MICROBIOME NEWS: Bacteria Inside You May Explain Why Weight Piles on After Dieting. “In trials involving mice being put through 10 different dieting protocols, species of Lactobacillus and their metabolites were shown to increase in the guts of the animals once their fasting ended and they were reintroduced to a less restricted diet. That microbiome change, the researchers discovered, assisted the intestinal tissues in absorbing more fat. It’s likely that the same process happens in the guts of humans, and periods of intermittent fasting or controlling calorie intake encourages the gut to increase its ability to extract fat from our diet, making it more likely for weight to be regained.”