4. Blackberry-sage water. Blackberries are delicious, low-calorie berries that are well-packed with vitamins, anti-oxidants and minerals. Sage is also a low-calorie plant that is a great source for anti-oxidants. It prevents damage of body cells and improves the immune system. Take 4-5 fresh sage leaves, mix them with 1cup blackberries (mash them slightly) and 10 cups of water. Stir the ingredients and leave your drink overnight in the fridge.