I would have said just eat protein and work out when I was in my teens, 20s and early 30s too.
I am 48 and not on testosterone, yet. I actually can't recover at this point from workouts that burn enough calories vs working out less but more calorie restriction in terms of fat loss. Even 60 minute walks cause me to be more hungry to be able to recover from than what I can restrict without walking.
I am at the final death throws of natural and not being on TRT basically. I have been pushing TRT out since my late 30s but have gone way too far.
I think the TRT threshold probably be when you can't outrun calorie restriction by working out. For me, that has probably been since 43 or 44. By 46 for sure.
Personally, I don't need GLP-1s. So many people though do.
I think it's extremely probable that the most rapid losers are running the largest calorie deficit and also the largest protein deficit.