Understanding Your BMI

Exactly what is BMI? BMI represents body mass index. It converts the person’s height and weight to a single number to estimate the amount of body fat and whether the person is healthy or not. While it has its benefits, it’s definitely not the final say on your state of health or whether you need to lose weight. For instance, a muscular person might not need to lose weight, but the BMI would indicate he or she does. It doesn’t take into effect bone density or overall body composition.

How does BMI work?

A person weighing 150 pounds may be overweight, or they might be the perfect weight or even underweight. It depends on the person’s body frame, whether they’re muscular, and their gender. Yet BMI doesn’t consider these things. It simply is a chart with weight across the top and height down the side. You find your weight and then go down the side to find your height and there’s a number given that ranges from 12 to 50 in the box where they intersect. If that number is below 18.5, you’re underweight. If it’s between 18.5 and 24.9, you’re normal. Between 25 and 29.9 you’re considered overweight and 30 and above you’re obese.

Your bone structure plays a role and that’s just one flaw.

Men have larger bone structure than women, which adds a few pounds more. Men are more muscular and whether you’re a man or woman, the more muscular you are, the more you weigh. Muscle tissue weighs more than fat tissue does, so a cubic inch of muscle will weigh more. The more muscular you are the thinner you’ll look. A person will look thinner if they’re muscular than someone who weighs the same and is the same height who has far less muscle tissue.

BMI isn’t the end all health predictor, just a place to start.

Insurance companies use these charts to identify healthy risks, so do doctors. There have been fit muscular athletes rated and given higher premiums based on BMI until the agent or client sent a photo of them or had a doctor or nurse evaluate their build. It’s just a quick indicator, but not the only indicator. It requires further assessment, such as waist circumference, to identify whether the person is at risk for type 2 diabetes, heart disease, sleep apnea and more issues often faced by people who have a higher BMI.

  • Other ways to measure body mass index include MRI scans and underwater weighing. While those are more valid at identifying body density, fat and volume, they’re also more expensive and take longer.
  • Waist circumference has become a valid indicator of potential health issues. While a male with a 40-inch waist or a woman with a 34-inch waist may still have a good BMI, their chances of developing diabetes are greater.
  • The more muscular you are, the more deceiving your BMI is. That’s also true about people who have very little muscle mass. It’s one of the biggest flaws in using BMI.
  • Newer shortcut techniques are being used that indicate your overall health better. RFM— relative fat mass index is one of those. It is a formula using height to waist measurement. For women use 76 – (20 x height/waist circumference) and for men use the formula 64 – (20 x height/waist circumference).

For more information, contact us today at Next Level Fitness

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