The Problem with the BMI Scale Chart

bmi scale chart

Doctors and physical trainers alike have put a lot of focus on BMI over the years. The BMI scale chart was established as a standard form of measurement for an individual’s fat ratio within the health industry.

Excess BMI is associated with poorer health. But the BMI scale chart isn’t perfect. In fact, the method has had several known flaws from its original conception.

Here’s what you need to know about this common form of measurement, and why it should be taken with a huge grain of salt.

What is BMI?

BMI stands for Body Mass Index. It’s a mathematical formula designed to measure body fat based on weight and height.

In order to measure your BMI, you must identify your total weight in kilograms and divide that number by your height in meters. You then compare your BMI to the BMI scale chart in order to estimate your body fat ratio based on what category your number falls under.

There are four categories in total:

  • Underweight: Any score that is below 18.5
  • Normal: Scores between 18.5 and 24.9
  • Overweight: Scores between 25 and 29.9
  • Obese: Any score ranging from 30 and above

For example: if a person’s weight is 65 kilograms and you are 1.6 meters tall, you divide 65 by 1.6 to equal 40.625.

This measurement falls under the range of obese.

But is this person really obese? From a photo, he or she may not look it. In fact, they may appear relatively fit or healthy.

Why the BMI Scale Chart Isn’t Perfect

Even Lambert Adolphe Jacques Quetelet, the creator of the BMI scale chart, stressed the importance of not taking the BMI formula too seriously. He was a mathematician, after all, not a doctor.

BMI was simply a mathematical equation put together for a government survey during the early 19th century in order to gain a relative idea of how much of the population was overweight.

This guesstimation doesn’t take into account many of the key indicators of obesity, such as waistline size and the unique proportions of every individual.

Someone with a high bone density or a significant amount of muscle but a low ratio of fat may find his or herself falling under the BMI chart’s “obese” category simply because their body weight seems high in relation to his or her height.

Likewise, everyone is built differently based on their genetics. Individuals who are tall and lean or short and stocky often find themselves with an inaccurate BMI reading simply because their genetics don’t align with the way the formula works.

Despite the fact that we constantly use the BMI scale chart to measure an individual’s fat ratio, the truth is that the formula is highly inaccurate. It wasn’t even meant to be used for this purpose.

The BMI formula’s creation was specifically designed to measure a rough average of obesity based on a large population. Its accuracy is slightly better in this respect because it depends upon correlations found within a large number of BMI’s instead of a single measurement of one individual.

How to Properly Measure an Individual’s Fat Ratio

So if BMI is inaccurate, how can someone determine whether or not he or she is overweight?

In order to understand one’s weight-to-fat ratio, the individual must identify what part of his or her weight is made up of bone density and muscle rather than fat.

How much bones weigh can vary from one person to another based on height, proportions, and density. Someone with a high bone density will weigh more than someone with low bone density, yet still be the healthier between the two.

Muscle also weighs more than fat, which can tip the scales in a misleading direction. This is why many physical trainers or health coaches advise their clients not to put too much emphasis on weight gain when they’re working out.

You may gain weight while burning fat because your muscle mass is rising. Thus, a better indicator is not the scale, but rather your body’s tone.

Start with Your Waistline

First, measure your waistline with a soft measuring tape. This is the space just above your hip bones. Take a deep breath, exhale, and then measure your waist circumference for an accurate measurement.

Women should aim for a waistline that is 35 inches or below, while men should aim for 40 inches or below.

This is a common practice used by doctors because it provides an accurate measurement of how much abdominal fat a patient has on his or her body. Excess fat in this area can elevate a person’s risk for multiple health concerns, including:

  • Stroke
  • Diabetes
  • Heart Disease

You can purchase a soft measuring tape at your local pharmacy or general goods store.

Measure Your Waist-to-Hip Ratio

Want to dig a little deeper? Measure your waist-to-hip ratio. This method can be used on both men and women and it can reveal a lot about your fat ratio.

This method can be implemented simply by conducting one more measurement in addition to your waistline. Take the soft measuring tape and wrap it around the widest part of your hips.

Once both waist and hip measurements have been gathered, use this calculator to measure the ratio and evaluate the reading.

This ratio should be below 0.9 for most men and below 0.85 for most women. Numbers above these may indicate that the individual is obese.

The String Challenge

For those who have already measured both their waist, there is a third simple test they can implement. It’s called the String Challenge and it’s a credible measurement for identifying whether or not an individual is overweight.

To do this, one simply compares his or her waist circumference to his or her height. If the circumference of the individual’s waist is less than half of his or her height, that person is considered healthy.

Learn How to Live Healthier

The BMI scale chart may not be the most accurate, but it does help us consider our overall health. More specifically, it forces us to question where our health is today and how it compares to where we want to be.

If you’re looking to improve your health, start with these tips on diet and nutrition. Paired with a proper exercise regiment, these lifestyle changes will help you achieve your goals.

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