Good morning @charlie01 I’m so sorry you were diagnosed with myositis. Autoimmune disease can be so difficult to deal with. Has your doctor recommended physical therapy to help with the muscle weakness? Or, are you a walker? Physical activity is so important if you have an AD. And 1 or 2 naps a day can really help! I included these two sites that can give you more information:
https://my.clevelandclinic.org/health/diseases/15700-inclusion-body-myositis
https://rarediseases.info.nih.gov/diseases/3896/inclusion-body-myositis
You said that you’re on prednisone and Mycophenolate. So am I. I started on heavy doses of prednisone for my AD. The prednisone finally brought my disease under control, but it caused major problems—osteoporosis and cataracts. I’m tapering off the prednisone and the Mycophenolate should take over and keep things under control without the side effects of prednisone.
You might also want to check out The Myositis Assoc. https://www.myositis.org.
How are you coping with this diagnosis so far?

Hi @charlie01, I'd like to add my welcome along with @becsbuddy. You'll notice that I moved your question to this existing discussion about BMI
- Inclusion Body Myositis: I'd like to talk with others https://connect.mayoclinic.org/discussion/inclusion-body-myositis/

I did this so you can connect with @mklam @catharbert @tarmansbks who are talking about treatments and things you can do for yourself to help manage Inclusion Body Myositis.

What symptom or symptoms do you find the most challenging at the moment? What helps?