If the sadness is only likely to be short-lived, vigorous exercise can suppress it, at least while you are exercising. Afterwards, the appetite will come back, but if you only have healthy low calorie fruit to snack on you will have burned off more calories during exercise than you consume with the fruit.
Best exercise for for a girl your age dance to whatever music you like that suits the emotional state you want to be in. Here is one I like to dance to when I'm sad because I got angry, and want to worry some aggression out of my system - can't bothered eating when you get down to this - its worth listening to and matching that guy's moves when he gets going. Love it.
Best wishes and cheer up - Majikthise.
Try drinking an herbal tea instead - sweeten with stevia if you want that sugary taste, a s it has no actual sugars in it and won't cause you to crave more carbs. Try to avoid chemical artificial sweeteners which tend to have negative effects on the body.
Gymnema leaf, licorice root and dandelion root teas are all great for preventing food cravings, especially of the sweet variety.
Try doing other things rather then eating. Find out what your hobbies are, then concentrate on that. I know when I'm sad or upset, I intend to have my ipod on and crank up the volume and sing at the top of my voice...Annoys the crap out of the person I'm pi-ssed off with.
Blow bubbles. I know it sounds silly, but it's one thing find to be relaxing and distracting. If you don't have what you need for the bubbles (wand, etc), you could always try going for a walk, talking to a friend, or chewing some sugarless gum.
Get active. Do something to distract yourself and keep your hands busy. Try painting or a craft or something like that or even better get out of the house and go have some fun!
Do something instead that will make you happy like your favorite hobby. That is not eating.
Go for a walk, its a habit to eat when ur sad, everytime ur sad go for a walk
duct tape ur mouth or go on medication, orrrr just dont?
you should try journaling whenever you are sad