Gaining weight is always possiple as long as you are eating a surplus of 250-500 calories a day. Just find your maintenance level and eat 250-500 more (lean) calories after that. your maintenance level is what you would normally eat per day.
If your working out a majority of those calories will go for repairing your muscle tissue and whatever. Of coarse if you arent they will turn to fat.
You said you cant lift much? That will change if you train, rest, and eat right dont worry about lifting too much too fast.
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