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What is Good BMI and What Does it Mean?

woman standing on a weight scale

When it comes to bodyweight management, adopting an active lifestyle, coupled with the right choice of diet are excellent contributing factors. Having an ideal bodyweight is a fitness goal most of us want to achieve, but this fitness goal is not achieved overnight, it’s a gradual process that requires hard work and dedication.

How then do you know if you have the ideal bodyweight or how far off you are? That is when BMI comes in.

The question then is, what is BMI, what is good BMI and what does it mean?

We will look at answering the above question and also look at factors to consider when it comes to BMI. Is BMI an accurate measure of health? You should hopefully find an answer to this question too by the end of this blogpost.

What is BMI?

BMI, which stands for Body Mass Index, is a calculation used as a key indicator of overall health by dividing a person’s weight in kilograms by the square of his/her height in metres.

The formula for calculating BMI is therefore as follows: Weight (kg) / [height (m)]²

The resulting figure usually ranges between 16 and 35. Your BMI score helps to determine whether you are underweight, of normal (ideal) weight, overweight or obese.

For adults above the age of 20, BMI scores are interpreted as below:

  • Below 18.5 = Underweight
  • 18.5 – 24.9 = Normal Weight
  • 25 – 29.9 =Overweight

What is Good BMI?

Well, according to the above BMI score ranges and interpretations, having a BMI score between 18.5 and 24.9 means you are considered to be healthy ( a healthy body weight).

Is this then an accurate measure of your overall health? The health experts don’t think so.

This therefore means, other factors must be taken into account, to enables us determine whether an individual’s BMI score is good or not.

To answer the question, ‘what is good BMI’?, the answer is simply, ‘it depends’.

We’ll look into why this is the case later in this blogpost.

blue plate with weight loss enscribed

A Little Background on BMI

BMI was developed in the 19th century and was formerly called the Quetelet index. The name came from its developer, the Belgian Mathematician, Adolphe Quetelet.

BMI was widely adopted as it was very easy to calculate and was used as a tool to measure the risk of health problems associated with bodyweight at population level. In other words, BMI was developed as a risk indicator of disease in a general population.

There are numerous arguments against the reliability of BMI as a health indicator, which we will look at in a bit, but in general, BMI is used to screen the health of the general population due to the correlation between bodyweight and certain health risks.

Some health risks associated with not having a normal BMI are listed below for your perusal:

Health Risks Associated With Being Underweight (BMI < 18.5)

Yes, being underweight does not mean you get to worry less about health problems. A very low BMI, below 18.5, can also be an indicator of underlying health issues. Health risks associated with being underweight include:

  • Nutritional deficiencies.
  • Weakened immune system.
  • For women, a difficulty in conceiving.
  • For women, an irregular menstrual cycle.
  • Depression.
  • Osteoporosis from too little vitamin D and calcium. This is a health condition that weakens bones, making them fragile and more susceptible to breaks.
  • Digestive diseases.
  • Increased risk of complications from surgery.
  • Increased risk of breathing problems.
  • Dry skin.

Health Risks Associated With Being Overweight (BMI > 25)

If you are overweight or obese, and physically inactive, you expose yourself to a number of health issues. In general, the higher your BMI, the higher the risk of developing certain health conditions linked with excess fat and bodyweight.

Health risks associated with being overweight include:

  • Type 2 diabetes.
  • High blood pressure (hypertension).
  • Cardiovascular disease.
  • Some cancers such as breast, colon and prostate cancer.
  • Gallbladder disease.
  • Osteoarthritis. This is the most common form of arthritis. It is also referred to as degenerative joint disease or ‘wear and tear’ arthritis.
  • Sleep and respiratory problems.
  • Some mental health issues including depression.
  • Stroke.
  • Liver disease.
  • High cholesterol and its accompanying health issues.
  • Risk of premature death.

woman performing a squat

Is BMI an Accurate Measure of Overall Health?

Despite BMI’s status as the most popular way of determining a healthy bodyweight, it still comes under a lot of criticisms by many health experts.

According to health experts, BMI is by no means a perfect metric for determining how fit and healthy someone is. As BMI calculations are based on only height and weight, the resulting figure with its accompanying interpretation can be very flawed and inaccurate, and therefore not an accurate marker of individual health. Why is this so?

The answer lies in the various factors not considered when calculating BMI. In order to get a well-rounded and accurate picture of how healthy someone is, so many factors need to be taken into consideration. Your level of fitness or health goes way beyond just a measure of your weight and height, and the ratio of their combination.

When calculating BMI, the following factors are not considered:

  • Body composition and body fat distribution. For example, athletes and bodybuilders tend to be muscular, resulting in them having high BMIs. This is because muscle mass weighs more than fat, meaning, based on BMI calculations, an athlete could be seen as overweight or obese and considered unhealthy. This BMI interpretation then becomes inaccurate as the high BMI is due to a high muscle mass. BMI simply can’t differentiate between muscle mass and fat mass. BMI therefore tends to overestimate the health risks for adults with a high muscle mass and underestimate the health risks for adults with a low muscle mass.
  • When it comes to fat distribution, two individuals with the same BMI will be seen as being of the same level of health, when in fact, one of them might be pretty worse off than the other. According to health experts, fat predominantly deposited around the buttocks and hips doesn’t appear to pose the same health risks as having fat around the abdomen, regardless of bodyweight. In other words, more concern should be placed on how fat is distributed in the body than how heavy you are.
  • Ethnic background. Research has shown that at any given BMI, Asians have more body fat than people of European descent, while blacks generally tend to have low body fat than those of European descent. This means that, using the same BMI range for all ethnic groups will result in either an overestimation or an underestimation of health risks associated with either a lower-than-normal or higher-than-normal BMI.

woman measuring waist size

What is The Way Forward?

As shown by health experts, BMI on its own is not a perfect measure of health. It is however still a useful tool to be considered in addition to other health data to get a near-accurate picture of health.

When it comes to having the ideal body weight, being healthy goes beyond just having a good BMI. While working towards a healthy body weight, it’s more important to pay attention to your waist size. Being obese by waist circumference increases the risk of cardiovascular disease irrespective of your BMI.

Regardless of where you fall on the weight scale, focusing on healthy habits such as maintaining an active lifestyle, eating healthy and getting quality sleep should be of prime importance.

Speak to your healthcare provider if you are concerned about your weight and body composition. Always stay safe.

a plate of salad

Do you have any question, contribution, correction or comment? Please feel free to leave them in the comments section below.

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Daniel

2 Comments

  1. I checked my BMI about a month ago and it says am overweight but I don’t look like someone who is overweight. What do I do?

    • Thanks for the comment Lydia. Yes, you might actually be overweight without actually looking it. The distribution of your body fat and muscle mass could have an effect on whether you appear overweight or not. The key point is to maintain a healthy weight for your height by training regularly and eating healthy.

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