BMI: what it is, how to calculate it (and results table)

BMI, or Body Mass Index, is a simple calculation that allows you to assess whether a person is within the weight considered ideal for their height.

BMI is a formula used by several health professionals, including doctors, nutritionists, physical education professionals and nurses, to quickly find out whether a person is at an appropriate weight or whether they need to gain or lose weight.

Although it is a very common tool, BMI is not considered the most accurate way to assess weight, as it does not take body composition into account. Therefore, in the case of athletes (who have a greater amount of muscle mass), it is recommended to use other techniques, such as bioimpedance, for a more accurate assessment of body composition. Understand how bioimpedance is performed.

How to calculate BMI

The BMI calculation is done using the following formula: weight (kg) ÷ (height x height) (m).

But you can also find out if you are within your ideal weight using our online BMI calculator.

What is the normal BMI?

BMI is considered normal when the value is between 18.5 and 24.9 kg/m².

BMI table

The following table indicates the classification of BMI values, according to the World Health Organization:

When you are below your ideal weight, you should increase your calorie and nutrient intake. Those who are overweight should consume fewer calories and practice physical activity to eliminate fat stores, which increase the risk of obesity and heart disease. Find out how many calories you should eat per day to reach your ideal weight.

How to improve the BMI result

When the BMI result is not ideal, there are some precautions that can help achieve the ideal value:

1. What to do to lower BMI

When the BMI is above ideal and the person is not very muscular or an athlete, it is recommended to lose weight. To do this, you must maintain a healthy diet, prioritizing fruits, vegetables, lean proteins and whole grains. See how to go on a diet to lose weight.

To achieve results even faster, it is recommended to exercise to increase calorie expenditure and increase metabolism. Using teas and natural supplements can be an incentive to help you lose weight more quickly and healthily, without having to go hungry. Some examples are hibiscus tea or ginger tea with cinnamon, but a nutritionist can recommend others that are better suited to each person’s needs.

2. How to increase BMI

If the BMI result is below ideal, it is recommended to increase your calorie intake to gain weight and muscle mass. However, you should avoid eating ultra-processed foods, such as pizza, fried foods, hot dogs and hamburgers. Check out how to follow a diet to gain weight and gain muscle mass.

When not to calculate BMI

Although BMI is widely used to check whether a person is overweight or not, this method has some flaws. Therefore, it is recommended that in addition to BMI, other means are used to check whether the person is actually above or below the ideal weight, such as measuring fat folds, for example.

Therefore, BMI is not recommended to assess ideal weight in the following situations:

• Athletes and very muscular people: because it does not take into account the weight of the muscles. In this case, measuring the neck is a better option;
• Elderly: because it does not take into account the natural reduction of muscles at these ages;
• During the pregnancy: because it doesn’t take into account the baby’s growth.

Furthermore, BMI is contraindicated in cases of malnutrition, ascites, edema and in bedridden people.

Therefore, the ideal is to always consult a nutritionist, to personally make all the necessary calculations to assess weight and, if necessary, recommend a personalized eating plan, taking into account each person’s general health status.

Why is it important to be within your ideal weight?

It is important to be within the ideal weight because the right weight is closely linked to the person’s general health status.

Having a small accumulation of fat in the body is important, as fat helps maintain body temperature, acts in the formation of hormones and the absorption of nutrients. Excess body fat accumulates in the liver, waist and inside the arteries, making it difficult for blood to flow and increasing the risk of heart disease.

Therefore, being within the ideal weight is essential to maintain health, prevent the emergence of diseases and improve quality of life.