Research indicates it’s correlated with the well-regarded standard methods in measuring body fat.* In fact, it is believed that BMI plays a role as an indicator for many other medical issues, putting individuals with certain scores at a higher risk for health complications.
Regardless, it is valuable for weight management and health planning. BMI is calculated by dividing your weight by your height, squared… Incredibly, this inexpensive and simple indicator has been connected to metabolic and disease outcomes that greatly influence wellbeing. This easy-to-perform screening established the weight categories: underweight, normal, healthy, overweight and obese.
A normal BMI score is one that falls between 18.5 and 24.9.
- 18 or lower: underweight.
- 18.5 to 24.9: normal, healthy weight.
- 25 to 29.9: overweight.
- 30 or higher: obese.
BMI isn’t a perfect tool. It is an aggregate method of measuring body fat (population based). Muscles and bones have greater densities. It is possible that an athlete or muscular person has a high BMI and a low level of fat. The majority of people would not call themselves athletes, therefore, BMI is a very good gauge for most.
Why use it?
BMI correlates with the measure of total body fat and is therefore an indicator of health risk. It is frequently reported along with other factors such as a family history of diseases, blood sugar levels, cholesterol levels, blood pressure and more. Weight loss is only one of many reasons to take BMI into account. If your score is high, you run the risk of various conditions, such as:
- High blood cholesterol or other lipid disorders.
- Type 2 diabetes.
- Heart disease.
- Stroke.
- High blood pressure.
- Certain cancers.
- Gallbladder disease.
- Sleep apnea and snoring.
- Premature death.
- Osteoarthritis and joint disease.
BMI has been associated with cancer. A study by London-based physician, Dr. Krishnan Bhaskaran studied 5.24 million people, 166,955 of whom developed cancers. This large and complex study concluded that adult BMI was connected with 17 types of the 22 cancers found. The study was funded by The National Institute for Health Research, Wellcome Trust, and the Medical Research Council.
“When it comes to cancer risk, it’s important to know your BMI,” says Ann-Marie Hedberg, associate director of Clinical Nutrition at MD Anderson. “For some cancers there is a correlation between a high BMI and an increased risk.”
Additionally, companies that manage risk take BMI into consideration. Most life insurance companies ask for an individual’s height and weight in the application questionnaire. A score today can help determine your health in 20 years. Taking the result into consideration and adjusting your physical activity and diet can be of great benefit.
Who is it for?
It’s not for everyone. Some people have less accurate results from BMI, when used as an indicator. If an individual is built and has bulging muscles, they might fall into the “overweight” category. A person with low body fat can therefore be given a similar score as someone who is obese. Inversely, an elderly and brittle individual might be in a normal category even though they are actually underweight. Factors such as skin firmness and general mass could skew the results if the mass is due to exercise or overeating. The test sometimes cannot tell the difference.
- Women tend to have more body fat than men.
- Certain cultures have different ranges of healthy BMI.
- People who are older tend to have more body fat than younger adults.
- Athletes have less body fat than non-athletes.
All in all, it is best to use every tool at your disposal when it comes to your health. Alternatively, body fat can be measured using skinfold thickness measurements, bioelectrical impedance, dual-energy x-ray absorptiometry, and isotope dilution. These methods are far more complex and not always available.
When in doubt, talk to your doctor, if you have a high (or low) BMI. Meeting with a professional can help you determine if you have underlying health problems. For example, sudden weight gain may be associated with thyroid problems. By reading about these topics, you are already on your way to better health. Keep up a clean and balanced lifestyle maintaining a healthy weight, avoid stress and enjoy life. Calculate what it takes to be happy and move forward.
For a fast and easy calculation, visit the BMI calculator from the U.S. Department of Health & Human Services, click here.
SOURCES:
- *How useful is body mass index for comparison of body fatness across age, sex, and ethnic groups? Am J Epidemiol. 1996; 143:228-39.
- **U.S. Preventive Services Task Force. Ann Intern Med. 2003; 139:930-2.
- ***https://www.cdc.gov/obesity/data/adult.html
