Time of Feeding Alters Obesity-Associated Parameters and Gut Bacterial Communities, but Not Fungal Populations, in C57BL/6 Male Mice

Abstract

Fasting and timed feeding strategies normalize obesity parameters even under high-fat dietary intake. Although previous work demonstrated that these dietary strategies reduce adiposity and improve metabolic health, limited work has examined intestinal microbial communities. We determined whether timed feeding modifies the composition of the intestinal microbiome and mycobiome (yeast and fungi). Male C57BL/6 mice were fed a high-fat diet (HF) for 6 wk. Animals were then randomly assigned to the following groups (n = 8–10/group): 1) HF ad libitum; 2) purified high-fiber diet (Daniel Fast, DF); 3) HF–time-restricted feeding (TRF) (6 h); 4) HF–alternate-day fasting (ADF); or 5) HF at 80% total caloric restriction (CR). After 8 wk, obesity and gut parameters were characterized. We also examined changes to the gut microbiome and mycobiome before, during, and following dietary interventions. Body mass gain was reduced with all restricted dietary groups. HF-fed microbiota displayed lower α-diversity along with reduced phylum levels of Bacteroidetes and increased Firmicutes. Animals switched from HF to DF demonstrated a rapid transition in bacterial taxonomic composition, α-, and β-diversity that initially resembled HF, but was distinct after 4 and 8 wk of DF feeding. Time-or calorie-restricted HF-fed groups did not show changes at the phylum level, but α-diversity was increased, with specific genera altered. Six weeks of HF feeding reduced various fungal populations, particularly Alternaria, Aspergillus, Cladosporium, and Talaromyces, and increased Candida, Hanseniaspora, and Kurtzmaniella. However, 8 wk of intervention did not change the fungal populations, with the most abundant genera being Candida, Penicillium, and Hanseniaspora. These data suggest that timed-feeding protocols and diet composition do not significantly affect the gut fungal community, despite inducing measurable shifts in the bacterial population that coincide with improvements in metabolism.