Lemon juice boosts metabolism, which is why it's recommended that you drink lemon water first thing in the morning. Lemon juice has an acidic composition that can help the body rid itself of toxins and undesirable elements. It also encourages the liver to produce bile, which helps with digestion and detoxification. Lemon juice hydrates you while simultaneously promoting satiety and lowering your calorie consumption. Lemon water is believed to have only six calories per glass, making it an ideal low-calorie beverage. Lemon juice has been shown to increase metabolism. While the caffeine in coffee helps you burn more calories by stimulating the process of thermal genesis, in which your body makes heat and energy from the food you eat.