According to an article published in the journal Obesity Reviews, standard methods for measuring obesity may be underestimating the burden of overweight across the globe, possibly missing hundreds of millions.

Associate professors Daniel Hruschka of Arizona State University’s School of Human Evolution and Social Change, and Craig Hadley, of Emory University’s Department of Anthropology, are developing more accurate tools to assess how people’s bodies are built around the world.

In the article “How much do universal anthropometric standards bias the global monitoring of obesity and undernutrition?” the researchers propose that instead of simply using the body mass index (BMI), which is a simple ratio of weight to height, the community should lean toward the idea of “basal slenderness.”

This refers to the expected BMI in a population before it begins to add excess fat from living in an urbanized environment with easy access to high-calorie foods and technology changes that reduce the need to exercise.

The researchers’ hypothesis is that adjusting BMI for a population’s basal slenderness would give each population a cutoff reflecting the amount of a person’s BMI that is due to body fat versus other body tissues.

The authors believe that the benefits of using basal measurements are numerous, such as:

• Health researchers could improve their ability to estimate the number of people who are overweight and underweight, thus enabling more targeted efforts in regions that need it the most;
• Physicians could evaluate their patients’ current and future health needs more accurately;
• Subsequent studies could lead to more effective solutions for obesity prevention and under-nutrition.

BMI is a standard tool for evaluating body fat and for identifying people who are at greater risks of fat-related diseases, such as diabetes or cardiovascular disease. But BMI has been criticized for relying only on height and weight, leading to mistakes when people are naturally stocky and muscular.

On the other hand, naturally slender people might be able to pack on a great amount of body fat before standard BMI measurements categorizes them as overweight or obese.

According to a press release, some countries like Japan or China have already proposed modified measurements for evaluating the risk of obesity and developing obesity-related diseases due to the Asian region’s naturally more slender body type.

There is still no clear basis to adjust BMI conclusively, but the authors presented evidence from a series of studies showing that these variations in human forms are widespread and can have dramatic differences.

The authors claim that by ignoring these differences, researchers might be underestimating adult obesity levels by more than 400 to 500 million people. Given that these differences appear to settle early in childhood years, high-risk areas for child under-nutrition might also be overlooked.