Water is like fat-burning fuel: It’s what your metabolism requires to function optimally, especially in the summer heat when we tend to lose water faster than normal. In fact, numerous studies have linked proper hydration — between half an ounce and an ounce of water for each pound you weigh — to improved weight loss. In fact, one study in The Journal of Clinical Endocrinology and Metabolism found drinking water (17 ounces) could increase fat-burning by 30 percent. Dehydration, on the other hand, slows calorie-burning. Make a summertime fetish of toting around a water bottle. Throw in a sliced lemon for good measure. Limonene, a compound found in the peel, is a great natural detoxifier, as it helps the liver to flush excess toxins from the system.