A probiotic that can help you stay fit? It’s true! Lactobacillus Gasseri is a unique species of probiotic with activity that sets it apart from all other strains. The lactic acid-producing bacterium supports GI tract function by adding valuable protection for the stomach lining and mucosa of the intestinal tract. In addition, several strains of Lactobacillus Gasseri have been shown to have an effect on leptin, a hormone that plays a pivotal role in energy metabolism and fat storage.