Although it's not a perfect method, body mass index uses a person's weight and height to estimate the amount of body fat he carries. The resulting number classifies each person as underweight, normal, overweight or obese. If you fall into one of the latter two categories, take measures to bring your BMI down into the normal range by losing weight.
Finding Your BMI
A simple formula can help you determine your BMI -- according to the Centers for Disease Control and Prevention, your BMI is calculated by dividing weight in pounds by height in inches squared and then multiplying by a conversion factor of 703. But you can also use a number of BMI calculators available online to do the math for you. Whether you're a man or a woman, if the resulting number is less than 18.5, you're underweight. If it's between 18.5 and 24.9, your BMI is normal, and if it's from 25 to 29.9, you're overweight. A BMI of 30 or more indicates obesity. Your BMI should not be considered the end-all, be-all of your fitness level -- it doesn't take muscle mass into account; therefore, a muscular person, such as an athlete, could be considered obese by BMI standards but actually be perfectly healthy.
Basics of Lowering Your BMI
Lowering your BMI requires losing weight. To do that, you need to burn more calories than you eat, says University of Michigan's University Health Service. To lose 1 pound per week, you need to either eliminate 3,500 calories, whether it's by burning the calories through exercise or eating fewer calories in your diet. This averages out to about 500 calories a day. The amount of weight loss it takes to lower your BMI to the normal range varies based on your height; however, a 5-foot-6-inch person who weighs 180 pounds and has a BMI of 29 -- making him overweight but not obese -- would have to lose approximately 26 pounds to achieve a BMI of 24.9.
Focusing on Your Diet
Your diet plays a significant role in losing weight and, therefore, lowering your BMI. University of Michigan recommends keeping a food and diary to track your caloric intake, ensuring that you're significantly reducing the number of calories you eat per day. Plan your meals and snacks ahead of time so you're never caught hungry unexpectedly, which can lead you to make poor food decisions. Limit the amount of alcohol and sugary beverages that you drink, focusing on getting your calories from nutritious, whole foods rather than the empty calories that soda, alcohol and junk foods provide. To ensure you're not overeating, learn what a proper serving size entails, and measure out your food before you eat it.
Dedicate Time to Exercise
Everyone can benefit from getting a little more physically active, but if you're aiming to lower your BMI, you should dedicate time daily to exercise. According to Harvard School of Public Health, 30 minutes a day is the minimum amount required for weight loss, but only if you're really careful about what you're eating. If you're less stringent about your diet, you need to exercise more and at a higher intensity to lose weight. Examples of moderate exercise include brisk walking, recreational swimming, doubles tennis, biking on level terrain or lifting weight. Vigorous exercise options include jogging or running, swimming laps, single tennis and biking on hills. To burn even more calories, boost the amount of activity in your everyday life -- for example, spend more time cleaning your house, pace when you're on the telephone or get up and talk to your co-worker on the other side of the office rather than shooting him an email. If you're severely overweight or obese, or you've been sedentary for a significant period of time, create a plan with your doctor to ensure your health and safety.
- Centers for Disease Control and Prevention: About BMI for Adults
- University of Michigan University Health Service: Weight Reduction
- University of Rochester Medical Center: Everyday Ways to Lose Weight
- Harvard School of Public Health: Exercise and Weight Control
- University of Rochester Medical Center: How Intense Is Your Workout?
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