What is wrong with my mom?

okay my mom used to be really fat like almost 300lbs so she had gastric bypass surgery i should also mention she is bipolar and on medication but i dont think its working for her anymore. Anyway she has a problem and is putting on weight still. She will have small meals in the day and then gets full then half hour later she will want junk food but wont finish her dinner saying she is too full. it seems she is too full to eat healthy but not to full to eat chips and chocolate bars or whatever other junk food she can get her hands on. Just yesterday she complained that her pjs didnt fit and said it was because she put them int he dryer and they shrunk. I am always bugging her to exercise since i do daily but she will make excuses not to. She will laze around in bed all day to complaining she doesnt feel well and skips work when she just has cramps from the monthly curse. She is driving us all nuts because she wont take care of herself and is always supposedly not feeling well. What can I do about her if she wont help herself and we have all tried everything to wake her up to her issue. Oh yeah another example of a time when she made an excuse not to exercise. I was going to take the dogs for a walk and told her she should come with me, about 10 mins in she complained it was too cold and went back home. It was not cold at all and it just made me extremely frustrated at her. How can anyone not give a **** about how they look and the fact they are gaining weight. Please answer this anyone but please dont make rude comments...i wouldnt make rude ones about your mom.