One point of discussion we often get with clients is that "yes I want to get stronger but I don't want to get big muscles". If we look at the back at our biology lessons from high school we see that women are predominately estrogen, and a small amount of testosterone (the hormone responsible for possibly gaining muscle mass), and men are mostly testosterone and a small amount of estrogen.
For women and their hormone makeup it is really not possible to develop muscle mass. As for men, we can develop some muscle mass, but we are still limited by our genetics. Meaning, most men don't possess the genetics to gain much muscle mass. For both women and men, it really is a muscle density issue. As muscle is added to the body, it shows up as greater muscle density.
The main message of gaining muscle, it takes up less volume on your body than the same amount of fat. If you were able to do a straight trade of 5 lbs of muscle for 5 lbs of fat, you would fit into your clothes much better. Google fat vs. muscle to see the images.
This chart shows how you can fit into your clothes with more muscle.
Woman A – 5’8” – 150lbs
Body Composition 20% fat
30lbs of fat
120 lbs of lean wgt
Dress size 8
Woman B – 5’8” – 150lbs
Body Composition 30% fat
45 lbs of fat
105 lbs of lean wgt
Dress size 12
This woman has 15 lbs more muscle and still fitting into smaller size clothes.