Originally Posted by Autumn Leaves If I start lifting 5 lb weights will it make my arms bigger? or does that only happen to men?
Ditto to making sure to eat enough calories. Building muscle requires energy, not just protein.
That said, if you intend on building muscle, you might want to focus on two things:
2) Mass of the weight and ammount of repetitions
First, you might want to get a book on weight lifting, or check one out from the library. I recommend anything from the Gold's Gym series. Ideally, if you can afford it, go to a professional trainer, even is just once.
Basically, if you have bad form, you are likely to injure yourself, or more commonly, get absolutely no results.
After focusing on form, you can start thinking about the mass you lift, and how many times you do it. 5lb weights are really close to nothing if you are using any large or medium muscle group. If you lots of reps (upwards of 20), you will "tone" up, but not nessesarily build more muscle. What you might need to do is to use different weights for different muscle groups. Use the 5lbs for shoulders. Use 15lbs for back, pecs, legs, etc.
The basic idea is that with large mass and low reps, you build muscle. With low mass and lots of reps you maintain tone.
But you can read this all for yourself, or even better, talk to a personal trainer. I hope this helps.