Abstract:Obesity related metabolic diseases seriously affect human health all over the world. It's found that the disorder of gut microbiota leads to the increase of conditional pathogenic bacteria and harmful bacterial metabolites, which is involved in the occurrence and development of obesity related metabolic diseases. Diet is one of the important factors affecting gut microbiota. Caloric restriction as one of dietary intervention, a lot of evidence have proven that it can significantly improve the symptoms of metabolic diseases such as obesity, diabetes and nonalcoholic fatty liver disease. Gut microbiota may be one of its targets. Therefore, this paper reviews from such following three aspects as the changes of gut microbiota in obesity, diabetes and nonalcoholic fatty liver disease, the therapeutic effect of caloric restriction on these three metabolic diseases and the mediating role of gut microbiota in the process.