Arnold Schwarzenegger has been vocal about debunking myths about fitness and nutrition, and this time, he refuted some fascinating myths about gender roles, including the claim that women gain fewer benefits from protein than men.

Schwarzenegger's Pump Club newsletter from June 9, 2026, the seven-time Mr. Olympia broke down the science — and the results may surprise you.

"It's an old assumption dressed up as biology: men have testosterone, so women's bodies turn protein into muscle differently," Schwarzenegger wrote, before dismantling the claim entirely.

Schwarzenegger cited a muscle protein synthesis study showing identical post-workout responses in men and women. Despite men registering testosterone levels approximately 45 times higher in the hour following exercise, the muscle-building response was identical. "The muscle-building response didn't follow it," he noted.

Schwarzenegger said, plain and simple, that muscle growth and hormones are only minimally correlated, and that it is mechanical tension from resistance training, with adequate nutrition, that actually builds muscle.

"The pathway for growth first answers to the work you do and how close you train to failure, and then your nutrition supports that process."

Schwarzenegger isn't speaking from intuition; there are two additional trials that back his point. Analysis of randomized studies showed that when extra protein is introduced to the diet of a person who performs resistance training, muscle density increases irrespective of sex.

Another study revealed that women's muscle gains are very similar to those of men.

Two more trials supported his claim: a meta-analysis of randomized studies revealed that strength increases with extra protein intake coupled with resistance training, independent of sex, and a 2025 meta-analysis revealed that women's muscle gains were almost on par with men's.

The takeaway, per Schwarzenegger, is straightforward: protein requirements scale with body size, not gender. "A smaller body needs fewer grams, not a different target for its size."

Why Schwarzenegger Says Testosterone Isn't the Master Switch for Muscle

Arnold Schwarzenegger outright rejects testosterone as the ultimate muscle-building hormone, and the scientific data confirms him.

In the same newsletter mentioned earlier, Schwarzenegger said that mechanical tension and amino acid intake do more for muscle growth than circulating testosterone levels.

"Testosterone gets the credit as the master switch for muscle, but that's not what matters most, and it's not even close," he wrote.

The claim came up while addressing protein use in women versus men, with research showing identical post-workout rates of muscle protein synthesis despite a massive hormonal gap between the two groups.

His message remains consistent: train hard, get enough protein for your body size, and trust the process regardless of gender.

Do you also agree with Schwarzenegger on this?

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Written by

Proma Chatterjee

Edited by

Ashvinkumar Patil