Alcohol is not permitted while on Phase 1 and 2 and must be avoided while you're in ketosis. During ketosis, your liver is busy converting the fatty acids being released from your fat cells into ketones that can be burned by your body for energy.
It's also busy converting protein (and sometimes fats) into glucose for those organs that have to have glucose to operate. As well as busy doing all of the other functions that it is responsible for. Alcohol is a toxic substance.
Your liver immediately focuses on removing it from your body and puts other things on hold - such as creating the glucose your brain and other organs need. Hypoglycemia can result and if it happens while you're driving, it could be especially dangerous.