Just some advice from your friendly, neighborhood fitness instructor:
When an "authority" says high-repetition, low-weight exercise is the key to reducing body size, I am pretty sure that they didn't envision a 175 lb. female doing outer-thigh lifts with 10-lb. weights 45 times. To clarify, they most likely meant 15-20 repetitions at a weight where you are exerting considerable effort by the 13th to 15th rep. (Note: If you can carry on a normal conversation at the 13th rep, then you need more weight.)
Think about it this way: how many times have you lifted a fork to your mouth? And has it built any muscles? EXACTLY! Later.