Confused About Tirz and Muscle Growth

[UghItsStupidNIHateIT]

I keep seeing claims that tirz causes major muscle loss, and that the fix is high protein intake plus weight training. But my actual goal is to build strength while taking tirz.

What's confusing me: my legs are clearly getting stronger, and I can't figure out why. On the 45 degree leg press I'm now doing 615 for 10 reps, which is up from 400 when I began 2 months ago. Yet my bicep curls have stayed at 10 pounds the entire time. I lift full body with weights 2x per week, practice yoga, and run several times weekly. On my legs, the muscle is beginning to show through the fat. My arms, though, are basically doing a ramen noodle impression. Could it be that muscle loss is happening only in my upper body?

35 y/o 5'4" female.

HW: 240

CW: 210

On tirz since 3/9/26.

 

[cheaperseeker]

Dr Google had this to say:

[[Q1]]

The gap in difficulty between training arms versus legs boils down to a handful of main reasons:

Starting Strength Is Lower:

For the lower body, women usually have roughly 60–80% of men's strength, yet for the upper body that figure drops to only about 40–60%. So your arms begin from a far smaller base, which makes early progress feel like a steeper climb.

Everyday Use and Mechanics:

Just walking, standing, and supporting your own weight against gravity keeps your legs working all day. That means lower-body muscles build more endurance and baseline strength as a matter of course. Arms, by contrast, mostly handle lighter tasks that need fine motor control.

How Muscle Fibers Are Made Up:

Biological differences, such as a greater share of Type 1 (endurance-oriented) fibers in the lower body, make it simpler to generate force with the legs than with the arms.

Upper-Body Muscle Amount:

Women carry less muscle tissue naturally in the shoulders, back, chest, and arms. Since there is less tissue and surface area to start from, achieving visible strength or 'tone' calls for steady, progressive overload.
[[Q2]]

 

[cheaperseeker]

Also, that's not a silly thing to ask.

A large portion of the exercise knowledge we've been given comes from research that only included male participants, which means much of it doesn't translate well to women.

 

[amosmylove]

Seems pretty typical for a woman. It can be annoying, but a powerful lower body is great as well. Your progress really impresses me!

For a female, I've always been quite strong, upper body included. Curls with 35lbs for reps, bench reps at 140lbs, pull ups at 165 lbs, and so on. That was during highschool and college, back when I was an athlete. Then across the past couple of years (honestly, more like 10 years ) I quit nearly all sports and every bit of working out because of serious autoimmune disease attacks, and these days I'm far, far weaker. I figure getting back to an above average upperbody, if or when I try, will be a struggle.

Every one of my friends from my sports teams, apart from a couple in college who were amazing lady freaks, was ordinary and gained muscle just the way you're describing.

What I'd suggest is keep your arm/upper body days steady so your strength holds, and throw in some heavier weights even when only a couple reps are possible, then drop back to what's easier to handle. Don't abandon your upper body, but you should absolutely expect most of your gains to appear in your lower body.

 

[staffn1]

Do not treat heavier lifting as the same thing as building muscle; those are two separate matters. This matters even more when calories are restricted, since putting on muscle becomes considerably more difficult under those conditions.

 

[Neptide]

UghItsStupidNIHateIT said:

I keep seeing claims that tirz causes major muscle loss, and that the fix is high protein intake plus weight training. But my actual goal is to build strength while taking tirz.

What's confusing me: my legs are clearly getting stronger, and I can't figure out why. On the 45 degree leg press I'm now doing 615 for 10 reps, which is up from 400 when I began 2 months ago. Yet my bicep curls have stayed at 10 pounds the entire time. I lift full body with weights 2x per week, practice yoga, and run several times weekly. On my legs, the muscle is beginning to show through the fat. My arms, though, are basically doing a ramen noodle impression. Could it be that muscle loss is happening only in my upper body?

35 y/o 5'4" female.

HW: 240

CW: 210

On tirz since 3/9/26.

I get where you're coming from — I've dealt with that exact situation too. It just happens sometimes. Make sure you're getting plenty of protein, creatine, and solid overall nutrition. For muscles to develop, they need fuel. For me, NAD+, Lipo-C with B12 have made a difference. I also rely on steak, eggs, and complex carbs. When you don't have an appetite, it's tough, but you still have to put in the effort. If you're not seeing growth, increase the weight you're lifting. To actually grow, I have to take resistance training to failure. Keep pushing.

 

[Smiter]

When you're working the upper body's smaller muscles, your training approach has to change.

For bigger biceps, perform 6 sets of 3 reps, followed by 2 sets of 5 reps... The opening 6 sets should be at 85% of your one rep max...For the final 2 sets, use 70% of your 1RM, but execute them with an explosive concentric movement and a slow eccentric phase. Oh yeah, rest at least 4 minutes between sets. During that rest period, take long, deep, slow breaths.

 

[sheilarae74]

That's a fair thing to ask. When I was younger, my legs could handle 300lbs, yet a 50lb bench press was beyond me.

 

[Cumulus]

UghItsStupidNIHateIT said:

I keep seeing claims that tirz causes major muscle loss, and that the fix is high protein intake plus weight training. But my actual goal is to build strength while taking tirz.

What's confusing me: my legs are clearly getting stronger, and I can't figure out why. On the 45 degree leg press I'm now doing 615 for 10 reps, which is up from 400 when I began 2 months ago. Yet my bicep curls have stayed at 10 pounds the entire time. I lift full body with weights 2x per week, practice yoga, and run several times weekly. On my legs, the muscle is beginning to show through the fat. My arms, though, are basically doing a ramen noodle impression. Could it be that muscle loss is happening only in my upper body?

35 y/o 5'4" female.

HW: 240

CW: 210

On tirz since 3/9/26.

My upper body is terrible as well. It shrinks more quickly for me, though I have a condition in that area, so what I go through isn't the same as what you do. For building gains, what methods have you given a shot? Adding weight in tinier steps, longer time under tension, higher reps? Or preacher curls just for kicks?