Does Your BMI Really Matter?

First things first, what exactly is BMI?

BMI stands for ‘Body Mass Index’, a measurement widely used to ascertain whether you’re in a healthy weight range. The measurement was first created in the 1800s by a Belgian mathematician and by the late 1900s had been adopted by governments worldwide as a common predictor of health. Your BMI is your weight in kilograms divided by your height in metres squared; a BMI between 18.5 and 24.9 is considered normal. 

What’s the latest?

Research suggests the formula is flawed – BMI may not be the perfect measure of health we once thought. A recent study concluded that tens of millions of people who had overweight and obese BMI scores were, in fact, perfectly healthy. The research also revealed 30% of people with ‘healthy’ BMIs were in fact quite the opposite, based on other health data.

So, what’s going on?

As GP Lucy Hooper explains, “Many scientists believe BMI to be a quick and dirty method. It can be a useful tool for screening larger sections of the population but it doesn’t show the whole story and has real flaws.” The issue, she says, comes down to BMI’s inability to distinguish between fat and muscle. 

Is it true muscle weighs more than fat?

Actually, this one is a myth. As Nutritional Therapist Rebecca Pilkington explains, “One kilogram of muscle and fat will weigh the same, but the difference is in the density. Muscle is much more compact and therefore visually looks different on the body. If someone is working out and eating well, they will lose fat mass and gain muscle mass – this is often why people can look very different but may not see this reflected on the scales.” It also explains why someone with a high muscle mass and very low fat percentage could be classed as obese using the BMI calculation.

So can you be healthy with a higher BMI?

“Absolutely,” says Lucy. “Usain Bolt is a great example of a super-fit athlete who has a BMI that puts him in the overweight range. Equally some people with a low BMI may be a healthy weight for them.”

If the formula is flawed, what’s the alternative?

Rebecca believes there are far more effective measures to determine overall health, the main one being waist to hip ratio. “This ratio, in my opinion, is far superior to BMI. It assesses visceral fat that accumulates in the abdominal cavity and around the internal organs, including the liver, heart, pancreas and kidneys. We’ve all heard the term ‘skinny fat’ and this really can help to give us deeper insight to what’s going on in the body. It’s all about the deep-seated fat that doesn’t show in the mirror.” Lucy also believes there’s value in measuring an individual’s grip strength – she says it’s been shown to be a better predictor of dying from heart disease than high blood pressure. Interestingly, grip strength measures muscular strength, something the BMI calculation totally ignores. 

The bottom line?

There’s more to your health than the number on the scales. In a world where health is the new wealth, it seems somewhat archaic to use something so arbitrary as BMI to determine overall health. Don’t stress about your BMI too much – indicators of strength, fitness and central fat tissue are far more indicative of your health. 

To book an appointment with Rebecca Pilkington, click here; for more information on Dr Lucy Hooper and Coyne Medical click here.