There have been so many articles published over the years saying that BMI is a load of rubbish. Why is that you ask?
We’re going to give you an insight into what the professionals say and what alternative methods are out there that are better than BMI.
The Body Mass Index was created in 1998 by the National Institutes of Health to make sure that doctors, researchers, dietitians and government agencies were on the same page when it came to patients’ weight.
It would show if someone had a healthy weight by dividing their weight in pounds by their height in inches squared, then multiply the results by a conversion factor of 703. Pretty confusing right? It’s a good thing they have the table on Google images for us to look at.
For example, with someone who is 5 feet 5 inches tall (65 inches) and weighs 150 pounds, the calculation would look like this: [150 ÷ (65)2] x 703 = 24.96.
Most health professionals choose BMI as a measurement as it is what they know. It is preferred as it is easy to take down those two figures and put them into an equation. It allows doctors to see if a patient is high, low or no risk when it comes to weight related health problems.
“I think BMI is a very good and easy screening tool,” says obesity expert, Cathy Nonas, MS, RD, a spokeswoman for the American Dietetic Association.
But sometimes easy isn’t always accurate.
BMI doesn’t take into account someone’s age, gender, or muscle mass. You could have someone who is 150 pounds and be overweight as it is mainly fat, and you can have someone who is 150 but looks slim with lots of muscle mass. It leads people to believing they are overweight when they are not. This is the case for a lot of athletes.
Take for example, basketball player Michael Jordan: ”When he was in his prime, his BMI was 27-29, classifying him as overweight, yet his waist size was less than 30,” says Michael Roizen, MD.
Now doctors believe that waist circumference is a better indication of overall health.
“Fat around your waist is more biologically active and can do more damage to your body than weight around your hips,” says Roizen, co-author of You: On a Diet. “The data show that waist circumference is more reliable and more closely correlated with diseases associated with obesity.”
Unlike BMI, you don’t need any math to properly measure your waist. Use a soft tape measure around your bare midsection at your belly button. Find your upper hip bone, and measure around the abdomen above the bone. The tape should be snug, but not dig into your skin.
Another way to do this is to measure your height in inches and half it, your waist should not be more than that number.
Nick Trefethen, Professor of Numerical Analysis at Oxford University’s Mathematical Institute, says BMI leads to confusion and misinformation. He believes that the BMI height2/weight term divides the weight by too much in short people and too little in tall individuals. This means tall people believe they are fatter than they really are, and short people think they are thinner. The confusion sets in.
Nobody has the same body weight or shape. Somebody who is tall can weigh the same as someone who is small, so BMI is not a clear indication of who is overweight and who is not.
Your body is not only affected by excess body fat, but also where it is on your body.
People with an apple shape are at higher risk for health problems as they gain weight in their abdominal region.
If men have a bigger waist circumference than 40 inches, and for women 35, then you are linked with higher risks for type 2 diabetes, high blood pressure, abnormal cholesterol levels and heart disease, when BMI is 25 to 34.9. Your percentage of body fat, waist circumference, BMI and physical activity need to be taken into account for each person when assessing their physical health.
The latest data from the University of Pennsylvania was published in journalScience as showed that BMI doesn’t distinguish between different types of fat, which have different metabolic effects on health. BMI can’t take into account where the fat is stored.
Belly fat, commonly known as visceral fat, is more dangerous than fat that is under the skin and hanging onto your hips. Visceral fat develops deep among the muscles and around the organs such as the liver and disrupt the bodies ability to balance it’s energy needs by releasing certain hormones and agents. Even people who would be considered normal or thin can have high levels of visceral fat.
Of course, BMI isn’t the only way to measure body fat and see if you are healthy. Dr Margaret Ashwell, independent consultant and former science director of the British Nutrition Foundation said:
Keeping your waist circumference to less than half your height can help increase life expectancy for every person in the world.
She says that it should be considered as a screen tool alongside the BMI. On its own BMI doesn’t take into account the distribution of fat around the body.
Some people even use the skin fold thickness test to get a rough idea of body fat percentage. It refers to the measurement of subcutaneous fat located directly beneath the skin by grasping a fold of skin and fat, and measuring it with calipers. Of course this in itself isn’t accurate enough as people distribute fat in different areas of their body.
An extremely expensive way of seeing how much fat you have are CT scans and MRIs as they offer a clearer glimpse by separating out fat from muscle, so those who are athletes won’t be classed as overweight.
Overall, it is pretty clear that BMI doesn’t work for everyone and a little number on a scale should rule no one’s life. Exercise frequently, eat right and you’ll be the best version of you that you can be.
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