High-fat diet action on adiposity, inflammation, and insulin sensitivity depends on the control low-fat diet

Abstract

Animal studies using a high-fat diet (HFD) have studied the effects of lipid overconsumption by comparing a defined HFD either with a natural-ingredient chow diet or with a defined low-fat diet (LFD), despite the dramatic differences between these control diets. We hypothesized that these differences in the control diet could modify the conclusions regarding the effects that an increase of fat in the diet has on several metabolic parameters. For 11 weeks, C57bl6/J mice were fed a low-fat chow diet (8% energy from fat), a typical semisynthetic LFD (12%), or a semisynthetic HFD (sy-HF) (40%). Conclusions about the effect of sy-HF on body weight gain, subcutaneous adipose tissue, insulin sensitivity, and adipose tissue inflammation were modified according to the control LFD. Conversely, conclusions about epididymal and retroperitoneal adipose tissue; fat intake effects on liver and muscular lipids, cholesterol, free fatty acids, and markers of low-grade inflammation; and of adipose tissue macrophage infiltration were the same regardless of the use of low-fat chow diet or semisynthetic LFD. For some physiological outcomes, conflicting conclusions were even reached about the effects of increased fat intake according to the chosen low-fat control. Some deleterious effects of sy-HF may not be explained by lipid overconsumption but rather by the overall quality of ingredients in a semisynthetic diet. According to the control LFD chosen, conclusions on the lipid-related effects of HFDs must be formulated with great care because some end points are profoundly affected by the ingredient composition of the diet rather than by fat content.

Keywords: AUC; Adipose tissue; BAT; CD11c; CD68; HFD; High fat diet; IL-6; Inflammation; Insulin sensitivity; LFD; MCP1; Mice; TG; WAT; area under the curve; brown adipose tissue; ch-LFD; chow LFD; cluster of differentiation 11c; cluster of differentiation 68; eWAT; epididymal white adipose tissue; high-fat diet; interleukin 6; low-fat diet; mRNA; messenger RNA; monocyte chemoattractant protein 1; pAKT; phosphorylated AKT; rWAT; retroperitoneal white adipose tissue; scWAT; semisynthetic high-fat diet; semisynthetic low-fat diet; subcutaneous white adipose tissue; sy-HFD; sy-LFD; triglycerides; white adipose tissue.