Why can some people eat as much as they want and still not gain weight? Others only have to look at a piece of chocolate, and it ends up on their hips. The decision is made in the gut. Countless gut bacteria are responsible for how well or poorly we process our food. The bad news: Those with the wrong bacteria in their gut will gain weight more quickly despite a healthy diet. The good news: We can influence which bacteria dominate in our gut. With over 100 gut-friendly recipes!.