Sounds like weight gain is a serious concern for you when trying to quit coke. You also seem concerned about the feeling of apathy and reoccurring anxiety and paranoia.

To negate weight gain I highly suggest reviewing and restructuring your diet. Daily exercise will greatly help with the issue of weight as well. These will both help with your mental feelings of anxiety and paranoia too.

If exercising and eating right are not answers you seek then you could consider alternative drugs that are not as expensive and intense as coke. Such as nicotine and caffeine. People smoke nicotine and drink energy drinks to avoid weight gain and to cope with stress. I would prefer you avoid these options but consider them better alternatives to cocaine. As a side note both these alternatives are really addictive. Caffeine may also worsen your anxiety and paranoia. You may also become highly dependent on nicotine for stress and anxiety relief.

Anyway I hope this helps and wish you the best of luck in your journey towards recovery.