship between dietary macronutrient composition and energy intake. Hu et al. concluded that dietary fat drives excess energy intake because its hedonic properties override energy homeostasis. Solon-Biet et al. concluded that energy intake increases with dietary fat owing to the dilution of protein and carbohydrates, with compensatory feeding for these nutrients dominating inhibitory feedback from fat.

METHODS

Nutritional geometry was used to reanalyze data from Solon-Biet et al. and Hu et al. RESULTS: Results from the two studies are strongly concordant. Neither was designed to measure hedonics but, in both studies, the positive associations among dietary fat, food, and energy intakes are as predicted by compensatory feeding for dietary protein and carbohydrates without the need to impute hedonic effects of fat.

CONCLUSIONS

Whereas conclusions cannot be drawn from either study regarding the role of hedonics, there is evidence for homeostatic feedback operating in both. We suggest that hedonic and homeostatic mechanisms likely interact, with homeostasis being more influential over the longer term. Therefore, "hedonic diversion" may be a more appropriate concept than "hedonic override" when considering energy consumption in mice and, perhaps, humans.