Researchers from the Johns Hopkins Bloomberg School of Public Health, Cienfuegos, Cuba and Loyola University had a unique opportunity to observe the impact of population-wide weight loss due to sustained reductions in caloric intake and an increase in energy output.

This situation occurred during the economic crisis of Cuba in 1989-2000. As a result, obesity declined, as did deaths attributed to diabetes, coronary heart disease and stroke.



"This is the first, and probably the only, natural experiment, born of unfortunate circumstances, where large effects on diabetes, cardiovascular disease and all-cause mortality have been related to sustained population-wide weight loss as a result of increased physical activity and reduced caloric intake," said Manuel Franco, MD, a PhD candidate in the Bloomberg School of Public Health's Department of Epidemiology.

"Population-wide approaches designed to reduce caloric intake and increase physical activity, without affecting nutritional sufficiency, might be best suited for the prevention of cardiovascular disease and diabetes."

The study authors gathered data on energy intake, body weight and physical activity using previously published literature from the Cuban National Institute of Hygiene, Epidemiology and Microbiology, the Food and Agriculture Organization of the United Nations, the Cuban First and Second National Surveys on Risk Factors and Chronic Diseases and the Cuban Ministry of Public Health.

There was a drop in the daily per capita food availability from the late 1980s to 1995, resulting in a daily energy intake decline from 2,899 kcal in 1988 to 1,863 kcal in 1993. In 1987, 30 percent of Havana residents were physically active. From 1991 to 1995, 70 percent of Cubans were physically active as a result of widespread use of bicycles and walking as means of transportation. Obesity prevalence in Cienfuegos, Cuba, decreased from 14.3 percent in 1991 to 7.2 percent in 1995.

During the end of the Cuban economic downturn and the years following it, there were substantial declines in cardiovascular disease, type 2 diabetes and all-cause mortality. The researchers report a plateau in the number of deaths from diabetes during the food shortage of 1988-1996, when physical activity increased and obesity decreased.

"Future steps towards prevention of cardiovascular disease and diabetes should focus on long-term population-wide interventions by encouraging physical activity and the reduction of caloric intake," explained Franco, who is also affiliated with the Johns Hopkins Welch Center for Prevention and Epidemiology.

Johns Hopkins researchers Manuel Franco, Benjamin Caballero, Mariana Lazo and Eliseo Guallar co-authored "Impact of Energy Intake, Physical Activity and Population-wide Weight Loss on Cardiovascular Disease and Diabetes Mortality in Cuba, 1980-2005". Additional co-authors are Pedro Orduñez, Jose A. Tapia Granados, Jose Luis Bernal and Richard S. Cooper.

The study was published September 19, 2007, as an Advance Access study by the American Journal of Epidemiology.

Dr. Manuel Franco was funded by grants from the Fulbright Commission and the Welch Center for Prevention, Epidemiology and Clinical Research.