Theoretically body fat wouldn’t have an effect on the protein synthesis increase from anavar or any other anabolic. There are some things to consider with higher Bf though. 1. The cosmetic effect from things like masteron or even anavar are much less noticeable under a thicker layer of fat. 2. Generally having higher bf can be associated with higher bp, heart rate, etc. this is no good when it comes to dealing with potential side effects from AAS. 3. Higher bf means more aromatization of test into estrogen. Anavar doesn’t aromatize, but you get my point. And lastly, gear only helps the process you should already be deep into, just adds some octane booster to the engine so to speak. That’s why people always recommend taking things as far as one can naturally before deploying chemical agents.
Just my opinion.