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What’s a Healthy BMI – and Why It Matters

October 18, 2021

Maybe you’ve gained a few pounds recently or have been battling extra weight for years. Body mass index (BMI), an easy-to-use screening tool, can help you understand what lifestyle changes you need to make to get healthier.

The BMI chart is a tool doctors use to determine if a person is at a healthy weight relative to their height. The BMI chart helps determine a patient’s risk for certain obesity-related diseases, and bariatric surgeons use the chart to qualify patients for weight-loss surgery. 

Who Developed the BMI Chart? 

In the 1830s, a Belgian mathematician and sociologist developed the BMI formula to provide a simple way to measure the nutritional status and overall health of the general population. The formula divides a person’s weight in kilograms by their height in meters, squared.  

So, BMI = weight (kg)/height (m)2  -- or you can use an online calculator.

The National Institutes of Health (NIH) began using the BMI to define what constitutes “obesity” in 1985, and it has since been widely used as a health marker to determine whether a person is at a healthy weight.

The BMI chart categories are:

●      18.49 or below = underweight

●      18.5-24.9 = normal weight

●      25-29.9 = overweight

●      30 or more = obese

●      40 or more = morbidly obese

How Your Doctor Uses the BMI Chart 

Since BMI is an estimate of body fat, it is a way to gauge your risk of disease that can occur with more body fat. The higher your BMI, the higher your risk for developing certain health conditions, such as heart disease, diabetes, respiratory and sleep problems, and certain cancers. 

Bariatric surgeons use the BMI chart to help determine if a person is a candidate for bariatric surgery, and what kind of surgical intervention may be best. They also consider your overall health status.  

For example, if you have a BMI of 30, along with other weight-related health concerns, your doctor will likely recommend lifestyle changes to help with weight loss, rather than bariatric surgery.  

If you have a BMI of 40 along with weight-related health concerns, such as sleep apnea, diabetes and/or high blood pressure, you are more likely to be a candidate for bariatric surgery. Most bariatric surgeons likely will not recommend bariatric surgery unless you have a BMI of 40 or over. 

Other Ways To Measure Body Mass 

BMI does not always accurately measure body fat percentage or the overall health of a person. For example, a weightlifter may be at a healthy weight, but because muscle is denser than fat, their BMI may be classified as “obese” when their body fat percentage is actually quite low. That’s why BMI isn’t the only tool healthcare professionals use to analyze your health and risk of developing diseases. 

To determine if your BMI is a health risk, your doctor will perform additional assessments, including: 

●      Waist circumference measurements

●      Waist-to-hip ratio

●      Diet evaluation

●      Review of family history

●      Relative fat mass, which predicts body fat mass by measuring height and waist

●      Skinfold measurement, which uses a device called a caliper to pinch the skin and fat to estimate body fat percentage

●      Body adiposity index, which multiplies your hip circumference by your height

The Benefits of Reducing Your BMI 

Research shows that reducing your BMI by even a few points can lower the risk of diseases associated with obesity. Maintaining a healthy weight is important for your overall health and well-being, and it helps reduce the risk of many health conditions. 

If your BMI is in the overweight or obese categories, lifestyle changes can help you lose weight and reduce your BMI. These include: 

●  Eating a healthy diet rich in proteins, fruits, and vegetables

●  Reducing your intake of processed foods

●  Getting daily exercise for at least 15 to 20 minutes

●  Getting seven to nine hours of sleep every night. 

Making these changes can not only help lower your BMI and improve your health but will also help you feel better and give you more energy to enjoy life.

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