What is BMI?

Body Mass Index (BMI) is a numerical value derived from a person's weight and height. It is used to classify individuals into different categories: underweight, normal weight, overweight, or obese. The formula for BMI is as follows:

• BMI=weight (kg)/height (m)2

The BMI number can then be compared to established categories to determine if an individual is at a healthy weight. The World Health Organization (WHO) defines these categories as follows:

• Underweight: BMI below 18.5
• Normal weight: BMI between 18.5 and 24.9
• Overweight: BMI between 25 and 29.9
• Obese: BMI 30 and above

How to calculate BMI

Calculating BMI is a straightforward process once you know your height and weight. Here’s a step-by-step guide to calculating BMI manually:

• First, measure your weight in kilograms and your height in meters.
• Use the BMI formula
• Divide your weight (kg) by the square of your height (m²)
• Once you have the resulting number, use the BMI chart to understand what it means in terms of health risk

For example, if a person weighs 70 kg and is 1.75 meters tall, their BMI calculation would be:

• BMI=70/ (1.75)2=70/3.06≈22.9

With a BMI of 22.9, this individual would fall into the "normal weight" category.

Why is it necessary to know the BMI?

• BMI is a standardized measure recognized by health organizations around the world, making it an important tool for international health assessments and comparisons.
• One of the main benefits of BMI is how easy it is to calculate. With just two basic measurements—height and weight—anyone can determine their BMI without the need for special equipment or training.
• BMI provides a quick, accessible screening tool to assess weight and health status.

What BMI does not include?

• BMI does not distinguish between fat and muscle. As a result, muscular individuals, such as athletes, may have a high BMI but low body fat, potentially classifying them as overweight or obese when they are actually healthy.
• BMI does not account for where fat is distributed on the body. Research shows that central obesity, or fat stored around the abdomen, is more dangerous than fat stored elsewhere. Two individuals with the same BMI can have very different health risks depending on how their fat is distributed.
• BMI does not take into account age, gender, or ethnicity. For instance, older adults often have more body fat for the same BMI than younger people, and women generally have more body fat than men. Different ethnic groups may have varying health risks at the same BMI levels.
• BMI does not consider other important factors such as muscle mass, bone density, or metabolic health. For example, a person with a normal BMI could still have metabolic syndrome if they have a poor diet or a sedentary lifestyle.

Interpreting BMI results

• Once your BMI is calculated, understanding its implications is important. While BMI offers an easy way to screen for potential weight problems, it’s essential to recognize that it is not a perfect indicator. If your BMI falls outside the normal range, it may be helpful to consult with a doctor who can offer a more detailed assessment based on your overall health, lifestyle, and other factors.
• In general :

  Less than 18.5

  Underweight

  This can indicate malnutrition or an underlying health condition that requires attention.

  18.5 - 24.9

  Normal Weight

  This range is considered healthy for most people.

  25 - 29.9

  Over Weight

  People in this range may be at increased risk of health problems like heart disease and diabetes.

  More than 30

  Obesity

  A BMI in this range suggests a higher risk for serious health issues and should prompt discussions about weight management and lifestyle changes.