Probiotics, friendly bacteria like those found in yogurt and pickles, may be the key to losing those last stubborn inches around your waist. They not only help the digestive system work properly, but also have a profound effect on the metabolism, according to a new study in Molecular Systems Biology. The bacteria Lactobacillus paracasei and Lactobacillus rhamnosus can change how much fat is available for the body to absorb by influencing stomach acids during digestion. The best sources of live bacteria are yogurt, acidophilus milk, miso soup, soft cheeses, pickles, and sauerkraut.