What is BMI in adults, children, and teens
Body mass index (BMI) measures the size of the body. It is calculated by dividing the weight of a person by the square of their height in meters. Experts term BMI as an indicator of the total body fat/high body fatness of an individual. Medical experts use BMI to screen for the various weight categories, and can indicate whether a person is overweight, health weight or overweight/obesity. Typically if your BMI is outside a healthy range it significantly increases the risk of diseases
If you have too much weight, you are at risk of diseases like type 2 diabetes, cardiovascular conditions, and hypertension. On the other hand, too low weight can lead to malnutrition, osteoporosis, and anemia. So, you must maintain your weight within a healthy range.
Keep in mind that BMI doesn’t measure body fat directly, and neither does it account for age, ethnicity, sex, or muscle mass in adults. BMI uses standard weight status categories that can help doctors track their weight status and identify potential health issues in individuals.
The calculation of BMI uses mathematical formulas. However, you can also estimate your BMI using tables that can match your height in inches to weight in pounds. You can conveniently calculate your BMI using the calculators found on the internet.
BMI is indicated in numbers. According to the world health organization, people (adults) having a BMI of between 25 and 29.9 are considered to be overweight, a BMI of 30 and higher indicates obesity. At the same time, a BMI of below 18.5 is an indication of being underweight. Healthy people usually have a BMI ranging between 18.5 and 24.9 a healthy weight.
A typical BMI formula is:
BMI = weight in kilogram (kg) ÷ height in meter squared (m2)
A BMI chart also can give details concerning a person’s weight – underweight, normal, overweight, or obese.
|Body Mass Index (BMI)||Weight Status|
|18.5 – 24.9||Normal|
|25.0 – 29.9||Overweight|
BMI in adults
As earlier indicated, calculating the BMI involves using the height and bodyweight to determine whether a person has a healthy weight not. You can measure BMI using the following methods.
BMI in metric units is achieved using the following method
BMI = kg/m2
If you measure your height in centimeters must first convert the measurement into meters by dividing it by 100.
The imperial formula can also give you the BMI. The formula is:
BMI = lbs x 703/in2
The formula means multiplying an individual’s weight in pounds by the value 703 and then divide the value you get by the individual’s height in square inches.
- BMI calculator
The calculator is the easiest way to get your BMI value easily. People who do not like calculations can easily find their BMI using these calculators.
Metric BMI Calculator: To use this calculator, you enter the height in meters and weight in kg.
Imperial BMI Calculator: this formula uses height in feet/inches and weight in pounds or stones.
- BMI charts
There are numerous types of calculators to measure BMI. You can download such charts online, locate your height in inches which are situated on the sides, then across, and identify your weight in pounds. At the top scan to see if the results correspond to weight.
Understanding BMI results
BMI of less than 18.5
If you have A BMI of less than 18.5, you are underweight. In this case, you must add some weight to stay healthy. However, you need to consult your doctor or a dietician for advice on the feeding program.
BMI of 18.5–24.9
If your BMI is between 18.5 and 24.9, it indicates that you have a healthy weight for your height. If you maintain a healthy weight, you definitely lower the risk of developing health problems like type 2 diabetes.
BMI of 25–29.9
A BMI of 25-29.9 is an indication that you are slightly overweight. Your healthcare provider may advise you to lose some weight for health reasons. Keep in touch with your doctor or a dietician for further advice.
BMI of over 30
Having a BMI of over 30 is an indication that you are approaching obesity, or you are heavily overweight. This means that if you do not lose weight, you are at risk of getting diseases. Again, talk to your doctor or dietician for advice on losing weight.
BMI in children and teenagers
BMI in children is quite different from adults because boys and girls develop at different rates. Similarly, they have varying amounts of body fats at different ages. Thus, while measuring BMI in children, you need to put age and sex into consideration, unlike in adults.
Medical experts (doctors and other healthcare providers) do not use weight and height into consideration because:
- Children grow/change monthly
- Female and male boy types vary at different rates
- Weight changes with height
Nevertheless, doctors usually calculate BMI for children and teens in a similar fashion to adults, i.e., measuring height and weight, and then locating the BMI number and age on the sex-specific BMI for age chart.
Calculator and charts for BMI in children and teens
Currently, one of the reliable sources of BMI charts is produced by the Centres for Disease Control and Prevention (CDC). These charts also provide the corresponding BMI-for-age percentile for children and teens.
Clinical relevance of BMI
BMI is usually an indicator of health risk in individuals as it indicates the total body fat in individuals. Healthcare providers screen for overweight as well as obese individuals. A higher BMI may put an individual in the risk of getting high blood cholesterol or other lipid disorders, type 2 diabetes, stroke, high blood pressure, gallbladder disease, heart disease, sleep pane and snoring, premature death, certain cancers, and osteoarthritis and joint disease.
Keep in mind that BMI is not accurate enough to be used as a diagnostic tool, but can screen potential weight problems. Factors that doctors may consider include:
- The thickness of skinfold – indicates how much fat is in the body
- Assessment of diet and physical activity
- Evaluating family history of cardiovascular conditions and other related conditions
- Recommend additional necessary health screening
Other points that doctors may look at include cholesterol level, blood sugar level, gender, waist circumference, menopause status, and smoking status.
After these assessments, the doctor then will get a clear picture of your condition, and they can recommend the right diet and exercise regimen for you to keep healthy.
In children and teens, bearing extra weight increases the risk of a wide range of health conditions mentioned above. According to the American heart association, children having a higher BMI have a higher risk of developing asthma, psychological stress, and low self-esteem.
Is BMI an accurate measure?
Most people find BMI to give an accurate measure of obesity. Keep in mind that BMI doesn’t provide a more accurate picture of the composition of the body like muscle, fat, bone as well as other tissues.
However, in some people, BMI is a more accurate measure in some people than others. For instance, extremely muscular people may be categorized as overweight, whereas they are very fit and healthy. People with a meager body fat percentage could have the same BMI score to someone who I overweight.
Another tricky category of people is the frail and elderly individuals who may have a healthy weight when they have a little muscle mass and a higher percentage of body fats. For children and adolescents with the following status must be carefully evaluated and interpreted with care.
- Those still growing
- Those with large body frames/petite builds
- Pregnant women
- Highly muscled individuals
As much as many people may rely on BMI, put in mind that there are some exceptions. A good example is an athlete with massive muscle who has a high BMI than the very active individual but does not mean they are unhealthy. So you can combine BMI with other measures to get an accurate result.
These other measures include waist-hip ratio, waist-to-height ratio, and body composition. This method measures the fat in the body and the lean body mass. Typically, the system focuses on the amount of fat and its distribution around the body. If carefully assessed and combined with BMI measures, you can get a more accurate picture of your health status.
Benefits of a healthy weight
Healthy weight is essential for many reasons as it reduces the odds of developing health conditions. Still, it comes with an additional benefit like
- Reduced joint and muscle pains
- Increased levels of energy
- Improved sleep patterns
- Improved blood pressure
- Improved heart functioning and well-functioning circulatory system
- Improved regulation of the fluids of the body