If I am dieting and training, everything is going smooth, then some stress at work causes a hiccup and I get up in the middle of the night to devour a half gallon of ice cream, is it ok to promptly go puke this up? I did this last night. Pretty common really. If I eat clean I'm alright, but when I cheat I feel this sense of urgency to get it OUT of me and I vomit it out. I can't be the only one...
In all seriouness, there's nothing wrong with eating the ice cream, however, there is something wrong with throwing it up. Your body might be craving some nutrients that you are deficient in and ice cream being a dairy product might contain it e.g. calcium etc. I often found myself craving bread when I'd limit my diet to certain foods, I soon realised it wasn't necessarily carbs I was craving, it was the B vitamins or whatever in the wholegrain bread as I was limiting red meat and such. I'd find myself eating 4-5 pieces of toast in the middle of the night at the age of 17, not realising why I would do it. I was still growing and my body was screaming out that I couldn't afford to miss out these vital nutrients! That's why whether I'm dieting or bulking I eat a varied diet everyday.
I don't cut out any kind of food or macronutrient for that matter, this is where TA and Wavelength are on the ball with diet. As long as you cover your nutritional bases, that ice cream won't harm you, just figure out the calorie content and have a weekly total in mind, so you can afford to have a few days of overeating or whatever and make up for it on other days. People have to get over the notion that you can simply throw foods into the category of "good" or "bad" or "healthy" or "junk" without looking at the nutritional content and automically presuming that if it has any kind of sugar, it's bad. The only "junk" involved is the rubbish that is fed to you by certain "experts".