Most of the food we eat is quickly broken down in the high-acidity environment of the stomach, then absorbed there and in our small intestines. But fiber survives this entire process and makes its way to the colon unscathed, where it's feasted upon by resident bacteria of the large intestine. Consequently, the more fiber we eat, the more energy we can provide our microbes, and the more abundant and diverse they become. Our microbes then, in turn, do all sorts of good things for us—like help us digest certain foods, regulate our metabolism and blood sugar, and maintain a healthy weight. Research suggests that the healthiest gut microbiome is one full of a diverse flourish of flora, so it follows that high doses of fiber help keep us healthy.