A1C is super-easy and common, you might look into it as well.
I try and get as much milk in as possible around workouts, plus I'll pop a couple lactase pills just to help my system deal with the quantity in a more... socially acceptable way. On non-workout days, i usually end up drinking less (still a quart at least), often drinking it in 2 halfs somewhere throughout the day. It's not really much of a science. I did full-GOMAD last year for a couple months and put on probably 10lb of muscle and 10lb of fat.. tho the insulin resistance and acne got pretty bad toward the end. It's a pretty stark difference when I'm eating clean paleo (no dairy). Super-clear skin, healthier appearance, rarely get hungry, etc.. I just have trouble putting on muscle, even when I'm eating 'enough'.