Fight against obesity goes far beyond individual struggle to change lifestyle, scientists say

Anti-obesity drugs such as Ozempic were the "breakthrough of the year" in 2023, according to the AAAS journal Science. Overweight and obesity rates are rising worldwide, with several Latin American countries in the forefront. Estimates for 2020 pointed to a global obesity rate of 14%, and experts predicted 24% by 2035, including both adults and children.

"Nutritional and pharmacological strategies are important to mitigate the problem, but is this enough? We know socioeconomic and environmental factors influence the occurrence of obesity more than any others, such as genes or blaming people for their own obesity.

"The fact is that obesity goes well beyond the individual struggle against sedentarism and the need for lifestyle changes," said Marcelo Mori, a scientist affiliated with the Obesity and Comorbidities Research Center (OCRC).

Mori is the corresponding author of an article published in the journal Nature Metabolism that stresses the importance of multidisciplinary and global scientific approaches to the problem. Besides Mori and a UNICAMP colleague, the other co-authors are affiliated with the University of São Paulo (USP) and the National Autonomous University of Mexico (UNAM).

The paper argues that the increase in obesity in Latin America is driven mainly by eight factors—the physical environment, food exposure, economic and political interests, social inequality, limited access to scientific knowledge, culture, contextual behavior, and genetics—and that public policies and strategies to combat obesity must acknowledge these drivers if they are to be effective.

"We focused on factors with overlapping effects on weight gain and emphasized the importance of looking at the problem more carefully and broadly, and of intervening on the basis of more contextualized solutions. Are lifestyle changes part of these?

"Indeed they are, but they should above all be associated with changes in the community and the environment rather than being the sole responsibility of the individual. Moreover, regional differences in the socioeconomic and cultural drivers can impact the obesity epidemic, and this means there isn't a single solution to the problem," Mori said.

The authors note that the developed countries had higher obesity rates than developing countries in the past, whereas they are now rising faster in the latter. According to recent data for Latin America, for example, the number of overweight or obese adults as a proportion of the population is 75% in Mexico, 74% in Chile, 68% in Argentina, 57% in Colombia and 55% in Brazil. Among children and adolescents, it is 53% in Chile, 41% in Argentina, 39% in Mexico, 30% in Brazil and 22% in Colombia.

The numbers are rising sharply owing not only to genetic factors or individual choices but also to a combination of structural and contextual factors, the authors argue, calling these factors systemic determinants and proposing a different perspective on the problem of obesity in Latin America.

According to Mori, several studies, especially involving animal models, have shown that both parental malnutrition and overeating, above all by pregnant women, can lead to alterations in offspring that predispose them to metabolic disorders in adulthood.

"Many middle and low-income countries in Latin America and elsewhere have left behind severe undernourishment and are seeing a rapid rise in obesity rates. It's possible that this fast transition from malnutrition to an abundance of ultra-processed and hypercaloric foods is a significant factor in the creation of an epigenetic inheritance that is contributing to the recent rise in obesity rates, especially among children. More research is required to confirm this hypothesis," he said.

Collective action should be the basis for prevention and treatment of obesity, he added. "The article advocates policies to support traditional diet and regulate ultra-processed foods, which are calorie-dense but nutrient-poor. This should be associated with the pursuit of regular physical exercise, healthy habits and nourishing school meals.

"It's also important to motivate pregnant women to follow a healthy diet, breastfeed, and offer their babies healthy food. We argue that the focus should be on women and children, who may be more open to change and at the same time are experiencing the fastest rise in obesity rates in Latin America," he said.

Another determinant of obesity stressed by the researchers is limited access to scientific knowledge.

"Besides lack of scientific knowledge and limited access to open science, we note that investment in research on obesity in Latin America is clearly insufficient, and far too little research is done in proportion to the number of people with obesity. Good work has been published but we need more, and the research that's done needs to be disseminated," Mori said.

Latin American scientific production relating to obesity needs to grow, Mori continued, especially in genetic and social studies.

"Most of these studies are done in countries of the Global North. Until we have much more data on obesity in our own part of the world, we'll continue to see this gap in knowledge about how to mitigate obesity in our region," he said.

"In sum, we import both the problem and the potential solution from the developed countries. We copy their habits and lifestyles and accept the formulas they propose. At the same time, we pay for food products that put us in this position, and for medications that so far have reached only a small proportion of our population. So we pay twice over, and yet we're still losing the fight against the obesity epidemic."