I have rumatoid arthritis and im tacking prednasone and I swel up meaning igain to much weight and I eat very little soud I tack weigh loss medicati?

No. Prednisone can cause some weight gain by increasing appetite (a little through water retention). Best approach would be to talk w/ your rheumatologist to discuss whether a lower dose is feasible (may need to add other meds to achieve this). Would also meet with dietician, as portion distortion and hidden calories may be adding to your weight. I do not recommend weight loss pills.
Diet and exercise. It is difficult to control your weight while on prednisone, so the best thing to do will be diet and exercise and if possible be on the lowest Prednisone dose that will control your symptoms.