Increased belly fat is most definitely a side effect of Tymlos--although the drug company does not list it as so. From what I understand, if it wasn't prevalent in the clinical trials, then they didn't have to show it as a side effect. I have been naturally thin my whole life, and even after each of my children were born, I would go right back down to my regular size 4. But within 3 months of starting Tymlos, I began to slowly gain belly fat and actually had to go up a size in my clothing just to be comfortable. But as others have said, it will be worth it if the trade off is stronger bones. Hoping the belly fat will disappear when I finish the drug. On a positive note, I had one DEXA after 18 months on Tymlos and my spine improved by 12%, from -3.5 to -2.8 so it's working for me. I am almost finished now and need to make a decision on what drug to go on next, to keep these gains. I cannot tolerate bisphosphonates and cannot take prolia due to some dental issues. My doctor wants me to try Evista so I am now trying to find as much information as I can find before I take it.