BMI Body Mass Index and health risk in children, role in heart disease, is this test reliable?
June 5 2016 by
Ray Sahelian, M.D.


Body Mass Index, invented by Belgian Adolphe Quetelet between 1830 and 1850, is a measure of body fat calculated from height and weight.
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BMI not reliable?

Nutrition experts and doctors have different viewpoints when it comes to the importance of BMI in relation to heart disease and longevity. Body Mass Index (BMI), the standard measure of obesity, may be flawed.  Writing in Lancet medical journal, researchers from the Mayo Clinic College of Medicine, Rochester, Minnesota, found that patients with a low BMI had a higher risk of death from heart disease than those with normal BMI. At the same time overweight patients had better survival rates and fewer heart problems than those with a normal BMI. This apparently unexpected result, drawn from data from 40 studies covering 250,000 people with heart disease, did not suggest that obesity was not a health threat but rather that the 100-year-old BMI test was too blunt an instrument to be trusted with predictions about health and mortality.


A better test?
BMI or Body Mass Index, a ratio of weight to height, has long been considered one of the best measures for assessing overall health risk. However, recent research shows that there is a better measurement: your waist-to-height ratio (WHtR). Studies now indicate that WHtR is a much better measure than BMI for assessing obesity and cardiovascular risk. People with the most weight around their waists are at greatest risk of diseases such as heart disease and diabetes. Therefore, since you can't change your height, you should take special care to keep your weight and in particular, abdominal girth in a healthy range by eating nutritiously and exercising regularly. The WHtR is derived by dividing waist size by height, and takes gender into account. As an example, a male with a 32 inch waist who is 5'10" (70 inches) would divide 32 by 70, to get a WHtR of 45.7 percent.


A better test than BMI?
Maria Grazia Franzosi from the Istituto Mario Negri in Milan, writing in the same issue of the Lancet, noted that a 52-country study comparing four different tests -- BMI, waist-to-hip ratio, waist measure and hip measure -- found that waist-to-hip was the best predictor of heart attack risk.

BMI and breast cancer survival risk
A higher body mass index BMI is associated with lower survival rates in women with breast cancer.


BMI in children and heart disease
As BMI during childhood climbs, so does the risk of coronary heart disease in adulthood.


PLoS One. 2014. Association of body mass index with all-cause and cardiovascular disease mortality in the elderly. To evaluate the associations of body mass index (BMI) with all-cause, cardiovascular disease (CVD), and expanded CVD mortality in the elderly. Observational cohort study. The associations of BMI with all-cause, CVD, expanded CVD mortality in the elderly are represented by U-shaped curves, suggesting unilateral promotions or interventions in weight reduction in the elderly may be inappropriate.


Heart failure
Circ Heart Fail. 2015. Body Mass Index and Heart Failure Among Patients with Type 2 Diabetes. Our study suggests a positive association between BMI and HF risk among men, and a J-shaped association between BMI and HF risk among women with type 2 diabetes.


Gallstone risk
An elevated body mass index is not just associated with symptomatic gallstone disease, it appears to cause the disease.


BMI calculator
A BMI of less than 18.5 is considered underweight, while from 18.5 to 24.9 is normal, 25 to 29.9 is overweight and anything over 30 is categorized as obese. Intended as a broad indicator of general health, BMI has become a standard diagnostic tool of heart disease risk.