Weight Loss

Weight Loss: Understanding BMI

What is a good weight for me?

This is the most commonly asked question within weight loss, and has been researched for years. Currently, we follow the guidelines of the the body mass index (BMI) or Quetelet index.

BMI is a value derived from the mass (a word often interchanged with “weight”), and height of a person. The BMI is defined as the body mass divided by the square of the body height, and is universally expressed in units of kg/m², resulting from mass in kilograms and height in meters.

The BMI is an attempt to quantify the amount of tissue mass (muscle, fat, and bone) in an individual, and then categorize that person as underweight, normal weight, overweight, obese, and morbidly obese based on that value.

The BMI can also be represented by the chart below, which displays BMI as a function of mass and height (this time, in pounds and inches) using contour lines or colors for different BMI categories. Note that:

  • The ideal BMI reading for a healthy weight is 18.5 to 24.
  • Being overweight means that you have a BMI score of between 25 and 29.9.
  • A score of 30 and above means that you are obese.
  • A score of 40 and above is considered morbidly, or seriously obese.

All of these categories help predict potential health issues and are calculated at every office visit.

bmi-chart.jpg

Sometimes the scales need to be adjusted slightly for different factors such as people with a lot of muscular weight, large vs. smaller body frames, as well as those in the extreme ends for height. Too often, I hear those with perfectly healthy BMIs claim they’re “too fat”. The BMI guidelines give specific data proving they are not. This can then help me get the focus off body image, and on to ways to improve diet and exercise habits, fostering a better feeling of overall well being and good health.

One study found that an individual’s BMI generally correlated with their body fat percentage, noting that obesity has overtaken smoking as the world’s number one cause of death. Clearly, our weight has a significant impact on our health. Let’s use this information as a starting point on where we stand now, and work towards a viable goal of healthy living.

-Dr. Courtney

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