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Study finds growing “weight extremes” in the developing world

Toronto, January 15, 2013

Obese and overweight people are gaining weight rapidly in low- and middle-income countries while those who are severely undernourished are not experiencing similar weight gains, according to a University of Toronto and Harvard School of Public Health study.

This growing divide may force governments in the developing world to care for people who fall dramatically short on their calorie intake while simultaneously treating health problems associated with obesity, including diabetes and heart disease.

“One might think that as a country grows economically, the majority of the underweight population would move into the average BMI range, but our study shows the opposite: people of average weight are disappearing,” said Fahad Razak, the study’s lead author and a U of T clinical fellow working at St. Michael’s Hospital’s internal medicine unit.

“This growing trend of body weight extremes is going to pose a major challenge for health care and policy leaders,” said Razak. “They will need to balance their priorities between addressing health issues afflicting the underweight who happen to be poor, and health issues afflicting the obese and overweight – the upper middle-class and rich.”

The study uses information collected in Demographic and Health Surveys, an American-led project that tracks health and population trends in developing countries. Researchers analyzed the Body Mass Index of 730,000 women living in 37 countries between 1991 and 2008 and found that as the average BMI in a population increases, the numbers of overweight and obese women are increasing at a much faster rate than the decline in the number of underweight women.

BMI is an indicator of body fat calculated by dividing a person’s weight in kilograms by their height in meters squared. Obesity is defined as having a BMI of more than 30.0 kg/m2. Compared to people with a healthy weight (a BMI between 18.5 and 24.9 kg/m2), obese individuals and overweight individuals (who have a BMI between 25.0 and 29.9 kg/m2) have an increased risk of diabetes, heart disease and stroke, and tend to die younger. At the same time, people who are underweight (BMI less than18.5) also have an increased risk of death, perhaps from complications related to being malnourished.

The researchers’ future work will test whether these patterns are also observed in more developed countries.

The study, “Change in the Body Mass Index Distribution for Women: Analysis of Surveys from 37 Low- and Middle-Income Countries,” is published in the Jan. 15, 2013, issue of PLOS Medicine.

About St. Michael’s Hospital

St. Michael’s Hospital provides compassionate care to all who enter its doors. The hospital also provides outstanding medical education to future health care professionals in more than 23 academic disciplines. Critical care and trauma, heart disease, neurosurgery, diabetes, cancer care, and care of the homeless are among the Hospital’s recognized areas of expertise. Through the Keenan Research Centre and the Li Ka Shing International Healthcare Education Centre, which make up the Li Ka Shing Knowledge Institute, research and education at St. Michael’s Hospital are recognized and make an impact around the world. Founded in 1892, the hospital is fully affiliated with the University of Toronto.