Pineapple juice contains an enzyme called bromelain. This enzyme is found in the juice of pineapple and helps in metabolising protein, which in turn helps burn away the excess belly fat. Mangos are a good source of protective compounds with antioxidant properties, these plant chemicals include gallotannins and mangiferin. Both have been studied for their ability to counter the oxidative stress associated with day to day living and exposure to toxins. Passion fruit is full of this antioxidant. Your body uses it to make blood vessels, cartilage, muscles, and collagen, which keeps skin looking young.