Your BMI should be between 18.5 and 24.5 to be in the healthy range. according to your height, you should weigh between 92 and 120 lbs

cant be done. you cannot target weight loss, the ONLY way is to lose weight overall, which yes you are correct, intense cardio.
jogging. biking. jumproping are great.

a bike will give you excellent cardio with no joint pressure (unlike jumping rope & running, which are extremely hard on the body)

once you have a good cardio routine and are losing weight, the next best thing you can do is change your diet. I am not sure exactly of the merit of this claim but it worked great for me, i took all sugar & alot of processed foods out of my diet and my stomach is very flat, without needing to do crunches regularly. and no BS ladies, by eliminating sugar i have also seen my cellulite disappear.

you will still have to incorporate ab & lower back as well as oblique exercises for definition & tone. but you can do stomach exercises all day & you wont see the muscle until you lose the overlying fat.

It varies by person, but for me it was 15%. Don’t eat junk. It’s not just about calories. Eat protein, fruits, veggies, dairy, whole grains, and take vitamins. Your body has to be healthy in order to be ready to reproduce. A baby won’t grow in an environment that doesn’t provide optimal nutrients, and your body requires fat in order to prepare for the metabolic demands of breastfeeding (that’s what periods are for from an evolutionary perspective…having kids). Many olympic athletes don’t start until age 16 or older due to their lack of body fat and a routine of rigorous exercise.

Should you be worried? Unless you want to get pregnant before age 16, you might as well enjoy it. Your body will catch up at some point.

Good luck.

Don’t worry, your time will come.
Please stay away from too much junk food.
Eats foods high in protein, calcium and iron.
This will help you have less painful cramps.
Please look at link below for more information
Take care..

sit ups and crunches may or may not build muscle, but you must do the correctly if you’re going to do them at all
building muscle means that you burn more calories at resting rate
but careful, the average human body loses muscle twice as fast as it builds it.
I think you’re really looking for cardio though
cardio, aerobics, and anaerobic excersizes burn off calories and fat fastest of all excersizes
It’s all about getting your heart rate up to the right zone, and keeping it there.
You can find a heart chart on this link to show you where you need to keep your heart rate up to in order to burn whatever fat you have for your age.
Your way of eating is also a BIG BIG factor
try to avoid saturaded and trans fats
monounsaturated and polyunsaturated fats are the good stuff
if a nutrition label says there are 4g of fat (for example) but does not show the fat under “saturated” or “trans”, they’re the good kind of fats.
Goodluck!

p.s. – don’t get your heartrate higher than the chart reccomends, and start out easy on yourself – it can be very dangerous if you do not listen to your body.

You need to eat properly – and eat *more*… a minimum of 2000 calories per day.

“A 59-inch tall, 77-pound, 13-year-old girl has a body mass index (BMI) of 15.6, which is at the 7th percentile for age. Although being thin could be perfectly normal for this girl, she could potentially be at risk of being underweight, particularly if she has recently lost weight or has stopped gaining weight. A healthy weight range for this particular girl would be from about 81-pounds to 111-pounds.”

Considering that you’re much more muscular than most people might be at your weight, I’d say you’re at least 12 to 15 pounds underweight, and it’s no *wonder* you don’t menstruate (assuming you’ve even matured enough to be menstruating, that is).