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Are you a healthy weight? Use a BMI calculator to find out

Published Date
Author Providence Health Team

The needle on a scale will tell you if you indulged during the holidays. But can it sound an alarm if the extra pounds you packed on pose a health risk?

Unfortunately, it can’t. The best way to assess whether you’re overweight or obese, as well as the associated health risks, is by crunching the numbers in a body mass index, or BMI, calculator.

“For most people, the BMI is a reliable marker,” says Michael Shannon, M.D., endocrinologist with Providence Medical Group in Lacey, Wash. “It’s a good place to start.”

How does BMI work?

Your BMI is calculated by taking your weight and dividing it by the square of your height times 703. (Weight ÷ height in inches ÷ height in inches again × 703.) Not good at math? Use this BMI calculator instead.

BMI weight category ranges for adults are defined as: underweight, normal, overweight and obese. A BMI greater than 25 typically indicates that you are overweight; a BMI greater than 30 indicates that you are obese.

BMI is interpreted differently for children, however. If you want to know your child’s weight category, use this BMI calculator designed for children.

BMI does not diagnose body fat percentage or your health. However, it’s a fast and inexpensive way to determine where you fall in the weight categories, and the health risks associated with those categories.

Optional tests

There are a number of factors that can influence your BMI. For example, an athlete may have a higher BMI because of lean body mass, the amount of weight you carry on your body that isn’t fat.

Bone density and body type can also influence the outcome of BMI. But more often, says Dr. Shannon, a higher BMI is associated with body fat.

For patients who require or want more detailed information, Dr. Shannon uses body calipers, a tool that measures body fat under the skin. Some people go even further by getting water displacement tests, or a DEXA (Dual-Energy X-Ray Absorptiometry) scan. A DEXA scan takes a reading of bone mineral density, lean body mass and fat mass.

“It’s usually competitive athletes who pursue those types of tests,” says Dr. Shannon.

Your BMI is high? Take the next step

If the BMI calculator places you in the overweight or obese range, don’t panic and don’t judge yourself. Talk to your health care provider about what that means for your health and then consider making changes to your diet and lifestyle.

The newly updated Dietary Guidelines for Americans is a great place to start. Here are a few suggestions to inspire you:

  • Serve smaller amounts at home, and share entrées in restaurants. (Or use smaller plates when dishing up at home.)
  • Eat foods that deliver more nutrition and fewer calories. We’ve written a number of posts related to nutrition and weight loss. You might find this post about protein helpful.
  • Get at least 150 minutes of moderate-intensity aerobic activity each week. For kids 6 and older, the recommendation is to get at least 60 minutes of physical activity every day.
  • Sit less, move more. Limit screen time – on TVs, computers and video games – to an hour or two per day.

Providence has facts, tips and experts who can help you lose weight and manage it. Start your research here.

You probably know that taking weight off is easier than putting it on. We recently posted an article on this subject. The post includes some helpful tips on ways to help keep you focused on your weight-loss goal.

Underweight isn’t ideal, either

Although we’ve focused on high BMI, being underweight can be a health risk, as well. Older adults, in particular, are encouraged to maintain a healthy weight as they age. If you’re BMI is below 18.5 or you’re involuntarily losing weight (or know someone who is) talk to your health care provider.

Resources to help you reach your goals

Peruse the Providence Health Library where you’ll find a number of pages on weight management.

The CDC has tips, resources and information about losing weight and keeping it off in its Losing Weight section.

We encourage you to talk with your health care provider about your weight and health concerns. If you don’t have a provider, you can find a Providence provider here.