What is BMI?

The BMI is a simple medical screening tool that measures the ratio of your height to your weight to estimate the amount of body fat you have. Your healthcare provider can calculate your BMI by using your weight in kilograms (kg) divided by the square of your height in meters (m²). Don't worry if you're not sure about your BMI, it's a quick and easy way to get an idea of whether you're at a healthy weight.


We all know that feeling when we're carrying a few extra pounds. But how can you tell if you're actually living with obesity?



Most of us can relate to the idea that a high BMI usually correlates to body fat — the higher your number, the more body fat you may have. However, it's not quite that straightforward! There are some cases where it's less accurate. BMI is just one piece of the puzzle when it comes to your overall health. Healthcare providers use tools like BMI and other tests to get a good understanding of your health status and any risks you might be facing.


Why is BMI Important?

BMI provides a valuable tool for healthcare professionals, enabling the diagnosis of weight types and the screening of certain health conditions. It is essential to be aware of the risk factors associated with low and high BMI figures. Individuals with a BMI below 18.5 (classified as underweight) may be at an elevated risk for developing the following conditions: 

  • Infertility 
  • Malnutrition 
  • Anemia 
  • Osteoporosis 
  • A weakened immune system may result in an increased susceptibility to infections and illnesses.


If your weight is below the healthy range, the healthcare professional will probably request specific tests to evaluate your overall health and determine if you are malnourished. 


On the other side, as your BMI goes up, so does your risk for these conditions:

  • High blood pressure 
  • Sleep Apnea 
  • Heart disease 
  • Diabetes (Type 2)
  • Osteoarthritis (Joint Disease)
  • Gallstones (stones formation in the gallbladder) 
  • Some types of cancer, including colon, breast, endometrial, and gallbladder.
  • Mental health issues like depression.


It's important to keep in mind that you could have any of the health conditions listed above and not have a high BMI. In the same way, you could have a high BMI and not have any of these conditions. Genetics and other factors, such as cigarette smoking, play a large role in the development of these conditions.


How to Calculate Your BMI?

To help you figure out your own BMI! All you need is two things: your weight and height. Then, follow these simple steps:

  • Multiply your height (in meters) by itself.
  • Divide your weight (in Kg) by the number you got in the first step.



Let's say, for instance, that we have an adult who is 1.79 meters tall and weighs 83 kilograms. Their BMI is calculated like the following: 


83(1.79)(1.79) = 25.9 


For most adults, if your BMI is:

  • below 18.5 – you're in the underweight range
  • 18.5 to 24.9 – you're in the healthy weight range
  • 25 to 29.9 – you're in the overweight range
  • 30 to 39.9 – you're in the obese range
  • 40 or above – you're in the severely obese range


What is a Healthy BMI?

A range of 18.5 to 24.9 is considered optimal for a healthy BMI. 


It's so important to remember that there's more to your overall health than just body fatness. Lots of other things can affect your health, like your genes, how active you are, whether you smoke or use tobacco, how much alcohol you drink, and even your mental health. All of these things can impact your overall health and your likelihood of developing certain medical conditions.


Are there any Limitations for BMI?

While BMI can be used for most individuals, it is not without limitations. It is therefore crucial to avoid placing undue emphasis on this metric.


The limitations of using BMI to diagnose weight types

  • The Body Mass Index (BMI) does not differentiate between lean body mass (i.e., the weight of all body tissues except fat) and fat mass. It is therefore possible for a person to have a high BMI (due to muscularity) but a very low-fat mass, or vice versa.


  • The BMI chart is applied consistently to adults assigned male at birth (AMAB) and adults assigned female at birth (AFAB), despite the fact that AFAB individuals typically have a higher body fat percentage than their AMAB counterparts.


  • The standard BMI chart has not been adjusted for the increasing average height for adults over the years.


The standard BMI chart isn't the best way to assess body fat for the following populations.

  • Athletes and bodybuilders
  • Children and teenagers
  • Seniors aged 65 and above
  • People with muscle atrophy (wasting) because of medical conditions




The limitations of using BMI as a screening tool for health conditions


While the BMI is an effective screening tool for identifying individuals at risk of developing certain health conditions, such as Type 2 diabetes and heart disease, its limitations should be acknowledged. These include:

  • It is worth noting that the BMI does not provide information about the location or distribution of body fat. This is an important consideration because excess fat accumulation in certain areas of the body, such as the abdomen, is associated with a higher risk of health conditions than excess fat accumulation in other areas of the body, such as the thighs.


  • It's not always clear that the link between BMI and death rate takes into account other factors like a family history of diabetes, high blood pressure, heart disease, and high cholesterol. It's also worth noting that family longevity (average lifespan) and family history of cancer can play a role.


How to Maintain a Healthy BMI?

  • Eat a well-balanced diet. A balanced, calorie-controlled diet is the ticket to a healthy BMI - the safest way. You're more likely to steadily reach a healthy BMI and keep the extra weight off by making simple, healthier food swaps, reducing portion sizes, and cutting back on high-calorie foods and beverages.


  • Keep an eye out for hidden sugar. Consuming more sugar than is recommended can present a significant challenge to achieving or maintaining a healthy BMI. When attempting to lose weight, many individuals choose to reduce their consumption of sweet treats and carbonated beverages. However, it is often the case that sugar is present in a number of unexpected food items. Examples include: Pasta sauces, Granola and cereal bars, and Ketchup. 


  • Exercise regularly. It is well documented that increased physical activity can contribute to a reduction in (BMI) in a healthy manner. Medical professionals worldwide recommend that individuals engage in a minimum of 150 minutes of moderate-intensity exercise per week, or 75 minutes of vigorous-intensity exercise. You should combine cardio and strength training to enhance muscle strength and improve weight loss outcomes.


  • Monitor your weight. Maintaining a healthy weight can help lower your risk for serious health conditions such as type 2 diabetes, heart disease, and high blood pressure. Eating a mix of healthy foods and being physically active can help you manage your weight - and it has a lot of other health benefits as well!


  • Keep hydrated. Researchers have found an association between high levels of obesity (high BMI) and poor hydration habits in some individuals. People who are obese are more likely to be underhydrated, and vice versa. The odds of being obese were 1.59 times higher for those who were inadequately hydrated compared to those who were hydrated NIH. 


Are there alternatives to BMI?

  • Waist-to-hip ratio: calculating your waist-to-hip ratio (WHR) is one way your doctor can determine if being overweight is putting your health at risk. It determines how much fat is stored around your waist, hips, and buttocks. The WHR measures the ratio of your waist circumference to your hip circumference, as opposed to your body mass index (BMI), which measures the ratio of your weight to your height. According to the World Health Organization (WHO), a moderate WHR is


0.9 or less for men

0.85 or less for women


  • Body Fat Percentage: because a BMI calculation is based solely on your height and weight, being female or male has no bearing on how this number is calculated. However, there are differences between men and women when it comes to body fat percentage ranges. Age is another factor that affects a person's ideal body fat percentage.


  • Waist circumference: is an indication of whether you are at higher risk for type 2 diabetes, high blood pressure, high cholesterol, and heart disease. All you need is a tape measure and put it at the top of your hip bone, then bring it all the way around your body. A global standard for a healthy waist size is


89 cm or less for women

101 cm for men


The bottom line

According to the WHO, nearly three million people around the world die each year as a result of being overweight or obese. In addition, regardless of any particular medical condition, people with a high BMI often report that they feel better, both physically and mentally, once they have lost the excess weight.


By itself, BMI is not the perfect health indicator. But it's still a useful starting point for important conditions that are more likely to occur when a person is overweight or obese. Therefore, it is a good idea to have an understanding of your BMI and its limitations.