The Body Mass Index - or BMI - is an algorithm of weight and height that was created by insurance companies many decades ago to help determine a person's risk for disease or mortality.
Fast forward to the present day and it's commonly used as a measure of health - but it shouldn't be. From a fitness perspective, this simply doesn't make sense because it doesn't factor in muscle mass or bone density. A person who is lean and muscular but has big bones could have a very high BMI. And on the flip side, someone with a healthy BMI can be 'skinny fat' and unhealthy. (Here's a detailed article about its shortcomings, if you're interested in more detail.)
So if the BMI isn't reliable, what IS a good measure?
If we were to choose one metric, it would be body fat percentage, which is the percent of fat you have in relation to your overall body weight.
Trouble is, it takes more than a simple mathematical equation to figure out. We measure client using a tool designed for this exact purpose called a 'fat caliper'. It measures fat in millimeters at various sites of the body. We choose three to eight sites, depending on how specific the client wants to get. We gently pinch the this area to gather what's called the subcutaneous tissue, and use caliper to measure it (see example photo below).
Based on a formula, we’re able to calculate their body fat percentage using these numbers and several other factors including age, body type, gender, and activity level.
In addition to giving a more accurate overall reading, it's a great way to track fat loss in particular areas of the body.
Body Types (aka Somatotypes)
Which body type you have is another important thing to understand. It can help you measure your success (as it changes), but most importantly, you can use to determine what's possible for you, and the best way to get there.
There are three main body types:
Most people are a combination of at least two types. It's not always easy to tell what you are, especially if you're a combo. A professional can figure this out using metrics such as wrist and ankle size, limb length, height, how easily you put on (and take off) extra weight, etc.
If it's not possible for you to be assessed by a professional - or simply if you're curious! - here's a pretty good calculator, which uses a series of questions to determine your body type. (It got mine right to a T).
So why is it important to understand your body type? Because it helps dictate what's possible for your body, and how to get there. Genetics play a huge role here - you'll always have the bone frame, natural athletic ability, and natural resting metabolism you were born with - but you can do a lot to healthily manipulate your body type.
In other words, you can't change your blueprint, but you can move the dial towards another category once you understand your pre-dispositions, by tailoring your workouts and your nutrition accordingly.
So forget the BMI and focus on your body fat percentage and type. If you're ready for a smart, healthy, and strategic fitness plan - and to figure out your body fat and type - contact us today to book your free consultation (we do these measurements in that meeting). We look forward to helping you move the dial!
Poul Nielsen is the owner and operator of Nielsen Fitness, Toronto's leading team of in-home personal trainers. He has 18 years' experience in the fitness industry and has taught courses in Fitness and Lifestyle Management at George Brown College.
In addition to exercise (obviously), he loves spending time with his family, playing the guitar, strong coffee - and dark chocolate!