Hydration is the process of ensuring the body has enough water. Hydration is important for all the cells in the body, which use water for numerous functions like removing waste and taking in nutrients. While the liquid component of many drinks, and even certain foods, can help hydrate the body, quite a few liquids can have the opposite effect.
Drinks and ingredients that act as diuretics, which are substances that increase urine production, may have a dehydrating effect if a person does not take care to balance them with adequate hydration from other sources. Drinks containing high amounts of alcohol, caffeine, and sugar are most likely to perform as diuretics in the body and promote dehydration. Below is a list of drink types that fall within these categories.
Alcoholic drinks: Alcohol acts as a diuretic in the body. This means it encourages the body to remove more fluid through urine than normal. As the body processes alcohol, it encourages extra urination to help remove alcohol and its waste products from the body quickly.
Excerpted from Medical News Today