Body Mass Index (BMI): Calculating the ideal weight for your height

Most people are curious about what their ideal weight should be and depend upon various random suggestions by family or friends to determine their weight goals. However, because various factors play a role, there is no one-size-fits-all healthy weight for everyone. What may be the ideal weight for one person might be overweight or underweight for somebody else. This is because your age, height, muscle-fat ratio, sex, and body fat distribution influence what your ideal weight should be.

Your weight is not just important for cosmetic reasons, it also reflects your overall health status and influences your long-term wellbeing. Being underweight or overweight increases your chances of various physical & mental illnesses and hence must be corrected on a priority basis. Being overweight or obese raises your chance of developing a variety of medical disorders, including heart disease, type 2 diabetes, high blood pressure, osteoarthritis, and cancer, whereas being underweight might be a sign of malnutrition, prolonged stress, anxiety, and may lead to anaemia, deficiency diseases & hormonal disorders.

So what should be the ideal weight for you?

Well, scientifically speaking, the ideal way to determine whether you have healthy body weight or not is by correlating your weight with your height. This is best done by calculating your Body Mass Index ( BMI).

What is BMI?

The body mass index (BMI) is a measure of your nutritional & health status calculated by using a formula based on your height and weight. BMI is defined as "a person's weight in kilograms divided by the square of their height in meters," as per the Centers for Disease Control and Prevention (CDC) and WHO.

It is a simple and objective way of determining weight categories such as underweight, ideal weight, overweight, and obesity. Once someone understands their BMI, they can use the standard weight categories to determine which category they fit in and thus assess their risk of developing diseases like Hypertension, Diabetes, Heart diseases, cancers, etc. It is also important to remember that the BMI ranges differ slightly in the Asian population as compared to their western counterparts. The following are the BMI ranges:

Benefits of BMI

BMI serves as a suitable tool to standardize & compare the ideal body weight for people. So if you are wondering whether you are overweight/underweight or the correct recommended weight, BMI is a reliable parameter for you

• It can be easily calculated at home using just a scale and tape.
• The cost of measuring is low.
• It has a direct link to body fat percentage.
• Finally, research indicates that there is a strong correlation between BMI and health. This means that BMI can be used reliably to predict & prevent various diseases and health problems in a person. It gives a fair estimate of your recommended weight for height and is widely used to assess your chances of developing many lifestyle diseases. For eg. People whose BMI falls in the category of overweight or obese, have a higher chance of developing High blood pressure, Diabetes, Cardiovascular diseases, etc. Similarly, people having a very low BMI are technically underweight and may have problems like anaemia, deficiency diseases, anxiety disorders, etc.

Drawbacks of BMI

So BMI is such a simple tool that it can be used by anybody to assess their health status but wait! Like all things in life, BMI, inspite of being a very useful tool, has a few drawbacks too. Well, nobody said Life is perfect, did they? So, we have a few situations in which using only BMI may not be a completely accurate method for assessing the health status of a person.

• BMI does not differentiate between the weight that comes from muscle, fat, and bone. As a result, a muscular person's BMI may be the same as an overweight person but that will not imply that the muscular person is at an unhealthy weight for his/her height. Athletes, on average, have less body fat than non-athletes with the same BMI and may be considered healthy even though the BMI may be in the overweight category.
• As people become older, the proportion of muscle, fat, and bone in their bodies varies, especially in women. For example, an older person will often have more fat than a younger person with the same BMI. So even though your BMI may remain the same over the years, your body fat content may actually be increasing, thus increasing your chances of lifestyle-related diseases.
• Women often have greater body fat than males with the same BMI.
• BMI does not consider the fat distribution across the body. Research has shown that people who have more belly fat are at a higher risk of lifestyle diseases & hormonal disorders as compared to others. Using only BMI as an indicator will give a false sense of assurance to people in whom the body fat is concentrated more around the belly & waist and will delay the corrective measures.
• Pregnant women: BMI is not reliable for them because a woman's body composition changes throughout pregnancy and nursing.
• Children and elderly: A lower BMI is associated with people who have less muscle mass, such as kids who have not completed their growth or the elderly who are losing muscle mass.

So, how does one calculate the BMI for children?

Even though the BMI for children is calculated using the same formula as adult BMI, BMI for children and teens is interpreted differently. Because the amount of body fat varies with age and differs between girls and boys, the BMI of children and teenagers must be age and gender-specific.

The BMI of children and young people (2-19 years of age) is stated as a "percentile." Essentially speaking, the “percentile” indicates where the child’s weight stands in a graph of a large number of children of the same age & gender. Hence, for children, it is a comparative score. The following is the BMI interpretation for children:

Are there alternatives to BMI?

So if BMI is not sufficient to predict the long-term risk of lifestyle diseases, we need to look into other methods for assessing our weight status & health condition. Fortunately, there are other methods that give a more accurate assessment of the fat distribution & health risks. Suppose you believe your BMI does not adequately reflect whether you are overweight or obese. In that case, you can get a more accurate assessment by measuring your abdominal circumference, waist-hip, or waist-height ratio.

• Waist circumference

Waist circumference is a form of measurement that correlates the size of your waist to your health risks. This is a reflection of the fat distribution around your belly region , which has been found to play a very important role in increasing the risk of various lifestyle diseases & hormonal disorders. For both men and women, there are pre-determined limits:
- Men: waist size at 37 inches (94 cm).
- Women: waist size at 32 inches (80 cm).

If your waist circumference exceeds either of these values, you're more likely to get diseases such as diabetes, metabolic syndrome, heart disease, or stroke.

• Waist-hip ratio

Start by measuring your waist at its narrowest point, then your hips at their widest position to get your waist to hip ratio. Allow the tape to lie softly on your skin rather than pulling it tight. The waist size is then divided by the hip measurement.
- A waist-to-hip ratio of more than 0.85 is linked to a higher-than-average risk of diseases in women.
- A waist-to-hip ratio of more than 1.00 in men is linked with a higher-than-average risk.

For more detail on me, the asurement of waist & hip circumference, watch our video on Maitri Youtube channel.

• waist-height ratio

For this, measure your waist circumference and divide it by your height. Both the measurements should be either in cm or inches (the same unit to be used for both).

- In men, a waist to height ratio of 0.53 or more indicates whole-body obesity.
- In women, a waist to height ratio of 0.54 or more indicates whole-body obesity.

Final Takeaway

There are various methods by which one can assess their ideal weight, such as BMI, waist-to-hip ratio, and waist-to-height ratio. However, combining them may be the most accurate technique to determine whether or not you should take action to change your lifestyle to prevent long-term health risks.

Consult with a medical doctor or dietitian if you are concerned about your body weight, waist size, or body composition. They'll be able to provide you with advice on what solutions are best for you.