In America, obesity is an epidemic with 36% of American adults currently obese and 70% overweight. Obesity is mainly due to certain dieting habits found in the western diet, such as high-calorie foods, overconsumption of carbs and saturated fats. However, animal studies have shown that diet alone is not enough to induce obesity. So what could be a root cause of the obesity epidemic?

The gut microbiome may explain the rising rates of obesity. Because the intestinal microbiome assists in the digestion of polysaccharides, this can increase the amount of glucose being sent to the liver, ultimately leading to lipogenesis. The typical microbiota of an obese human has been discovered. There is an increased ratio of Firmicutes to Bacteroidetes (both are types of intestinal bacteria), that can be associated with metabolic syndrome. Genetically obese mice have 50% fewer Bacteroidetes and more Firmicutes than lean animals. The microbiota of an obese animal assist in digestion, releasing more calories during digestion than that of lean animals.

PASSOS, Maria do Carmo Friche, & MORAES-FILHO, Joaquim Prado. (2017). INTESTINAL MICROBIOTA IN DIGESTIVE DISEASES. Arquivos de Gastroenterologia, Epub July 06, 2017.