A high-protein diet can also make you feel more full and reduce your appetite. In fact, some studies show that people eat over 400 fewer calories per day on a high-protein diet . Not surprisingly, those eating the very low carbohydrate version of the diet went into ketosis. Not surprisingly, given their reports of less hunger and cravings, they also spontaneously ate less food and lost more weight.
Short of this sort of hard reset of the microbiome, preliminary research has shown that adding even a single bacterial species to a person’s gut can alter her metabolism. The relationship between microbes and weight gain has long been overlooked in humans, but people have known about similar effects in animals for decades. After World War II, antibiotics became affordable and abundant for the first time.