Yep, one or the other. Kinda sucks, but I think it's kinda cool cause when I start getting fat, I can just say I'm bulking! LOL! The wintertime is definitely the time to bulk, and with all the holidays, very convenient! As far as the eating without thinking thing, like I said, I'm just like you!!! I was blessed with a high metabolism, but I realize that is coming to an end, so I'm trying to get a jump on that now, rather than playing catchup later. I'm hoping that whatever works for you, will work for me, so make sure to let me know! LOL!
As far as gaining lean muscle mass, I would say watch the carb timing, and don't overdo it. Carbs are great, but also have a tendency in a lot of people to cause bloating and fat storage unless they are used (hence no carbs after 5:00, as they won't be burned up, and your body has already stored the carbs from earlier, and you want to use them up before bed time). I look at the shakes as gap-fillers (except the post-workout; these are necessary due to the anabolic windows that opens after a workout). So, figure out your diet, add in the post-workout shake, and go from there. So, if you're doing a 40/40/20 diet (that's 40% protein/40% carbs/20% fat) which I did recently, or whatever diet you choose, figure out how many calories you need for maintenance at your current weight, add a few hundred calories, and then calculate your macros. If you can't get enough protein in your diet, then add in a shake to meet your needs. I find I can easily get the protein and fat I need, but I have trouble with carbs!!! And, when that no longer adds mass, then recalculate and go from there. Same with cutting, but subtracting the calories from maintenance. And, what I started doing, is go around the house, and make a spreadsheet of EVERYTHING in the house. Include calories, protein, carbs, and fat. Now, since you know how many calories you need, and the content of those calories, now you can figure out how much to eat per meal, and what to eat. Maybe you ate junk for lunch #1. Well, compensate for that in the rest of the meals. Try to plan the meals out in advance on the spreadsheet, so that you are not caught off guard when you're hungry!!! Hopefully, this helps!
--Brian