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Keep an eye on your BMI

BMI information, limitation and calculation

Body mass index (BMI) has been around since the 1830s when astronomer, mathematician, statistician, and sociologist Adolphe Quetelet formulated the mathematical equation from which BMI is derived. Since then, it has been used by doctors, researchers, personal trainers, and others in their work. Why is BMI useful, what are its limitations, and what can you do to improve yours? Let's find out.

Why is it useful to calculate your BMI?

Body Mass Index (BMI) is a simple formula that estimates your body fat based on height and weight. 1 It’s a useful screening tool that can help to identify people at risk of type 2 diabetes or heart disease. Based on your BMI, clinicians may recommend further testing or evaluation for health conditions related to excess body fat. It’s often used in public health research to track obesity trends. 2 For example, according to statistical reports, from 1999–2000 through 2017–March 2020, the prevalence of obesity in the US increased from 30.5% to 41.9%. 3

For individuals trying to lose weight or improve their health, monitoring changes in BMI can be a useful motivational tool. If you want to determine your BMI, use our BMI calculator. This feature is available only in the US and Canada at the moment. 

Your BMI will fit into 1 of 5 bands:

  • under 18.5 – described as underweight
  • between 18.5 and 24.9 – described as the “healthy range”
  • between 25 and 29.9 – described as overweight
  • between 30 and 39.9 – described as obesity
  • 40 or over – described as severe obesity

What are the limitations of BMI?

BMI has several flaws that make it an imperfect measure of body fat: 

  • BMI does not differentiate between muscle, bone, fat, and water. So it can give misleading results for people with a high muscle mass. If you’re an athlete or a bodybuilder, you may have a high BMI but a low body fat percentage. 4
  • It does not take into account the distribution of body fat. People with excess abdominal fat have a higher risk of health problems than those with excess fat in other areas of the body, but BMI does not distinguish between these groups. 5 
  • BMI is calculated the same way for men and women of all ages, even though body fat distribution and metabolism change with age and gender. 6 
  • It was originally developed based on studies of white populations, so it may not be as accurate for people of other races and ethnicities. 7 8

Overall, BMI can be a useful tool for assessing body fatness, but it should not be used in isolation. It’s important to consider other factors such as body composition, body shape, age, gender, race, individual health history, and lifestyle habits when assessing health risks. You can ask your doctor if BMI is an accurate measure for you. 

So what can you do to maintain a healthy weight? 

Seeing progress in BMI can help individuals stay motivated and continue making healthy lifestyle changes. 9 To improve your BMI and maintain a healthy weight, you should:

  • Follow a balanced diet
  • Do at least 150 minutes of moderate physical activity per week
  • Get 7 to 9 hours of sleep each night
  • Manage the stress in your life.

There are lots of things you can do to maintain a healthy weight, so why not introduce some healthy habits today? 

Take care of yourself, 

Dr. Nisha

  1. CDC (2022). Growth Chart Training. Accessed on 30 June 2023.

  2. NIH (2022). Body Mass Index (BMI): A Screening Tool Analysis. Accessed on 30 June 2023.

  3. CDC (2022). Adult Obesity Facts. Accessed on 30 June 2023.

  4. NIH (2011). Body mass index and percentage of body fat as indicators for obesity in an adolescent athletic population. Accessed on 30 June 2023.

  5. Plos Medicine (2012). Long-Term Risk of Incident Type 2 Diabetes and Measures of Overall and Regional Obesity: The EPIC-InterAct Case-Cohort Study. Accessed on 30 June 2023.

  6. NIH (2008). BMI-related errors in the measurement of obesity. Accessed on 30 June 2023.

  7. NIH (2004). Appropriate body-mass index for Asian populations and its implications for policy and intervention strategies. Accessed on 30 June 2023.

  8. The Lancet (2021). Ethnicity-specific BMI cutoffs for obesity based on type 2 diabetes risk in England: a population-based cohort study. Accessed on 30 June 2023.

  9. NIH (2014). Behavioural weight management programmes for adults assessed by trials conducted in everyday contexts: systematic review and meta-analysis. Accessed on 30 June 2023.



Ada is a global health company founded by doctors, scientists, and industry pioneers to create new possibilities for personal health.

Medical reviewer:


Ada is a global health company founded by doctors, scientists, and industry pioneers to create new possibilities for personal health.