Feeding behavior is imperative for the survival and reproduction of animals. Depending on the motivation, feeding is induced by metabolic need or hedonic reason, which is associated with energy demand or pleasurable food intake respectively. Although substantial differences exist, neural circuits for metabolic and hedonic feeding are largely intertwined. Here, we review the distinctions and overlaps between metabolic and hedonic feeding to provide insights into the central regulation of feeding.

Obesity is one of the most severe public health problems and may result in many other related diseases, such as heart disease, diabetes, and stroke. Living habits, particularly excessive caloric intake, are a vital contributor to increasing obesity incidence worldwide. Recent studies have revealed an intimate cross-talk between living habits and the gut microbiome. The gut microbiome has also been identified as a critical player in the cause of obesity. Here we used 16S rDNA amplicon sequencing to investigate changes in the gut microbiome composition of mice fed with a high-fat diet (HFD). The total number of OTUs, Chao index, and Shannon index of the gut microbiome showed an increase in the abundance of specific gut microbiome species. Alternatively, Simpson index indicated a decrease in gut microbiome diversity after HFD feeding. We also found that HFD leads to augments in Firmicutes:Bacteroidetes ratio mainly caused by increased Firmicutes. The total abundance of Bacteroidetes was not changed at the phylum level, while at the family level, both Rikenellaceae and Bacteroidaceae showed a significant increase after the HFD. Additionally, after HFD, we found an increase in the abundance of Proteobacteria related to inflammation and a significant decrease in the proportion of Verrucomicrobia. Our results show that HFD induces a broad gut microbiome change in mice.