You’ve probably heard about BMI. Many people and physicians around the world use it to determine if your weight is normal or not. Many fitness apps also use it to track a person’s fitness level. However, researchers and scientists all over the globe have raised their doubts on BMI’s efficacy to actually determine the true state of health of a person.
This article shows you all you need to know about BMI, its uses, its advantages, and its disadvantages. It also presents other methods that can be used to measure muscle or fat mass.
What Is BMI?
BMI stands Body Mass Index. It is a measure of your body size using your height and weight. The results of such measurement indicate if a person has the right weight, is underweight, overweight, or obese in relation to their height. Thus, is a very simple way to calculate and determine if a person’s weight is within a healthy range.
BMI is a common method of assessing obesity since its calculation requires only height and weight, making it inexpensive and easy. However, keep in mind that BMI is only used as an indicator and is not diagnostic of the exact body fat percentage of an individual. Having a high body mass index can be viewed as a potential health risk but a clinician would need to perform further assessments to evaluate the patient’s state of health.
Health Risks Of Extra Weight
Ensuring that you maintain your weight shouldn’t just be looking better physically. In fact, it’s a very important way of staying healthy. Extra fat in the body puts you in a lot of problematic scenarios healthwise. For example, excess weight can lead to more cholesterol clogging your arteries, which means your heart has to work harder to pump blood throughout your body.
According to multiple research studies, extra unhealthy weight puts you at greater risk of certain diseases like:
- Coronary artery disease
- Type 2 Diabetes
- Gallbladder disease
- Sleep apnea and other respiratory problems
- Cancers, most especially colon cancer.
This is why it is important to screen people routinely to know when they are crossing the threshold between healthy and unhealthy weight. It is helpful to detect obesity early and to start a weight loss program or changing your lifestyle habits before the onset of any disease. As they say, prevention is better than cure.
Calculating your BMI is extremely simple. All you need is your height and weight measurements.
If you’re using imperial units:
BMI = weight (kg) ÷ height² (m²)
If you’re using metric units:
BMI = weight (lbs) ÷ height² (in²) × 703
- This means you divide your weight by your height and multiply that entire value by 703 to convert it to imperial units.
Alternatively, you can always use a BMI chart or an online BMI calculator to check your BMI. For BMI calculators, enter your weight or height in either imperial or metric units and the system will generate your BMI automatically.
On the other hand, when using a BMI chart, locate your height in inches on the side of the chart and look across the chart to find your weight in pounds. Afterward, check if the result corresponds to being of normal weight, overweight, or obese.
BMI Weight Status Categories
The results of BMI measurement are then categorized by weight status. Here are the standard BMI ranges and the relevant weight status categories for adults. In adults, the BMI ranges are not age-specific and apply to both sexes.
- BMI less than 18.5: This indicates that you are underweight and may need to put on some weight. You are recommended to meet your doctor or dietician for advice.
- BMI of 18.5 – 24.9: This indicates that you are at a healthy weight for your height and are advised to maintain this weight.
- BMI of 25-29.9: This indicates that you are slightly overweight. You may be advised to lose some weight for health reasons and see your doctor or dietician for advice.
- BMI above 30: This indicates that you are obese or heavily overweight and at risk of serious health problems. You are advised to meet your dietician or doctor for proper counseling.
- BMI above 35: This indicates you are extremely obese and at high risk of serious health problems. You are advised to meet a health or dietary professional for proper counseling.
Is BMI Truly Accurate?
Most people argue that BMI is enough to check if a person has a healthy weight for their height. However, a lot of clinicians are beginning to question its accuracy and effectiveness, and with good reason.
The original aim of BMI is to estimate the amount of body fat a person carries based on their weight and height and thereby categorize people based on what is appropriate for their size. However, it fails to provide information on actual body composition like the amount of fat, muscle, bone, and other tissues. This is important to note as muscle is heavier than fat so a person with high muscle mass may fall into the “overweight” category even though he/she is actually healthy and very fit.
BMI also doesn’t differentiate between different types of fat, each of which has different metabolic effects on health. BMI doesn’t take into consideration where fat is stored either. For example, visceral fat develops deep among muscles and around organs like the liver. Moreover, it releases certain hormones and other agents that can disrupt the body’s ability to balance its energy needs. Since it’s so deeply embedded in your body, relatively thin people with high levels of visceral fat may be considered healthy and are at no risk by their BMI score.
A study published in PLoS One reported that among the 1400 men who participated in the study, about a quarter of obese men had their weight wrongly diagnosed based on their BMI. Inversely, another quarter who were categorized as obese by BMI were in fact not considered obese based on their overall body fat percentage.
Other Measures Of A Healthy Body
Apart from body mass index, there are other methods that can ascertain your body fat percentage. These methods may be preferred over BMI in cases where the cause of the person’s weight is unsure. They include:
- Waist-hip ratio
- In this method, you first need to measure the natural waistline and the widest part of your hips. It involves dividing the circumference of the waist by the hip circumference measurement and comparing the results with a waist-to-hip ratio results chart.
- Body fat measurement
- Differentiating between muscle and fat when measuring your weight can provide you with a much more accurate assessment of your body composition. Techniques that can help you in doing so include hydrostatic weighing, electrical impedance myography, bioimpedance spectroscopy, and many others.
- Waist circumference measurement
- By measuring your natural waist level, you can get a good indication of the amount of abdominal fat you’re carrying. Men with a waist circumference of 40 inches and above are considered to be at risk.
- Body adiposity index
- This method multiplies your hip circumference by your height.
BMI can be a very useful tool for predicting some health risks that can be caused by excess weight. However, people should be careful when using it as it doesn’t take factors like activity levels and body composition into consideration.
You can always make use of other methods to determine correctly the body’s fat or muscle composition. What’s important is that whatever method you use, your health and your physical well-being are on the right track. Practice healthy eating and lifestyle habits and you’ll not only look fitter but you’ll feel it as well.