I've had Rum and Crystal light powder mix or diet coke. 2 shots worth a night and I've done this on several nights. Maybe 5 cals from the crystal light. Rum, I'm not sure about the cals. But to my surprise I'm still on track and losing at the same ratio if I don't drink.
I'm currently on P2 and this is my second round of P2. My 1st time on P2 I had no drinks at all. This round I've actually had a lot of drinks (all either vodka or rum mixed with zero calorie or very low calorie drinks) and it doesn't seem to effect my losses at all. I've measured and written down daily stats and charts and my 1st P2 and 2nd P2 are nearly identical with my weight loss.
I'm not advising anyone to do this. Everybody's body is different. I'm just stating my experience with drinking and my results were good. Being able to have a relaxing drink or two in the evening is nice. I missed it on my 1st round P2. I'm happy my body hasn't gained from this.
So if you're on the fence and thinking about drinking. Baby steps. Try a tiny bit and see how your body reacts 1,2, even 3 days later. ALWAYS measure and adjust if you see gains or stalls.