Final answer:
Alcohol consumption leads to dehydration by inhibiting the release of ADH, a hormone that helps the body retain water.
Step-by-step explanation:
Someone who has consumed a lot of alcohol becomes dehydrated because alcohol inhibits the release of antidiuretic hormone (ADH). ADH is a hormone that is central to retaining water in the body. When its release is inhibited, the body fails to conserve water efficiently, leading to an increase in urine production and subsequent dehydration.
Alcohol acts as a diuretic and the more you drink, the more ADH production is decreased, thereby causing the kidneys to release more water.