How Useful is BMI?

Contributed by Angela Fitch, MD

BMI179620144-300x200Most social science research related to obesity uses body mass index (BMI), calculated using self-reported weight and height. This is despite agreement in the medical community that such measures are seriously flawed because they do not distinguish fat from muscle and bone mass, nor does it take into account age or gender.BMI has been used for many years by doctors, personal trainers, and other health care professionals, when deciding whether patients are overweight but it is only a rough guide to help people judge whether they have a healthy weight.

If you use only the BMI formula, most athletes are considered as fat or fatter than couch potatoes – which is obviously completely wrong. This is because athletes are much more muscular than couch potatoes – muscle weighs more than fat.

We would all love to be told clearly how much we should weigh and how to calculate this ourselves. Unfortunately, your ideal weight is not a black and white formula.

You cannot simply calculate your healthy weight from a general source – it depends on several factors, including your overall general health, height, muscle-fat-ratio, bone density, body type, sex, and age.

Determining one’s BMI may give people a rough idea of how much they should weigh. BMI is useful when studying large populations, but not for individuals. It turns out the circumference around a person’s waist may provide a more accurate reading of his or her abdominal fat and risk for disease than BMI. And wrapping a tape measure around your waist is no more expensive than hopping on a scale and standing in front of a ruler. That’s why the American Society for Nutrition, the American Diabetes Association, and other prominent medical groups have lately promoted waist circumference measurements as a supplement to, or replacement for, BMI.

But few doctors have made the switch because waist measurements require slightly more time and training than it takes to record a BMI reading, and they don’t come with any official cutoffs that can be used to make easy assessments. The BMI is inexpensive and easy, and it has been used for years. In short, BMI is here to stay—despite its flaws.

Our weight loss and nutrition experts are committed to building a better health profile for women based on body fat and the risk of chronic disease and have included waist circumference measurements as a standard protocol in daily clinical practice. We also offer additional tools for success.

As an academic health system, UC Health hopes to someday obtain funding to further study and understand how different body weight and body fat profiles are related to risk for chronic disease in women. Studies similar to the one being conducted by Massey University are looking at whether a body mass index profile really can tell whether someone is healthy. Principal investigator for that study, Associate Professor Rozanne Kruger – from the Institute of Food, Nutrition and Human Health (IFNHH) – says it’s a chance for women to get a benchmark of their current health, and help build more accurate profiles for future health guidance. You can find out more about the study here.

Experts in medical weight loss, nutrition and bariatric surgery work collaboratively in the Metabolic Health and Weight Management Program at UC Health Women’s Center to see to it that patients achieve long-term success in taking control of their health. For more information about the program, please call (513) 475-UC4U or the Weight Loss Center (513) 939-2263.

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