Good bacteria in the gut comes about from a healthy high fibre diet, avoiding sugars and eating more prebiotic and probiotic foods. Intestinal flora plays an important role in the appropriate development of the metabolic system in humans. Disturbances in the composition and functionality of the intestinal flora can disrupt gut barrier function, causing low-grade chronic inflammation of the body due to a leakage of inflammatory bacterial fragments into the circulation, contributing to weight gain and insulin resistance. Improving to a high fibre diet and taking probiotic supplements may help restore normal gut flora.
Gut microbiota, obesity and diabetes. Postgrad Med J. 2016 May;92(1087):286-300. doi: 10.1136/postgradmedj-2015-133285. Epub 2016 Feb 24. https://www.ncbi.nlm.nih.gov/pubmed/?term=Gut+microbiota%2C+obesity+and+diabetes.+Postgrad+Med+J.+2016%3B+92(1087)%3A286-300