<human>: Can you provide a brief overview of the text?

My gf and I have been together for nearly 6 years.  I'm fit, and she has always been slim, although not necessarily active.  She has always been a comfortable 110lbs at about 5'4", and looks fabulous.  I'm not a superficial person, and have dated heavier women in the past.  I hope I won't be judged as an asshole for my post, but we'll see I guess.

Since about December 2014, she has discovered that putting Bailey's in her coffee is the most exciting addition to coffee since sugar.  Bailey's has ~150 calories per 1.5 oz.  She drinks 4-5 of these things a day, usually with at least 1.5oz or more per cup (based on the size of the bottle and needing to buy a new one every few days).  I figure she is taking in ~600-750 calories a DAY from this stuff alone.  Note this is after work, and there is no driving involved.

At first I didn't really care, weight fluctuation is a normal thing.  I bought a digital scale for myself last fall in order to keep my training and personal health in check.  She weighed herself the day I got it last November and was sitting at 109.  Last night she weighed herself in at 129 lbs.  She has gained 20lbs in two months from drinking this stuff.  

Nothing else has changed, work has been good, stress appears to be normal, and our relationship is healthy.  My challenge is that I fear she won't stop.  She has already put on a good amount of weight (her pants don't fit, so she just bough new pants).  I still find her attractive, but I fear if this continues, I may not at some point in the future.

How do I sit her down and talk to her about this?
<bot>: GF is drinking 600 calories of liquer a day and has gained 20lbs in two months.  Not sure if I should talk to her about it before it gets really out of hand. (and no, she is not pregnant)