I’ve ranted before about the problems using BMI to try and determine if one is overweight or not. The Body Mass Index (BMI) was created to review large (excuse the pun) populations, NOT individuals. As Wikipedia notes on explaining the creation of the BMI:
BMI was explicitly cited by Keys as being appropriate for population studies, and inappropriate for individual diagnosis. Nevertheless, due to its simplicity, it came to be widely used for individual diagnosis, despite its inappropriateness.
The article further clarifies:
BMI has become controversial because many people, including physicians, have come to rely on its apparent numerical authority for medical diagnosis, but that was never the BMI’s purpose…
I explained in an earlier blog that hip to waist measurement is actually a much better predictor of obesity than BMI. Just Google “BMI vs. hip to waist ratio” and you’ll see all the studies. One of the quotes from these studies is:
Cutlip agrees that BMI can be way off, especially when it comes to assessing a particular individual. The commonly used measure can give a skewed result not only for fit body builders who come out with a high number because of the extra weight associated with muscle, but also for the elderly, who tend to have scores that underestimate obesity because they have so much less muscle.
The study succinctly states:
New research shows that there’s a better, more informative way to figure out if you are overweight — the waist-to-hip ratio
Now these studies are from 6 years ago! So why when I go to see my doctor do the nurses still take my height and weight to work out my BMI (and then consequently tell me that I am overweight)! Why aren’t they taking my hip and waist measurements?
I’m not sure. Maybe it is perhaps some conspiracy with insurance companies, pharmaceutical companies and doctors. Obesity is big business = big money. When I applied for life insurance one of the companies wanted to double my premium because my BMI showed I was “overweight”. Hang on, I said, my body fat percentage is at the level of an athlete – who are you calling fat?
Then this last week I see another study has been produced showing that using BMI as a measurement of “fatness” is flawed. “But hang on” I hear you say, “if the BMI is right in about 90% of cases, isn’t it worth hanging on to it?”. Absolutely – if it will pick up 90 out of 100 people correctly (sorry to the remaining 10 who will get ‘misdiagnosed’). So how accurate is BMI? Here is the kicker:
An analysis comparing the BMI to a blood test and body scan found that the BMI was wrong for half of women and 1 in 4 men.
Yep, you read that right – BMI is wrong in 50% of cases for women.