You need to burn off a total of 35,000 extra calories to lose 10 pounds of fat. This means you will have to burn off more than you eat by creating a caloric deficit. The maximum you should try to safely lose in a week is 2 pounds, meaning you could be at your target weight in about six weeks. Write down everything you eat, including snacks, to find out exactly how much you are consuming per day, and keep track of your physical activity.
Creating the Caloric Deficit
How many calories your body needs depends on your age and gender as well as physical activity levels. Generally speaking, you will want to decrease your calorie intake daily by 500 calories to lose 10 pounds in 10 weeks, or approximately 830 calories to lose 10 pounds in six weeks. Another factor that may affect this is your basal metabolic rate, or BMR, which is the rate your body burns calories when it is at rest. You can use an online BMR calculator to find this number. Always check with your doctor before beginning any type of diet program.
Your daily calorie deficit can come from a combination of diet and exercise; for example, eating 500 calories less per day and burning 250 calories through exercise. If you weigh 155 pounds, you can burn off about 300 calories in an hour of walking at 3.5 miles per hour, or in 30 minutes of biking at 12 mph or swimming the backstroke.