If you choose to drink alcohol, beware of the excess calories...
...especially in sugary drinks like cocktails and beer. The best choices for alcoholic drinks are red wine and spirits. If you opt for spirits, have them on the rocks or with water. Skip the mixers.
When you consume alcohol, the body tends to burn less fat and carbs.
Furthermore, alcohol dehydrates the body. So always ensure that you drink a glass of water in between your alcoholic drinks. This will lessen the effects of a nasty hangover in the morning.