Fig. 1
From: It's the fiber, not the fat: significant effects of dietary challenge on the gut microbiome
Lack of soluble fiber and increased fat in diet formulations influence weight gain in mice in an age- and sex-specific manner. a Schematic of the experimental study design. Young adult (17 weeks old) and 1-year aged (60 weeks old) C57Bl/6:I129 males and females consuming a chow diet were switched to a refined low-fat diet (rLFD) for 1 week to acclimate. Following acclimation to a refined diet, half of the animals remained on rLFD while the other half was switched onto a 45% refined high-fat diet (rHFD). Purple circles denote times when fecal samples were collected. Animals were co-housed and therefore all analysis is conducted at the level of the cage to control for co-housing effects (N = 3 cages/age/sex/diet, total N = 92 mice). b Composition of diet nutritional composition and ingredients for the chow, rLFD, and rHFD, demonstrating differences in fiber source and quantity between chow and refined diets. c–f To determine the impact of dietary switching in young adult and aged males and females, weekly body weights were collected prior to refined diet switch, 1 week following switch to rLFD, and weekly measurements during consumption rLFD or rHFD. c Body weight was significantly changed over time in young adult females (RM ANOVA, main effect of time, F5, 110 = 15.39, P < 0.000, main effect of diet, F1, 22 = 2.920, P = 0.1016, N = 24, time × diet interaction, F5, 110 = 2.782, P = 0.021). d Body weight of aged females was significantly changed over time (RM ANOVA, main effect of time, F5, 90 = 17.43, P < 0.0001, N = 20), across diets (RM ANOVA, main effect of diet, F1, 18 = 6.800, P = 0.0178, N = 20), and their interaction (RM ANOVA, time × diet, F5, 90 = 12.02, P = < 0.0001, N = 20). Post hoc analysis revealed aged females fed rHFD weighed more at 2 (t108 = 3.499, P = 0.0041), 3 (t108 = 3.748, P = 0.0017), and 4 (t108 = 4.781, P < 0.0001) weeks compared with rLFD-fed aged females. e Body weight was significantly changed over time in young adult males (RM ANOVA, main effect of time, F5, 105 = 88.146, P < 0.0001, main effect of diet, F1, 21 = 0.4240, P = 0.522, N = 23). f Body weight of aged males was significantly changed over time (RM ANOVA, main effect of time, F5, 100 = 67.034, P < 0.0001, N = 22). Data represented as mean ± SEM. Repeated measures ANOVA followed by Sidak correction for multiple comparisons. *P < 0.05, **P < 0.01, ***P < 0.001