Getting Fit: What You Need to Know About BMI & Body Fat

Getting Fit: What You Need to Know About BMI & Body Fat

March 21st, 2018 by

If you've been trying to lose weight, get healthier, or just got a checkup from your doctor recently then you've probably heard about BMI or Body Mass Index. And like most people, you've probably heard that BMI is directly connected to how healthy and fit you are. But exactly what is BMI and how accurate is it in measuring the state of your body?

The Truth About BMI

BMI is essentially a ratio of your height and weight (your body mass divided by the square of your body height). This ratio determines whether your weight is proportional to your height: whether you are underweight, normal weight, overweight or obese. Pretty straightforward, right? This means that the more your weight increases disproportionately to your height, the more likely you are to be overweight.

Take note that we said 'more likely' and not always. That is because BMI doesn't really take into consideration which part of your weight comes from muscle and all your other organs, and which comes from fat. It only assumes that any extra weight you have is likely to have come from fat, but as experienced bodybuilders will tell you, this is not always the case.

Your BMI is not actually directly correlated to your body fat percentage. It only considers your height and weight—so whether you're 2m and 100 kg of muscle or 2m and 100 kg of fat, you get the same BMI even though one is considerably fitter than the other.

What You Should be Looking at

While BMI is useful in most cases for gauging your overall health and fitness, it can be insufficient when you consider the actual amount of fat in your body. It's a good gauge for those who are just starting weight loss programs because it at least gives you an idea of whether or not you're on the right track. In some cases however, you just might be losing muscle along with the fat, and you certainly don't want that.

If you're looking to lose fat and not muscle, get fitter and healthier, then you should really be taking a look at your body fat percentage.

Measuring Body Fat

So how do you measure body fat percentage?

Unlike calculating your BMI, measuring body fat percentage is not as easy as getting your height and weight. There are several ways to measure body fat, with varying costs and levels of accuracy:

Body fat calipers – These are relatively cheap tools that you can use to measure your own body fat. They're quite easy to use and are surprisingly accurate considering how affordable they are.

Body measurements – You can take measurements of your body, enter them and have them calculated through online calculators, but these aren't very precise as they only take a few points of data.

The Bod Pod – This is an Air Displacement Plethysmograph (ADP) that uses whole body densitometry to determine body composition (fat vs. lean). It is extremely accurate but can be quite pricey.

DEXA scan - Dual-energy X-ray absorptiometry or DEXA is considered the most accurate method for measuring body fat percentage. It takes a full dual X-ray of your body composition and takes only about 10 minutes, but can be quite costly.

Your Ideal Body Fat Percentage

Now that you know how to measure body fat percentage, you next question is no doubt, ‘well, what is my ideal body fat percentage?’ and the answer is, well it depends.

Generally, for women an acceptable body fat percentage is 25-31% and for men it’s 18-25%. If you want a really lean, fit look however, generally women should aim for 21-24% and men 14-17%. For athletes with that really ‘ripped’ or ‘toned’ look, percentages can go down to 14-20% for women and 2-4% for men.

These are all good ideals to aim for, but remember that every body is built differently and you may have a different body preference than what these percentages dictate. In the end, it all depends on how you’d like your body to look like and of course, how fit and healthy you’d like to be.

AuthorJasmine Green