Body mass index is not yet an indicator of health
People whose weight does not exceed the norm, but who lack muscle mass, are just as unhealthy as those who are diagnosed with obesity, doctors say. As a result of a study conducted by the American network Mayo Clinic, which has hospitals in three states, it was found that 50% of people with a normal weight-to-height ratio are at risk of obesity due to an incorrect ratio of fat and muscle mass. Previously, experts believed that about two–thirds of the population belong to the risk group, but the identification of a new disease – the so-called obesity at normal weight - suggests that in fact 8 out of 10 people face a serious risk of developing diabetes or heart defects.
The results of a study presented at a scientific conference in the United States on Tuesday cast doubt on the adequacy of such an indicator as body mass index (BMI) as an indicator of human health. BMI is calculated by dividing the weight in kilograms by the square of height expressed in meters. It is considered the norm if this indicator ranges from 18.5 to 25.
However, now doctors claim that 50% of people with a normal BMI have a percentage of body fat too high and this puts their health at risk. In a healthy woman, the proportion of fat in the total weight of her body should be no more than 30%, in men this indicator should be no more than 20%.
Fat mass can be measured using conventional scales or a caliper – a device that measures the thickness of the skin-fat folds in the waist area. According to scientists, taking into account the indicators of body fat mass to detect obesity at normal weight is a more accurate way to determine the degree of health risk than BMI.
"In fact, obesity is an excess of body fat," says Dr. Francisco Lopez–Jimenez, a cardiologist at Mayo Clinic. "Our study shows that even people with normal weight can have excess fat mass. Their health is threatened by metabolic disorders that lead to diabetes or heart defects."
The latter conclusion is consistent with the data of previous studies, which showed that the fat surrounding the abdominal organs (its overabundance is evidenced by the so-called beer belly) is the main risk factor for heart disease. Doctors should measure patients' abdominal volumes or check their body fat mass instead of relying only on BMI, Lopez-Jimenez is sure.
The Mayo Clinic experiment involved 2,127 men and women with a normal body mass index. Their body proportions were measured and blood was taken for analysis. Half of them had elevated levels of cholesterol and leptin in their blood, a hormone that is synthesized by adipose tissue cells and regulates appetite. Such changes in the composition of the blood indicate that a person belongs to a high-risk group.
From the point of view of Dr. Ian Campbell, medical director of the charity Weight Concern, research data show that for people who want to lose weight, physical activity is just as important as diet, because exercise promotes fat burning. According to him, measuring the waist volume can serve as a better indicator of fat mass than the size of trousers. However, in order to obtain more accurate results, in addition to calculating BMI, doctors should conduct special tests for body fat content.
The Daily Telegraph
Translation: ГАЗЕТА.GZT.RU
Portal "Eternal youth" www.vechnayamolodost.ru
04.04.2008