Childhood obesity is a problem because it is an important predictor of adult obesity. About one third of obese preschool children become obese adults, and one-half of obese school-age children become obese adults. Most obese adults, however, were not obese children.

Obesity also affects child health. The risk of hyperlipidemia, hypertension, and abnormal glucose tolerance is somewhat higher among obese children. In the United States childhood obesity has important psychosocial consequences: Obese children frequently are targets of systematic discrimination and, by adolescence, many suffer from low self-esteem.

According to WHO, obesity is increasing worldwide at an alarming rate, in both developed and developing countries. WHO issued this conclusion despite the limited availability of nationally representative data and scarce information about trends. The note of alarm led a U.S. team from Emory University (Reynaldo Martorell and Morgen Hughes) and the Centers for Disease Control and Prevention (CDC) (Laura Kettel Khan and Lawrence Grummer-Strawn) to analyze data from national nutrition surveys in the last 15 years to determine obesity levels and trends in developing countries. Most of these surveys focus only on preschool children and women of reproductive age and, therefore, provide limited information about obesity patterns.

In more developed countries, including those in Latin America and the Central Eastern Europe/Commonwealth of Independent States (CEE/CIS) region, obesity levels were higher and more equally distributed in the general population. Obesity ceased to be a distinguishing feature of high socioeconomic status in Brazil, and in Mexico it is emerging as a marker of poverty, as it is in developed countries.

Obesity was more common in urban areas, and was more prevalent in girls and in children of mothers with higher education. At the country level, child obesity was positively related to gross national product and negatively related to stunting.

Other sources suggest that obesity, particularly among adults, is increasing in Micronesia, the Middle East, and Latin America as it is in the United States and Europe. Better data are needed, however, to confirm trends in developing countries.

The results of this study of obesity in women and children in developing countries need to be interpreted with caution because of insufficient data as well as methodological concerns. The reference population used to assess obesity in children is derived from measurements of U.S. children, who may have higher than desired levels of fatness. No consensus on how best to measure obesity in children exists, and the interpretation of weight-for-height indexes in populations with significant levels of stunting has been questioned. There is consensus, however, that a BMI over 30 in adults represents a serious clinical concern. Moreover, risk appears at much lower levels of BMI, and just being overweight (BMI of 25 to 29.9) increases health and mortality risks.

Some countries with high levels of obesity also report significant rates of childhood stunting and nutritional deficiencies. Maintaining a dual nutrition agenda--preventing obesity and related chronic diseases while eliminating nutritional deficiencies--presents a difficult challenge to countries with limited resources. In addition, many countries are unprepared to address the changing epidemiology. Because information about the occurrence of obesity and related chronic diseases in the population is limited, these issues are not considered public health problems. Many countries' nutrition policies continue to focus on undernutrition, limiting experience and expertise with chronic diseases.

Nutrition and healthy lifestyles should be addressed in the school curriculum, and physical activity should be promoted in schools and in the general population. In Singapore, for example, the "Trim and Fit Scheme"--a comprehensive 10-year program that began in 1992--features teacher education and training, assessment of students, a program to reduce sugar in children's beverages, and more physical activity for children during school hours. A recent evaluation of the Singapore program shows a marked improvement in fitness and some evidence of reduction in obesity.

Urban planners can support increased physical activity by building recreational facilities, such as parks and playgrounds. Public education must be as aggressive and effective as commercial advertisements in promoting healthy diets and lifestyles. Food and agricultural policies can stimulate consumption of healthy diets. Nutrition labeling should be required for all industrially prepared foods to help consumers select food. Industry's role in developing healthier food products and in promoting public health and nutrition should be recognized and encouraged. Agricultural research can help shift the macro- or micro-nutrient composition of the food supply. In the U.S. livestock sector, for example, food processing modifications combined with changes in breeding, feeding, and meat-trimming practices have contributed to lower-fat meat.

In much of the developing world, preventing obesity and related chronic diseases should be a priority of governments, as well as of international, bilateral, and national organizations. At the same time, efforts to eliminate nutritional deficiencies must continue.

For further reading see L. Grummer-Strawn, M. Hughes, L. K. Khan, and R. Martorell, "Obesity in Women from Developing Countries," European Journal of Clinical Nutrition 54 (2000): 247-252; same authors, "Overweight and Obesity in Preschool Children from Developing Countries," International Journal of Obesity 24 (2000): 959-967; and World Health Organization, Obesity--Preventing and Managing the Global Epidemic (Geneva, 1998).

Reynaldo Martorell (rmart77@sph.emory.edu) is Robert W. Woodruff Professor of International Nutrition and Chair of the Department of International Health in the Rollins School of Public Health, Emory University, United States.