TEL-AVIV, Israel — Obesity may be even more prevalent in society than many people think. New research out of Israel reports roughly one-third of “normal weight” individuals are actually “obese with normal weight.” Scientists at Tel-Aviv University say that the widely used BMI (Body Mass Index) measurement isn’t as sensitive as most believe when it comes to defining obesity.
In light of these findings, the research team recommends equipping health clinics with devices capable of measuring body fat percentage, eventually turning body fat measurements into the gold standard of obesity (to assess excess fat) both in Israel and across the world.
Study authors analyzed roughly 3,000 Israeli women and men, ultimately concluding that body fat percentage is a much more reliable indicator of an individual’s overall health and cardiometabolic risk than BMI — which is widely used across healthcare settings today.
This project was the largest of its kind to date to ever be conducted in Israel. It was led by Prof. Yftach Gepner and PhD student Yair Lahav, in collaboration with Aviv Kfir. Researchers worked with data provided by the Yair Lahav Nutrition Center in Tel Aviv.
“Israel is a leader in childhood obesity and more than 60% of the country’s adults are defined as overweight. The prevailing index in this respect is BMI, based on weight and height measures, which is considered a standard indicator of an individual’s general health. However, despite the obvious intuitive connection between excess weight and obesity, the actual measure for obesity is the body’s fat content, with the maximum normal values set at 25% for males and 35% for females,” Prof. Gepner says in a university release.
“Higher fat content is defined as obesity and can cause a range of potentially life-threatening cardio-metabolic diseases: heart disease, diabetes, fatty liver, kidney dysfunction, and more. The disparity between the two indexes has generated a phenomenon called ‘the paradox of obesity with normal weight’ – higher than normal body fat percentage in normal-weight individuals. In this study we examined the prevalence of this phenomenon in Israel’s adult population.”
Researchers analyzed the anthropometric data of these 3,000 participants, which had been gathered over the course of several years. The data included BMI scores, DXA scans (using X-rays to measure body composition, including fat content), and cardiometabolic blood markers.
Roughly one-third of the participants, or 1,000 individuals, were found to be within the normal weight range. However, among that cohort, 38.5 percent of the women and 26.5 percent of the men were identified as being “obese with normal weight,” or having excess fat content despite their normal weight.
After matching up body fat percentage with blood markers for each person, researchers discovered a correlation between “obesity with normal weight” and high levels of sugar, fat, and cholesterol – which are all big risk factors for numerous cardiometabolic diseases. Meanwhile, 30 percent of the men and 10 percent of the women deemed overweight were actually found to have a normal body fat percentage.
“Our findings were somewhat alarming, indicating that obesity with normal weight is much more common in Israel than we had assumed. Moreover, these individuals, being within the norm according to the prevailing BMI index, usually pass ‘under the radar’. Unlike people who are identified as overweight, they receive no treatment or instructions for changing their nutrition or lifestyle – which places them at an even greater risk for cardio-metabolic diseases,” Prof. Gepner explains.
In conclusion, the research team says body fat percentage is a more reliable indicator of an individual’s general health than BMI. Thus, they recommend that body fat percentage be positioned as the new prevailing standard of health. A number of convenient and accessible tools could be utilized to this end. For example, skinfold measurements that estimate body fat based on the thickness of the fat layer under the skin, or a user-friendly device capable of measuring the body’s electrical conductivity.
“Our study found that obesity with normal weight is very common in Israel, much more than we had previously assumed, and that it is significantly correlated with substantial health risks. And yet, people who are ‘obese with normal weight’ are not identified by today’s prevailing index, BMI,” Prof. Gepner concludes.
“We also found that body fat percentage is a much more reliable indicator than BMI with regard to an individual’s general health. Therefore, we recommend equipping all clinics with suitable devices for measuring body fat content, and gradually turning it into the gold standard both in Israel and worldwide, to prevent disease and early mortality.”
The study is published in the journal Frontiers in Nutrition.