Ok so weight, in males, is going to increase estrogen & decrease testosterone. Not a good combo. Unfortunately dieting also can also decrease testosterone.
I picked up & read this book (and others) in my late 20’s. I don’t agree with his protocols (IIRC he advocates for something other than the shots), but the information is invaluable:
Testosterone for Life: Recharge Your Vitality, Sex Drive, Muscle Mass, and Overall Health https://www.amazon.com/dp/0071494804/ref=cm_sw_r_cp_api_glt_fabc_7ARRHJ79EEAS3GV1VMF2?_encoding=UTF8&psc=1
The signs are going to vary, but libido is the big one, IMO. So he’s become sexually reactive, it sounds like, meaning he probably very infrequently gets horny. His package will react to external stimuli but if he gets too much in his head (ex. He worries about being able to finish) then he’ll more easily go soft - even with testosterone this can happen if a dude is too much in his head, but it’s a lot easier if he’s got low testosterone.
Not to get too personal but he’s still getting morning wood every morning?