Home|Blog | What Does BMI Mean and How Does It Impact My Health?

By Vallari Kothari, MD, Griffin Faculty Physicians Endocrinologist

Body Mass Index (BMI) is a measure of weight in relation to height. It is an inexpensive, easy and practical method to determine if you are underweight, at a healthy weight, overweight, or obese.

BMI is an estimate of body fat and an indicator of your risk for diseases that can occur with more body fat. The higher your BMI, the higher your risk for certain diseases such as type 2 diabetes, high blood pressure, heart disease, stroke, gallstones, high LDL (bad) cholesterol, low HDL (good) cholesterol, sleep apnea & breathing problems, certain cancers (endometrial, breast, colon, kidney, gallbladder, and liver), depression, osteoarthritis, and all-causes of death (mortality).

BMI is calculated by dividing a person’s weight in kilograms by the square of height in meters. BMI = weight (kg) / [height (m) x height (m)].

Click here for an online BMI calculator on the Griffin Bariatrics website (the calculator is located on the right-hand side of the webpage).

Weight Categories

The standard weight categories associated with BMI ranges for adults more than 20 years is:

BMI  Weight categories
<18.5 Underweight
18.5 – 24.9 Healthy weight
25.0 – 29.9 Overweight
30 and above Obese

BMI Categories for Children

BMI for children and teens (2-19 years) is calculated using the same formula as adult BMI but it is interpreted differently. BMI growth charts consider age and sex specific differences and visually show BMI as a percentile ranking.

BMI percentile for age and sex Weight categories
<5th percentile Underweight
5th – 84th percentile Healthy weight
85th – 94th percentile Overweight
95th percentile and above Obese

Limitations of BMI

As weight of an individual is fat mass, plus lean body mass (muscle and bone), the limitation of BMI is that it overestimates body fat in athletes and others who have a muscular build, and underestimates body fat in elderly and others who have lost muscle. With that said, the accuracy of BMI as an indicator of body fatness also appears to be higher in people with higher levels of BMI.

A healthcare provider is able to properly assess and evaluate an individual’s BMI, health status, risks, and recommend how much weight one might need to lose. The good news is that weight loss of even 5-10% of your current weight will help lower your risk of developing diseases associated with obesity. If you are concerned with your weight, BMI, or obesity related diseases like type 2 diabetes, contact your Griffin Faculty Physicians Endocrinologist for an appointment at (203) 735-3500.

2013 AHA/ACC/TOS Guideline for the Management of Overweight and Obesity in Adults.
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Willett, K. et al., 2006. Comparison of bioelectrical impedance and BMI in predicting obesity-related medical conditions. Obes. (Silver Spring), 14(3), pp.480–490.
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