While on a weight lifting program, the right hormones (testosterone) are necessary in order to bulk up. Women's testosterone levels are much lower than men's, so in most cases, they are not capable of building large muscles. In fact, since muscle takes up less room than fat, women tend to lose inches when they strength train. So in addition to the physical benefits (increased metabolism, decreased risk of osteoporosis, increased strength), strength training will help you slim down too! Women, in fact, are more likely to tone up from strength training rather than bulk up. Research shows that women can add up to 30% lean muscle and end up looking thinner, feeling stronger and being firmer.
Our society and pop culture seem to associate weight training with oversized muscles, but that's just one avenue, which is extremely difficult for most people (including men) to achieve.
Women with an intense fear of becoming large as a result of weight training are at a disadvantage when it comes to their health. The problem most women run into isn't building too much muscle, but not building enough. This sets them up for increased risk of osteoporosis later in life, as well as a reduction in muscle mass of about 2-5% per year, which has an adverse affect on metabolism (and can result in weight gain).
So don't be afraid of those weights, ladies! You're adding lean muscle, building stronger bones, increasing strength, and speeding up that metabolism.
