Im 12, 5'6, and weigh 160, how much weight and how fast can i lose it to look like carrie underwood, lady gaga, ashley tisdale, etc?

Forget Lady Gaga and Carrie Underwood.  If you begin a workout routine tomorrow, something as simple and walking, light jogging, aerobics, power yoga...whatever, they they'll want to look like you!  But, it also takes dieting.  You can work out all you want, but if you're just stuffing your face with chips, Cokes, and Timbits (I am in Canada, it's a donut thing), then you may not even break even in terms of calories lost and gained.  If you can begin to lose a little bit of weight, just a pound  or two a week even, before the end of this school year, you'll be around 30 lbs lighter.  It can be done.

I am teacher in high school and I see girls every day dreaming of looking like Carrie and Lady etc., but these girls can't.  Why?  Because they're not Carries or Ladys!  They are Monicas and Michelles and Werwofs!  We're all different and there's only so much we can do to our bodies, thanks to genetics.

I am 6'0, 180 lbs, which I am happy about.  But my hairline is pointy and I have wrinkles around my eyes since I spend half my days laughing at my two kids.  That's life.  I have learned to deal with the things I can and the things I can't control  At your age, it's tough to have perspective on some things since you're constantly being bombarded with the media telling you to do this or that.  But if there is one thing you can control, it's how you treat your body and this is where exercise and diet comes in.

The benefits of taking care of your body go way deeper than how you look in a pair of jeans.  The emotional benefits will last longer than both of these singer's careers.  I feel sorry for someone like Lady Gaga, cause in ten years when she looks back at her 15 minutes (okay, 15 months or more!) of fame, she'll be begging for that kind of attention again while she's sticking botox in places it doesn't belong and starring in reality TV shows with the likes of Justin Beiber and "The SItuation". 

(sorry, I digressed into teacher mode there for a second)

My point is, living a healthy lifestyle and experiencing the happiness that comes from this, is not influenced by one's fame or by the number of hits they get on Google in  a week.  You'll learn as you mature and begin to broaden your perspectives on life.  I just hope you learn this lesson sooner than later.

Good luck, keep track of your progress, get a workout partner, cut down on the crap that goes in your body, and lose weight cause it'll make your healthier and happier, not because you hope to one day look good in a video with Beyonce and Tyrese.

At 5'6, your ideal weight is between 118 and 148.

If you're looking to attain the kind of body these ladies have, you're going to be aiming for the lower end of this scale.

As far as how fast can you lose the weight...well, a good amount of weight loss to shoot for is 1-2 pounds/week.

The more excess weight you have on you, the easier it will be to lose weight.

So anyways, what you need to start doing is eating fewer calories...just don't drop below 1,200 calories/day, that would be crash dieting and wouldn't be healthy.

Fill yourself up on veggies/salad, eat lean meats and have 1-2 fruits/day with a handful of nuts here and there (not too much, they are calorically dense).

Cut out processed foods as they tend to be calorically dense but not satiating.

Aside from this, start doing cardio and work up to 1 hour/day, that will burn an extra 500 calories/h which will lead to another 1 pound of loss each week.

As far as how long it will take..if you take it at a reasonable rate of 2 pounds/week, 20 weeks...

If you reduce your calories further and do more cardio you could do it faster than that though.

This will provide more info on how to go about all this.