Testosterone, DHT, and Gains: What Actually Builds Muscle

In fitness communities, DHT has achieved almost mythical status as the "alpha hormone"—the androgen that makes men masculine. The implication is that blocking DHT (as finasteride does) will feminize you, rob you of aggression, and destroy your ability to build muscle.

This narrative fundamentally misunderstands how androgens work in different tissues. Let's set the record straight with actual biology.

The Androgen Hierarchy

Your body produces several androgens, but two dominate the conversation:

DHT is indeed more potent at the androgen receptor—about 3-5x more binding affinity than testosterone. But potency isn't the whole story. Location matters enormously.

The Tissue-Specific Truth

Here's what the "DHT is everything" narrative misses: DHT is created locally in tissues that contain the enzyme 5-alpha reductase. Different tissues have vastly different amounts of this enzyme:

Your muscles primarily "see" testosterone, not DHT. The conversion happens in other tissues—scalp, skin, prostate—but not meaningfully in muscle. This is why blocking 5-alpha reductase (what finasteride does) affects your hair and prostate but not your biceps.

What Drives Muscle Protein Synthesis?

Research on androgen receptor activation in muscle tissue shows:

• Testosterone is the primary anabolic signal in skeletal muscle
• Muscle cells don't significantly convert testosterone to DHT
• Androgen receptor activation in muscle correlates with circulating testosterone, not DHT
• Studies blocking DHT show no decrease in muscle protein synthesis

Natural Experiments: 5-Alpha Reductase Deficiency

There's a genetic condition where males are born without functional 5-alpha reductase—they produce virtually no DHT their entire lives. What happens to their muscles?

Nothing remarkable. These individuals develop normal male muscle mass and strength at puberty, driven by testosterone. They do, however, have underdeveloped prostates and don't experience male pattern baldness.

This natural experiment confirms what the biochemistry predicts: DHT is not essential for muscle development. Testosterone handles that job.

The Finasteride Testosterone Boost

Here's an irony lost on most gym bros: finasteride actually increases testosterone levels slightly.

The mechanism is simple: normally, some of your testosterone gets converted to DHT. When you block that conversion, that testosterone stays as testosterone. Studies show approximately a 10-15% increase in serum testosterone levels on finasteride.

If testosterone is what drives muscle growth (which it is), and finasteride increases testosterone (which it does), then the theoretical argument for finasteride helping gains is actually stronger than the argument for it hurting them.

(In practice, the increase is modest enough that it doesn't meaningfully change muscle-building outcomes—but it certainly doesn't hurt them.)

What DHT Actually Does

DHT isn't useless—it's crucial for certain functions:

• Male pattern baldness: DHT miniaturizes hair follicles (bad)
• Prostate growth: DHT drives prostate enlargement (bad in excess)
• Body hair: DHT promotes body/facial hair growth
• Sebum production: DHT increases skin oil (acne connection)
• Sexual development: Critical during fetal development and puberty

Notice what's NOT on that list? Muscle building. Because that's testosterone's domain.

Addressing the "But I Feel Weaker" Objection

Some men swear they felt weaker on finasteride. Possible explanations:

• Nocebo effect: Expecting weakness can create perceived weakness
• Psychological factors: Anxiety about side effects affects training motivation and intensity
• Coincidental timing: Natural training plateaus blamed on medication
• Sexual side effects: If libido drops (rare), that might affect gym "aggression"

When studied objectively with strength testing and body composition analysis, finasteride users show no measurable difference from non-users. Subjective experience doesn't always match objective measurement.

The Bottom Line

Testosterone builds muscle. DHT doesn't, at least not meaningfully. Blocking DHT with finasteride protects your hair without sacrificing your gains.

Don't let misunderstanding of basic endocrinology cost you your hairline. The hormones you care about for the gym (testosterone) are preserved—even slightly elevated—on finasteride. The hormone being blocked (DHT) was never your muscle-building ally to begin with.

References

• Research on androgen receptor expression in skeletal muscle.
• Studies on 5-alpha reductase tissue distribution.
• Clinical observations of 5-alpha reductase deficiency syndrome.
• Finasteride pharmacology and hormone level effects.