I received this request the other asking to do a post about this topic and I thought it was a really good question and one that is really needing to be squashed.
Here is the question:
"I was at the gym yesterday and overheard two ladies in a discussion about using 5lb weights for bicep curls.One didn't want to go over 5 because she felt it would bulk her up the other said 8 was her limit.I use 15's.
I'm under the impression that women don't bulk up like men and it'd take a heck of a lot more than a 15 lb weight to get some big guns on a girl.
Could you do a post about it?"
This is why this type of question needs to be squashed forever so read closely and then spread the word to women everywhere.
Unless you are one of maybe less than 1% of the women population who produces larger amounts of testosterone than normal you won't build bulky muscles by using heavier weights.
This is a theory, myth, mis-nomer or whatever you want to call it that have never been proven in the majority of women.
By using heavier weights and increasing the intensity at which you work out builds lean muscle, increases your metabolism and most importantly burns more fat.
I have trained hundreds of women and all we did was heavier weights and high intensity strength interval training and never did one of them bulk up.
They built lean muscle and shed a lot of bodyfat which had them looking great.
So to recap and summarize.
If you want to maximize the burning of bodyfat and permanently increase the speed of your metabolism then don't use the wimpy 3 and 5 pound dumbells or do 20 reps or more.
Choose heavier weights, complete lower reps and increase the overall intensity and speed of your workout to maximize the calories burned.