Around the globe, obesity has become a problem for many poorer women in most countries with upper-middle income national economies and even some with lower-middle income economies, an important new international study concludes.
Increasing obesity threatens to undermine the health of women in nations previously not known for a growing percentage of overweight citizens, the researchers say. As the amount of available food grows in most countries, the condition is becoming a greater issue for poorer women than for richer ones.
In the past, health experts and others believed that having a large percentage of the population being overweight was a health issue confined chiefly to wealthier countries such as the United States, England, Germany, Italy and Japan. Obesity makes heart disease, stroke, diabetes, bone and joint problems, some cancers and some other illnesses more likely, doctors say.
Scientists at the University of North Carolina at Chapel Hill and the University of Sao Paulo in Brazil worked together to analyze information from almost 149,000 women between ages 20 and 49 in 37 countries throughout the world. They standardized the data and compared the weight of women from different social classes with how wealthy or poor their countries were.
The findings were released June 2 at a news briefing in Williamsburg, Va., at a Time magazine and ABC News-sponsored conference on obesity. A report on the research will appear in the latest issue of the International Journal of Obesity, which also will be posted electronically June 2.
"In the 20th century, scholars discovered that the poor in high-income countries had more obesity and non-communicable diseases than people who were better off financially," said Dr. Barry M. Popkin, professor of nutrition at the UNC schools of public health and medicine. "But the opposite was true in poorer countries where people could not afford enough food to get fat. As a group, only richer people there suffered the consequences of being too heavy.
"Now, our new work documents a major shift in the burden of disease," Popkin said. "Worldwide, the burden of obesity increasingly rests on the poor and less educated even in many developing nations we never thought of as having an obesity problem."
Others involved in the research were Drs. Carlos Monteiro and Wolney L. Conde, professor and assistant professor of nutrition and epidemiology, respectively, at the University of Sao Paulo, and Bing Lu, a Ph.D. student at UNC.
"Obesity starts to fuel health inequities in the developing world when the gross national product of a country reaches a value of about $2,500 per capita," Monteiro said. "In the absence of concerted national public actions to prevent obesity, economic growth will greatly expand the list of developing countries where this occurs."
Among other findings were that:
Belonging to the lower socioeconomic group in low-income countries -- those with per capita gross national products of below $745 yearly -- conferred strong protection against obesity.
In lower-middle and middle-income economies, belonging to that same lower economic group became a systematic risk factor for obesity at or above $2,995 per capita income.
One possible reason for the inverse association between women’s obesity and their family income in some lower-middle income countries is that after a certain level of economic growth, high-energy expenditures and lack of food are no longer as common in those countries. Another is that poorer people have less education and knowledge about health and more difficulty obtaining more expensive, low-energy dense foods such as fruits, vegetables and whole grain cereals. They also have less time and inclination to exercise.
Support for the global obesity study came from the National Institutes of Health and the Fogerty International Center.
Two limitations of the study were that it only surveyed women of reproductive ages and could only use educational level as a proxy for assessing subjects’ socioeconomic status.