Oh my - his instructions should have been WAY more specific.
NO ALCOHOL AT ALL FOR A YEAR. That's the general rule. While you are in the weight loss window, your liver is processing toxic byproducts of fat digestion, as well as whatever fat-soluble crap was stored in your adipose tissue - PCBs, hormones, dioxin, herbicides, pesticides - which is released into the bloodstream when you release the fat it is dissolved in. You do NOT want to stress your liver, which was probably already suffering from steatohepatitis from 40+ years of obesity.
Having said that, a half glass of champagne on your anniversary AFTER SIX MONTHS (probably) isn't going to kill you.
And having said that, alcohol has 7 calories per gram, 100% of which are absorbed.
And even more, you will get a LOT more drunk very quickly - though it will likely wear off more quickly. Be VERY careful when you eventually DO decide to have a drink - say around Thanksgiving or New Year's at the earliest, and have your first drink at home - not at a restaurant or party, where puking unexpectedly would be bad form. And transfer addictions are VERY common in bariatric patients.
Here's the worst news of all - as your four-years-older-sister - in the last year or so, I have become increasingly "sensitive" (I refuse to say allergic) to alcohol in almost every form. I get very unpleasantly hot and sweaty, especially around my face and hair, and it is taking all the damned fun out of mimosas and mai tais. Even a beer isn't going down well, nor a glass of wine. I'm VERY annoyed about it.