Julian Shapiro, YCombinator alum, has a very nice guide to building muscle.[0]

The gateway drug to the HIT tradition, which began with genius Arthur Jones and Nautilus in the early 1970s, is this video presentation by Doug McGuff[1], author of Body by Science[2]. Whether you follow a HIT protocol or not, you should be familiar with the theory covered in Body by Science. Doug covers the definition of fitness and health (which is unusual right there for a fitness book!), the confounding effects of genetics, fat metabolism, and much, much more. The High Intensity Business podcast has all the leading figures in exercise research as guests, with a rich back catalog and very detailed links in the show notes.[3] And if you plan to do this for the rest of your life, give your future joints a break by not destroying them in your youth.[4][5]

[0] https://www.julian.com/guide/muscle/intro

[1] https://youtu.be/2PdJFbjWHEU

[2] https://www.amazon.com/Body-Science-Research-Strength-Traini...

[3] https://highintensitybusiness.com/podcasts/

[4] https://www.amazon.com/Joint-Friendly-Fitness-Optimal-Exerci...

[5] https://www.kickstarter.com/projects/billdesimone/the-joint-...

It doesn't take much time to exhaust yourself physically, at least to exhaust specific muscle groups. Systemic exhaustion (steady state exercise, like running) is another matter. It doesn't even cause sweating, as it is over too quickly. I have been experimenting lately with pushups to failure just before I turn out the lights and climb into bed. By failure, I mean MMF (momentary muscular failure), not being able to repeat the motion as hard as I try. An alternative is body weight squats by the bed, to failure. Pick the range of motion to be in the hard (low) part of the squat, move slowly (SuperSlow protocol is 10 seconds concentric, 10 seconds eccentric) to failure, and make it hard enough to fail in less than 90 seconds. Crawl into bed and fall asleep easily (after your heart stops pounding). Of course, you will also build muscle mass over time, which doesn't hurt.

[0] https://www.youtube.com/watch?v=2PdJFbjWHEU

[1] "Body by Science: A Research Based Program to Get the Results You Want in 12 Minutes a Week" https://www.amazon.com/Body-Science-Research-Strength-Traini...

Intensity is 80-90% of the determinant of a muscle's adaptive response to load. If you plan to get somewhere near your genetic potential in strength and size, you will need to use rather high intensity to deeply fatigue ("inroad") the muscle. But you also have to not repeat that stimulus for days to a week, to allow recovery in people like us with middle of the bell curve genetics. The ideal profile for building strength is exercise that is intense, brief, and infrequent. Yes, it is unpleasant for a couple of minutes per muscle group, once or twice a week. So what? Do you enjoy brushing your teeth? Or do you just do it and get it over with? Note, this is for strength training. Skill building for sports, or general physical activity, is a different protocol, depending on the activity.

One of my favorite recent book titles is "If You Like Exercise ... Chances Are You're Doing It Wrong: Proper Strength Training for Maximum Results"[0], which is another book about the work of exercise genius Arthur Jones, inventor of Nautilus and MedX equipment.

[0] https://www.amazon.com/Exercise-Chances-Youre-Doing-Wrong/dp...

[1] https://www.youtube.com/watch?v=F7GB3h82tcQ

[2] https://www.amazon.com/Body-Science-Research-Strength-Traini...

I like your reference to catabolic/anabolic processes. Alas, you then made some incorrect claims.

>you can't lift weights and gain muscle (i.e. grow) without also gaining fat

Of course you can. I'd be happy to share my Google sheet of daily weight, losing about 0.06lb/day, and my BodPod measurements showing going from 28% to 20% body fat while gaining 2.5lbs of muscle mass. Sarcopenia would have taken another 0.5lbs of muscle in that one year period.

Drew Baye has several articles on losing fat while gaining muscle[0]. In the first few pages of Body by Science[1], Doug McGuff defines health as (1) the absence of disease and (2) a balance between anabolic and catabolic processes. Except McGuff makes it clear that almost the entire population in the developed world lives in a catabolic energy state, eating way more than we need, never flushing the stored glucose out of our muscles, the tank is always full[2]. But while that is happening, sarcopenia [catabolic] is removing muscle mass as we age.

[0] http://baye.com/building-muscle-losing-fat/

[1] https://www.amazon.com/Body-Science-Research-Strength-Traini...

[2] https://www.youtube.com/watch?v=2PdJFbjWHEU