Posted 2/21/2021 7:57 AM (GMT -6)
For mysterious weight gain, I think it's smart to look at the meds you are taking. I agree about the steroid being the most likely culprit.
If it's not, though....
I have noticed that the only times I have gained and held onto weight (I'm very small, too, normally) have been when I am dealing with gut dysbiosis, which for me is often asymptomatic aside from weight gain and mood symptoms, yet quite glaring on stool tests. Maybe the antimicrobials you've been taking have depopulated the gut flora and pathogenic bacteria have taken over, preventing proper absorption and processing? I have used herbs to kill the overgrown "bad stuff," and prebiotic and probiotic supplements and foods to help repopulate the "good stuff," which always has worked for me. Just another angle to consider.
Another thought is to check your thyroid with a complete thyroid panel (free and total T3, free and total T4, thyroid antibodies, and TSH). Hypothyroidism (or subclinical hypothyroidism) can cause weight gain.
You don't mention any SSRI meds, but those can cause weight gain as well.
When I was studying midwifery, I learned that the body holds onto an additional ten or so pounds while nursing so that the body will have enough fat stores to produce nutritious milk in case of food shortages. Smart! And with the hormonal disarray I have experienced as part of chronic illness, I would not be surprised if sometimes a body in crisis also holds onto extra fat in order to safeguard itself.
My partner lost ten pounds of belly when he started an autoimmunity-reducing dietary protocol (based on Brooke Goldner's book Goodbye Lupus). He's eating the same amount of calories, but the inflammation and (for lack of a better term) sludge in his gut just jumped ship during week one. It's possible that some of the things he was eating a lot of previously were bothering him at a level he didn't notice. Is there anything in your diet that could be contributing to inflammation?
I hope that you solve the mystery. I know it can be so unsettling when bodies do unfamiliar things!