Anecdata here but a few months ago I started eating "one meal every other day" (a massive ribeye with butter and eggs. i have no idea what the calories or protein or whatever are.). I had been strength training for a while without dietary control.

I'm severely obese. Significantly less so than I was when I started fasting, but still over 35 BMI.

I think I've gained a small amount of muscle? It's definitely slowed down since before I was fasting, but lifts are progressing still. It may just be skill progression but these are simple lifts that I'm pretty familiar with (overhead press and deadlift), and I feel like I'm still gaining real strength.

I don't know how to judge muscle size really, especially since I'm losing body fat which is obviously making them look more pronounced.

I do take one "testosterone-boosting 'supplement'" (the main one). I've been running a test level of around 900.