How does lifting weights affect a woman's muscle bulk?

Many women resist trying strength training (lifting weights) because they're afraid of getting bulky. Don't worry: sculpting bodybuilder-sized muscles is hard work. Women don't have enough testosterone to easily build the large, bulky muscles that men develop.

If you want to become a body builder, you must work hard at it, repetitively lifting increasingly heavy weights. The good news is that developing even a little more muscle can increase your metabolism and help you manage your weight more easily. Start lifting weights twice a week to see results from more toned, not larger, muscles.
Some women may avoid lifting weights because they are afraid they will bulk up. Those who skip strength training - lifting reasonable weights - are bypassing an important part of physical fitness based on concerns that are typically unnecessary. Women don’t have as much testosterone as men, so it is not easy to bulk up their muscles by lifting weights unless they are trying to do so. If you are still worried about becoming too muscular, use less weight and do more repetitions (10 to 15 repetitions per set).

Women often avoid resistance training for fear they will end up looking like the female bodybuilders seen on television or in print occasionally and fear the excessive musculature those women possess. The truth is though that to develop high levels of muscularity is extremely difficult for both men and women, and especially for women. Female and male bodybuilders combine intense training, strict dietary practices, good genetics and often times anabolic/androgenic steroids to create the hyper muscular look of high level bodybuilders.

To build significant amounts of muscle mass especially for women requires a very high calorie, high protein diet, combined with very heavy high volume weightlifting and high levels of the hormone testosterone which most women only produce in very small amounts. To "bulk up" most women would be required to eat large amounts of food, lift heavy weight most days of the week and use steroids.

Women should not be afraid of or shy away from weight training; it will improve body composition, speed up metabolism, and improve bone mineral density and decrease your risk of developing osteoporosis.

As a woman, lifting weights alone should not make you bulk up. It is common for woman to avoid weight training because they believe it will, but as Phillip mentions above, it can take a lot more than just lifting weights to bulk up. Woman CAN lift weights for the purpose of gaining the benefits of improved bone density and decreased risk of developing osteoporosis as well as improved body composition, as Phillip mentioned, without bulking up. 

So you don’t want to compare biceps measurements with your husband? No problem! Your hormones won’t allow you to. Women, while superior in many ways (could not help myself), we just don’t have the levels of testosterone our gender counterparts do. Therefore, the good news is that you will only bulk up if you train to. Depending on your goal, the type of program you choose will help you create the best results. For example, if you don’t want to get bulky, keep your reps high and your resistance low. Also, keep moving throughout your workout, doing one set right after another (called circuit training). Lastly, make your exercise movements compound, working more than one muscle group at a time. This little trick can save you time and burn some extra calories (all while keeping you looking like a swimsuit model and not a body builder).

It takes a tremendous amount of hard work, special diet and supplementing for guys to bulk up, not to mention the amount of testosterone they are already loaded with. As females with average 92% less testosterone than our male counterparts, it's unlikely that we bulk up so effortlessly that we can't stop it.

Outcome of female's strength training is more likely a lean, athletic look. Isn't that what we are all after?


As a woman if you weight train the likely hood of you “bulking up” is extremely low. So in low in fact that you don’t even have to worry about it.

We see bodybuilders, men or women, in the magazines or on TV after months if not years of training specifically for the purpose of looking big. Most of these professionals, and sometimes people in your own gym, take anabolic steroids, some may take testosterone, many supplements, have a diet consisting of Carbs-Protein-Fat of 40-60-20 respectively or an even higher % of protein in the ratio. Their job is to look that way.

An average woman just doesn’t have the amount of testosterone to bulk up. When you see woman who has a nice physique, shapely arms, and toned abs what you are seeing is a weight lifter who has minimal body fat. The best way to change the shape of your body is to lifts weights. Lifting weights will get you to that toned look.

Marjorie Nolan Cohn
Nutrition & Dietetics

This is probably the most frequent question I am asked when instructing women on fitness and exercise. If you have avoided weight machines, free weights, and even pushups out of the fear of “bulking up”, you’ve been misguided. Ladies, gaining muscle does not mean you will get bulky. In fact, I promise you won’t. Here’s why:

  • Women do not have the amount of testosterone necessary to build large muscles; men do. The average man has approximately 20 times MORE testosterone than you. Testosterone is the reason why men can build large muscles.
  • Think of resistance training as toning. Toning is essentially bodybuilding, without the testosterone. You tone “build” muscles by strengthening them. Strong muscles have a healthy, attractive toned appearance. It does not make muscles bulky.
  • Bulky muscles are built from doing from high-volume, heavy weight-lifting. Lower volume resistance training, meaning lower weights with higher volume repetitions, is designed to build strong toned muscles not bulky ones.

“Bulking up” is dependent on calories. You need to eat more calories in order to create large bulky muscles. Unless you are eating extra calories in the form of protein, and complex carbohydrates, the math simply does not add up.

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Important: This content reflects information from various individuals and organizations and may offer alternative or opposing points of view. It should not be used for medical advice, diagnosis or treatment. As always, you should consult with your healthcare provider about your specific health needs.