Well in a psychological perspective (psych student), you're gonna have to be conditioned again. It takes time, yes. But if you're determined enough to continue the regimen you've been doing, it will take effect eventually. If not and already loosing hope, seek professional help for this. You're experiencing withrawals so it's best to have assistance at this stage.
I suggest talking to doc about ambien will teduce stress and I've heard from my nephew sister and brother who all take it that it makes you hungry.
That's not really true. There is absolutely a physiological withdrawal from marijuana. I am a nuerology student currently, and it is complicated to explain, but basically your body is always trying to maintain homeostasis. so if you smoke pot, which changes the chemical balance in your brain, the body will try to compensate. for example, marijuana increases appetite. your body was probably responding to that with some coping mechanism to decrease appetite. therefore, when there is no more marijuana, the coping mechanism is still there in preparation for it because your body does not know the marijuana is no longer coming. it more likely has to do with loss of appetite due to anxiety because pot messes with seratonin levels, but that's more complicated to explaim but still the same basic idea.
Look, anything's possible, but marijuana doesn't have a physiological withdrawal. It's not an addictive drug. It does, on the other hand, make some people hungry (the munchies). So I doubt your problem is the mj, it's more likely whatever reason you found to smoke so much in the first place. As for your weight, making weight for sports isn't healthy, it's just done. Healthy is whatever your natural weight is, but of course if you stuff yourself you're going to feel ill and have problems digesting it. You need to build the amounts up slowly, and turn it into muscle. The problem with too much muscle for you is, kickboxing depends on great flexibility, and huge muscles can get in the way of that. Otherwise, you'd just get fat, which won't help you do anything but get slower, unless you want to be an offensive lineman. That's why so many athletes take steroids -- to turn the excess food into muscle. I'd recommend you find your natural weight eating a healthy diet, and go down in weight class in the kickboxing; if you insist on gaining weight for it, eat six meals a day, lots of protein, but realize it's not healthy, and work out in the gym a lot so it turns into muscle, not fat. Since kickboxing is extremely aerobic, as is the training, that will burn off the food you eat quickly, so you have to overeat to maintain weight. On the other hand, if you just want to be good at martial arts, learn how to use motion and leverage for your strength, not your weight. You're not wrestling, after all.