An international multi-center study has revealed how diet plays a greater role in the prevalence of obesity globally than was previously understood, according to findings published in the Proceedings of the National Academy of Sciences.
“The differences in daily energy expenditure between folks in the industrialized world and subsistence populations are not as great as we might have expected, whereas the shifts in diets that we’re seeing with populations that are moving from a subsistence life way into a market-oriented way of life are much, much greater,” said William Leonard, PhD, professor of Preventive Medicine in the Division of Behavioral Medicine and the Watkins Family Professor of Global Health in the Weinberg College of Art and Sciences, who was a co-author of the study.
Global economic development has been associated with an increase in obesity globally, which accounts for more than 4 million deaths worldwide each year, according to recent reports.
Increased caloric intake, as well as reduced energy expenditure, have both been attributed to a sharp increase in obesity and obesity-related health problems in industrialized countries. Which side of this energy balance, however — increased caloric intake or reduced energy expenditure — plays a larger role in the obesity prevalence around the world has remained poorly understood.
In the current study, an international team of scientists studied energy expenditure and two measures of obesity — body fat percentages and body mass index (BMI) — in more than 4,000 adults across six continents representing a range of geographic locations, lifestyles and economic status.
Data were compiled from the International Atomic Energy Agency Doubly Labelled Water Database. The doubly labeled water method uses the rate of isotope depletion from the body water pool to calculate the rate of carbon dioxide production and, therefore, energy expenditure over a 7- to 14-day period.
Comprehensive data analyses revealed that economic development was positively associated with greater body mass, BMI and body fat, but also with greater total, basal and activity energy expenditure.
On the other hand, estimated energy intake was greater in economically developed populations and the percentage of ultra-processed food in a population’s diet was also associated with body fat percentage.
The findings suggest that dietary intake plays a greater role than reduced energy expenditure in the increased prevalence of obesity associated with economic development.
“Shifting from producing your own food and eating whole foods that you are growing or capturing on your own to a diet that includes a lot of refined food products, sugars and fats seems to be really shifting the energy balance in a substantial way and leading to these changes that we’re seeing,” said Leonard, who is also co-director of the Center Global Health Education in the Robert J. Havey, MD Institute for Global Health.
According to Leonard, the findings emphasize the importance of being more attentive to how modest changes in dietary intake can alter body composition and contribute to chronic health problems associated with obesity.
“We need a continued emphasis on dietary patterns that emphasize whole foods, fruits and vegetables as an important part of the diet and keeping a lid on consumption of things like highly processed foods and large amounts of sugar,” Leonard said.
This work was supported by the U.S. National Science Foundation grant BCS-1824466, Chinese Academy of Sciences Grant CAS grant 153E11KYSB20190045, Taiyo Nippon Sanso (DLW Database), and Sercon Group (DLW Database).
