Hello Doctor, I Am 24 Years Female, 164cms Ht And

Hello doctor, I am 24 years Female, 164cms ht and 75kgs weight. I have PCOS. I have some pain in both my knees and I have been advised to taken cartigen forte for 3 months. I want to reduce my weight and would like to know if I can go to gym and do exercises like cycling and other exercises involving knee. Please advice.