Water is essential for your body. It prevents dehydration, constipation, and kidney stones. Plus, with no calories, it’s the best beverage for your waistline. If you add 1 to 3 cups of water a day to your diet, you could end up taking in less fat, salt, sugar, and up to 200 fewer calories per day. Too plain? Calorie-free flavor drops sweeten, but may have artificial flavors, colors, or preservatives. Try a squeeze of citrus instead.