• Sunshine Coast Rehabilitation & Exercise Physiology

Muscle Vs Fat - How Accurate is your BMI?

When looking at fitness superstars such as Dwayne Johnson or John Cena, it can be hard to believe that, medically speaking, they're considered obese. This is due to the Body Mass Index (BMI) system, a tool used in a wide range of health fields that utilises a person's height, gender and age to calculate their ideal weight and then compares this to their actual weight. However, health professionals continually ridicule the system due to its inability to consider the reason behind a person's weight.



BMI Scale

The BMI scale is a chart that ranges from underweight to obese and has numerical values correlating to each weight group.


The groups are as follows; >18.5 is underweight, 18.5 - 25 is considered healthy, 25 - 29.9 is overweight, 30 -35 is obesity 1st degree, 35 - 40 is obesity 2nd degree, and >40 is obesity 3rd degree. For example, a female who has a height of 165 cm and weighs 65kg has a BMI of 23.9, which is considered healthy.

What is Muscle?

The main culprit of an inaccurate BMI reading is the fact that it does not take into account muscle mass as opposed to fat mass. Specifically, this is the case for Dwayne Johnson and John Cena, whose BMIs are 34 and 33 respectively, putting them in the obese category. Of course, these two are very healthy, and are not actually obese. The fact is that muscle is very dense, so it's easy to gain weight when building muscle, which can make your BMI skyrocket, however, this isn't necessarily bad for your health. People with more muscle are reported to have faster metabolism's, increased strength, balance and stamina, better support for joints, and on average live longer. In comparison, fat is a lot worse for your health.


What is Fat?

Fat is a storage of energy for the body, yet when someone eats high calorie foods and doesn't use the energy, it can stay in the body and pile up. While a little bit of fatty tissue is good for us to protect our vital organs, it's when fat starts to get stockpiled that the health issues can roll in. These can include coronary heart disease, type 2 diabetes, high cholesterol, hypertension (high blood pressure), sleep apnoea, an increased risk of blood clots (which can lead to heart attacks and strokes), decreased mobility, chronic pain, and a shorter lifespan.



At the end of the day, it can be hard to manage your health, especially to the advice of online BMI calculators. Here at SCREP, we strive to help you be the healthiest you can be, and are happy to help you on your journey. Be sure to contact SCREP if you want an in-depth health evaluation and plan.

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