Dieting is not a good idea while we're still growing.  

Try encouraging her to participate in a team sport such as netball, football... go along with her, it could be fun! That way she can lose weight, get fitter, and feel good about herself. Exercise speeds up the metabolism, allowing us to eat loads without gaining any weight at all. Taking a bit more exercise is what is recommended for people of all ages, especially if they haven't got help to plan a diet.

If she already takes a lot of exercise, then it is quite likely that she is putting on muscle, and so that is probably why she is worried about her weight: muscle weighs more than fat. She needs to make sure she gets plenty to eat after sport.

People who diet young and secretly tend to become salad freaks, and that means that they get very little protein or oils, which is essential to be healthy, even veggies don't live on salad. 

 REMEMBER -

1.  Crash dieting is bad news. Weight need to be lost gradually.

 2. If she does eat something, don't let her regret what she's eaten. 

Just don't worry, honey. Look out for her and be around, and if you think she's genuine then consider telling someone. At least talk to her about it. Maybe go to your science teacher and ask them if they can re-cap nutrition and calories (you must have tests coming up in the summer. Say you need to revise it!) That could be the jolt she needs. 

If she wont listen try some literature. Try Girls Under Pressure by Jacqueline Wilson and Fat Chance by Jacqueline Roy, ask for it at the library. A shocking dieting novel may be enough to get her eating sensibly. Say she must read it because it's a really good book. Read them yourself too, they may help you come up with some ideas!

You should worry that someone else is becoming anorexic if they:

• Become obsessed with food and cook for others, but don’t eat themselves
• Get very thin
• Seem restless when meals are served up, won’t sit down and eat.
• Mess about with food on their plate and spread it all around instead of eating it
• Leave the table before meals have finished
• Spit the food out somewhere or make themselves sick in the toilet
• Weigh themselves a lot
• Behave very secretively 

You should worry that someone else is becoming bulimic if they:

• Have recurring episodes of bingeing
• Have a lack of control over the binges
• Have a regular use of self-induced vomiting, laxatives, diuretics, strict dieting, fasting, or vigorous exercise to prevent weight gain.
• A minimum average of two binge-eating episodes per week for at least 3 months
• Persistent concern over body shape and weight.

If you think that a friend or family member is anorexic or bulimic, try and talk to them about it. Share your worries with someone else like your parents or a teacher. And keep eating normally yourself – it’s not your fault and you don’t have to blame yourself. You’ve got to be a normal person she or he can trust.

It won’t help the anorexic or bulimic person to get better if you blame them or make them feel guilty, either. Anorexics are already scared and unhappy inside. Keep showing them the affection you always used to.

Website: Eating Disorders Association