I wanted ask how can I lose wieght in a week because I am only 13 years old and wear 270 pounds. How can I lose weight that I can keep off?

Losing 10 pounds in a week would be very unhealthy. You should only lose 1-2 pounds per week.

You should eat foods low in fat and high in protein. Exercise daily. Count your calories and find out how many calories you should eat to maintain your weight. Then subtract about 300-500 calories from that number and try and eat that amount of calories every day. Also drink a lot of water.

Calorie Counter Database - Free Online Diet Program (http://caloriecount.about.com) is a good place to start.

You need a lifestyle change not crash diet.

Do what snippy07 said to do