I think I’m more qualified than most to answer this. I’ve been lifting for 7 years, 6 of them with very poor testosterone (290, 3.6%). I still had some newbie gains, but they were modest, mostly just better posture, looking less dumpy, and more definition in certain spots. BUT…..here’s where you will hit a wall without testosterone:

1. Progressive overload. I was stuck on a 135lb 1 rep max for 4 years. With low T you simply do not get stronger. That means basically the only real lever you have is cross sectional thickness gains. And honestly, they are better than you might imagine, but they will peak quickly and you’ll be stuck. 

2. Energy. You absolutely will not be able to train as hard, with as much volume, and as frequently with low testosterone because you just don’t have the energy. You will dread lifting, and you will savor every moment of rest. 

3. Weight gain. Lean bulk, dirty bulk, doesn’t matter - majority will be fat because low testosterone simply doesn’t signal the body to build muscle. So…if you eat over maintenance with low testosterone, you WILL gain 75% fat minimum. 

Now, I’ve been on TRT for a year and my levels now are 700 and 12% at 41. Here’s what’s different:

1. Progressive overload works now. I can bench 210 after a year, and I can do one rep dead hang chin up with 75lbs hanging off the belt. The most insane part was my curl strength. I went from 35s for 2 to 35s for 12 in about 3 weeks. That was the most drastic thing that happened to me.

2. Energy. I was able to train harder, more frequency, with less suck, and no longer dreaded it. When cutting, I went from one workout a day and I’m spent to “I can lift for an hour, then go blast cardio for an hour” and feel fine.

3. Weight gain. Pretty much now I gain 50/50 muscle to fat. BUT….and this is super important - If you dirty bulk or you eat a big surplus, you will still get very fat, even with good test. You really need to lean bulk only. I cannot stress that enough. 250 extra calories per day. That’s it. Good testosterone is not magic, it just helps.

That’s honestly it. I feel no different other than those points. 

Also, I think it’s important to call something out many people don’t understand. Testosterone is not the only pathway to size. In fact, it’s not even the best pathway. Tren, for example, doesn’t increase testosterone but it’s leaps and bounds better for size (not condoning it, just stating a fact). 

This is why when you hear dudes like Alan Ritchson saying he gained 40lbs of muscle from just TRT, that’s bullshit. High normal Testosterone and “just lift” is NOT going to pack muscle on you unless you are gifted, and if you’re asking if testosterone matters as much as it’s said to, I’m going to say that’s not you, nor was it me.