Body mass index (BMI) is a number calculated from a person’s height and weight used to determine health. I have long been arguing against using BMI as a measure of health purely because it is inaccurate. The ratio of height to weight does not take into account whether the weight is due to fat or muscle. Much more important is the distribution of fat in the body which can be measured by the Body Fat Pinch Test, or even the Waist-Height Ratio.
Despite the medical establishment acknowledging that BMI has shortcomings, it is still revered. In the NHS, possibly due to staff following policies laid out to them, a BMI number in the acceptable range can mean a tall overweight patient will not be dealt a talk about their weight. If only they could just look up from the tables and charts sometimes and just look at the person in front of them.
More and more studies are showing the significant dangers of abdominal fat or belly fat or muffin tops or beer bellies. A meta-analysis of five studies showed that belly fat is associated with a 70% increase in risk of death (for coronary artery disease). Belly fat is worse than thigh fat for instance, because it tends to be a sign of visceral fat, the fat that gathers around the organs in the abdomen. This fat seems to promote insulin resistance and unhealthy cholesterol numbers.
This spotlight on abdominal fat could also explain the obesity paradox, whereby overweight and obese patients with cardiovascular disease and/or heart failure appear to fare better than leaner patients.
What baffles me is why the medical world is so unwilling to give up BMI despite the plain evidence that:
“BMI, although widely used, ‘is not a good measure of body fatness and gives no insight into the distribution of fat,’ according to Thais Coutinho, MD, also of the Mayo Clinic, who is the study’s lead author.”
A healthy weight is obviously of the utmost importance, and advice should be given on lifestyle changes to help with that, but it’s equally as important to educate people that your body shape is just as significant as your weight.
Photo credit: Adrian Clark via flickr
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