Lentils contain approximately 25% protein, making them a great meat substitute. Lentils are high in fiber, which helps to maintain regular bowel motions and promotes the growth of good bacteria in the stomach. Lentils can help you gain weight in your stool and enhance your overall gut health. Lentils include a wide spectrum of phytochemicals, which are plant components that protect against chronic diseases like heart disease and type 2 diabetes.