Despite weight training being beneficial for building strength, maintaining bone density and reducing body fat, some women are hesitant. A common concern among women is that lifting weights will cause them to put on significant mass and make them appear bulky. In reality, however, nearly all women lack the body type and hormonal makeup to put on serious muscle. The low percentage of women that do get bulky with weight training either have naturally higher levels of muscle-building hormones or are taking supplements to facilitate the muscle-building process.

Bottom line: While it is possible for women to get bulky, it's highly improbable.

Factors that Affect Muscle Size

The amount of muscle that anyone can put on with weight training depends on three factors: Gender, genetics and training intensity.

Males generally have greater levels of testosterone and growth hormone, which are highly instrumental in the muscle building process. Females, on the other hand, typically lack the level of muscle-building hormones to put on significant muscle mass. There are a small percentage of women that naturally have higher testosterone levels and have the capability to put on mass. Most, however, do not.

Genetics dictate your muscle fiber makeup. Everyone has both slow-twitch and fast-twitch types of skeletal muscle fibers, but vary in the percentage of each type they possess. Slow-twitch muscle fibers, which are smaller, are beneficial for endurance activities because they're designed to perform a high number of low-intensity repetitions over time. Fast-twitch fibers are larger, more explosive and can producer greater amounts of force. Men and women who are genetically predisposed to having more fast-twitch fibers will put on more mass with weight training compared to those that possess predominantly slow-twitch fibers.

Training intensity, or the structure of a weight-training workout, is the only one of the three factors for muscle size that is in a woman's control.

If You're Worried About Getting Bulky

While you now understand that most women simply don't have the capability to become bulky, if you're still concerned with putting on too much muscle mass, you can adjust your training intensity and volume to ensure you don't stimulate growth.

High volume workouts are used to build muscle, so keep your workout volume low by selecting one exercise per muscle group and sticking to just one to two sets of every exercise.

For example, a good workout that hits all the major muscle groups once and yet keeps training volume low is one to two sets each of:

Additionally, keep your load less than 80 percent of your 1 repetition maximum. Your 1 repetition maximum is the highest amount of weight you can perform an exercise for a single repetition. If you think the highest weight you could do one repetition of chest press is 50 pounds, for example, you'll want to keep the weight you use to less than 80 percent of that weight, or 40 pounds.

What Typically Happens when Women Lift Weights

For nearly all women, weight training elicits several benefits without causing bulk. Regular weight training, for example, supports body fat loss. Weight training boosts your metabolic rate for hours after your training session, causing you to burn more calories throughout the rest of the day. Women who are consistent with their workouts will therefore increase their lean muscle and reduce their body fat percentage. Some women may notice a slight increase on the scale, as muscle weighs more than fat, but will still become leaner and notice their clothes hanging loose.

In interest to women in particular, regular weight training builds and maintains bone density. With age, women naturally lose bone and become susceptible to osteoporosis. Osteoporosis is a condition where bones become weak and brittle, and can fracture easily.