I am currently taking the three subject drugs to counteract my osteoporosis and it appears that they are working in my favor.  I have taken Mycalcin and Evista for the past 6 years and Boniva for 1 year.  (I was taking Fosamax but my prescription insurance made me change to Boniva.)  Within the past year I have gained a significant amount of weight (20 pounds) and, although I am exercising (walking 30 minutes a day, sit ups and push ups daily) and watching what I eat, I cannot shed the weight.  Could this be caused by too much osteoporosis prevention medicine?  Also is there a time limit on how long any of these drugs should be taken?  Thanks for any advice.