You’ve probably heard the claim that women can’t build significant muscle mass. Maybe even believed it. After all, it’s a popular idea in many gyms. But what does science actually say about women’s ability to build muscle?

While it’s true that men often experience larger absolute gains in muscle size when lifting weights, studies show that women can see similar relative increases in muscle size. Simply put, women can build muscle effectively, even if the total amount of muscle gained isn’t as large as what men typically achieve.

To better understand this, let’s break down the difference between absolute and relative changes:

• Absolute Change: This is the straightforward difference between where you start and where you end up. For example, if you increase your muscle mass from 50 pounds to 55 pounds, the absolute change is five pounds.
• Relative Change: This is the percentage increase or decrease based on where you started. So, if you go from 50 to 55 pounds of muscle, that’s a 10% increase.

Since women usually start with less muscle mass than men, the gains in absolute terms might be smaller. However, the relative gains—the percentage increase—can be quite similar. In other words, even if women don’t gain as much muscle in total, the proportion of muscle they gain can match that of men.

What the Research Says

Recent research analysed data from 27 studies, involving over 1,900 participants (both men and women aged 18 to 50). These studies looked at muscle growth (hypertrophy) from resistance training, considering factors like:

• Training experience
• Types of muscle fibres
• Body regions trained (upper vs. lower body)
• Different training programmes

Participants in these studies typically trained two to three times per week, for a period of six to 24 weeks.

The results were clear: men did see larger absolute increases in muscle size. However, when looking at relative percentage gains, women showed similar increases. This means that, relatively speaking, women can gain muscle at a rate comparable to men when you account for their starting point.

Whether you’re lifting lighter or heavier weights, or targeting different muscle groups, the muscle-building potential is there for both sexes. Even adding more sets to workouts only gave men a tiny edge in muscle growth—so small that it was considered almost insignificant.

Muscle Fibre Types Matter

The studies also looked into the changes in different types of muscle fibres:

• Type 1 Fibres: These are more about endurance and didn’t show much difference in growth between men and women.
• Type 2 Fibres: These are the power and strength fibres, and women showed more growth in these compared to their type 1 fibres. Men, on the other hand, showed balanced growth in both fibre types.

While these findings suggest that women might develop certain muscle fibres more than others, the researchers caution against drawing too many conclusions, as more research is needed.

Key Takeaways

1. Women Can Build Muscle: You don’t need to worry that lifting weights will make you look like a bodybuilder overnight. While women may not bulk up in the same way as men, they can still gain noticeable muscle. These gains can improve your strength and muscle definition—enough to see a difference in the mirror and feel it in everyday tasks, like carrying heavy groceries or lifting a suitcase.
2. Men and Women Benefit from Similar Training Approaches: The old advice that women should use light weights and high reps to avoid bulking up is outdated. Both men and women benefit from progressive overload—gradually increasing the weight, reps, or sets over time. This approach helps build muscle and strength effectively for everyone.
3. Consistency is More Important Than Perfection: You don’t need a perfect routine to see results. Even a modest amount of strength training can make a significant difference. Aim for two to three strength training sessions per week, with a few sets of exercises that target different muscle groups. Make sure the last few reps of each set feel challenging (around a 7 to 9 out of 10 effort).

The myth that women can’t bulk up or build significant muscle is just that—a myth. While women may not gain as much muscle mass as men in absolute terms, their potential for relative muscle growth is strong. By focusing on consistent strength training and challenging yourself over time, you can build muscle, increase strength, and enjoy the many benefits that come with it. So go ahead—lift those weights and feel confident in your muscle-building potential!

Ready to bulk up and take your strength to the next level? Book a consultation with a health coach for personalised advice on how to optimise your workouts and achieve your muscle-building goals. Don’t worry, it’s absolutely free!

References:

Can women pack on muscle?. Precision Nutrition.

Refalo MC, Nuckols G, Galpin A, Gallagher I, Hamilton DL, Fyfe J. Biological Sex Differences in Absolute and Relative Changes in Muscle Size Following Resistance Training in Healthy Adults: A Systematic Review. SportRxiv.