What causes a rapid weight gain?

Hey guys, I posted this question on the "over 30" board, but nobody seems to venture there much. Here's my inquiry...

What causes a rapid weight gain? I'm not a user (yet) and I've been hovering around 250lb for about a year now while trying to bulk up and get ready for my first cycle(s), but it seems like the holidays jump started something to get me to put on 20lb in just under 2 months - I weighed 270 last night, and I'm sad to say not all of it is muscle, though my legs feel incredibly harder. Funny thing, I don't really look any bigger.

I haven't changed my diet, but my workouts seem to be more intense lately, and I'm using heavier poundages. I had taken off the holidays from working out to give my body a rest. Is my body re-adjusting to lifting after a break? Is it normal to come back stronger after a break and does it affect your weight gain?

Any chemists want to take a shot at this one? BTW, I'm 5'11".

Try the diet forum, bro you should get some responses there.

yeah bro diet forum

I'll answer one part of your post..

It is very common to come back stronger after taking a few weeks off from the gym. The body needs time to rest and heal and a few weeks off is just what the doctor ordered sometimes.