October 22nd, 2010
10:12 AM ET
Every weekday, a CNNHealth expert doctor answers a viewer question. On Friday, it's Dr. Melina Jampolis, a physician nutrition specialist.
Question asked by Jenna of Michigan
I'm 16 years old, 5 foot, and 125 pounds. I would like to lose 15 pounds in one month. Is this possible?
Hi Jenna – While it is possible to lose 15 pounds in one month, I would not recommend it for you for several reasons. First of all, at 16 years old you are in the midst of an important period for growth and bone development, and losing weight too quickly (more than 1-2 pounds per week), could result in bone loss which could affect bone density in adulthood.
Secondly, losing weight too quickly when you don’t have a significant amount of weight to lose can result in muscle loss as well as fat loss, which can decrease your metabolism and make it more difficult to maintain your weight loss. Finally, in order to lose 15 pounds in 30 days, at your height, weight and age, you would need to reach a 1750 calorie deficit every day. Here is the math:
1 pound of fat = 3500 calories
3500 calories x 15 pounds = 52,500 calories (total caloric deficit to lose 15 pounds)
52,500 / 30 days = 1750 calorie deficit per day
This means that you would have to eat 1750 calories fewer, burn 1750 calories more per day, or a combination of calorie reduction and exercise.
To give you an example of what it would take to burn 1750 calories per day for someone your size, you would need to jog for 4 hours per day at a pace of 5 miles per hour and as you lost weight and got more fit, you would have to increase this amount slightly as you burn fewer calories the less that you weigh and the fitter that you are. Assuming that you are moderately active, your total daily calorie needs are only about 2000 calories, so cutting 1750 calories would be virtually impossible and unsafe.
I recommend aiming for a healthy, 1-2 pound weight loss per week and make sure to include plenty of low fat or fat free dairy, lean protein and exercise to prevent bone and muscle loss.
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