Time trends and projected obesity epidemic in Brazilian

In this study, we used data from 730,309 participants from Vigitel to examine time trends and projected obesity epidemic in Brazil between 2006 and 2030. Between 2006 and 2019, we observed a 30% increase in the prevalence of overweight (from 42.6 in 2006 to 55.4% in 2019), a 72% increase in the prevalence of obesity (from 11.8 to 20.3%) and a 76% increase in the prevalence of obesity classes II and III (from 3.2 to 5.7%). The prevalences of BMI categories by 2030 are estimated to be 68.1% for overweight, 29.6% for obesity and 9.3% for obesity classes II and III.

The obesity epidemic is a global public health concern. In 2016, approximately 1.9 billion adults were living with obesity, and an increasing time trend has been observed in almost every country in the world1. Studies on the projected future trajectories of obesity prevalence are scarce in low- and middle-income countries, despite its potential to inform the need for preventive strategies and preparedness of health systems to cope with obesity consequences. The World Obesity Atlas 2022 have recently estimated that 1 in 5 women and 1 in 7 men will live with obesity by 203012. The global projected prevalence by 2030 is estimated to be 17.5% (approximately, 1 billion people) for obesity and 5.7% (333 million people) for obesity classes II and III. In Brazil, their projected prevalence of obesity is estimated to be 33% for women and 25% for men by 2030, which are similar to our findings (women 30.2%; men 28.8%). Although these findings indicate an increasing obesity epidemic in Brazil, the Brazilian figures are still lower than other countries in Americas and worldwide. By 2030, 1 in 3 men (34.4%) and almost two-fifths of women (39.7%) living in Americas region are predicted to have obesity. The 10 highest projected prevalence of obesity in the Americas region ranged from 47% in US to 32% in Dominican Republic. In the global rank, Brazil is also not listed in the top 20 countries with highest projected prevalence of obesity by 2030 (women: 69% in American Samoa to 50% in Turkey; Men: 67% in Nauru to 39% in Canada). Nonetheless, the increasing prevalence of obesity in Brazil is a concern as it will increase the burden of non-communicable diseases (NCDs) and its associated costs to the Brazilian Unified Health System13.

Our findings indicate socioeconomic disparities in time trends and projected prevalence of obesity epidemic in Brazil. Data from 103 countries has also shown that as countries develop economically, overweight rates rise, affecting poorer individuals more markedly14. Of note, we observed a higher relative increase in the prevalence of overweight between 2006 and 2019 in women, young adults, blacks and other minority ethnicities, and adults with 8–11 years of education. Similar results were observed for absolute increases in the prevalence of obesity. By 2030, 6 out of 10 adults with lower educational attainment (< 7 years of education) are estimated to be living with overweight. Adults with lower educational attainment and blacks and other minority ethnicities may have an even higher prevalence of obesity classes II to III by 2030, compared to its respective counterparts. In Brazil, educational attainment is a good proxy of socioeconomic status. People without access to formal education or those with < 7 years of education (elementary school only) are more likely to have lower socioeconomic status and worse health outcomes15,16. These results corroborate the projected prevalence of obesity in the United States by 2030: 55.6% of participants with household income below $20.000/year will be living with obesity vs 41.7% in participants with higher household income (≥ $50.000/year). Lower educational attainment was also associated with a higher prevalence of obesity classes II to III in US17. These findings suggest that public policies aimed at mitigating obesity inequalities are imperative.

Obesity is a major risk factor for several NCDs, such as cardiovascular diseases, diabetes, and several types of cancer18,19. In 2019, NCDs were responsible for 55% of the 738.371 deaths in Brazil20, of which, 56.1% or 173.207 occurred in adults aged 30–69 years and, therefore, are premature and preventable (in principle). The increasing obesity epidemic has contributed to the increasing burden of cancer in Brazil. Approximately 15,000 cancer cases per year are attributable to high BMI in Brazil, and projections suggest that this number could surpass 29.000 cases by 202518, The worldwide increase in obesity will impact the rise of other NCDs. Projections indicate that type 2 diabetes will affect at least half a billion people by 203021. For each 4 kg/m2 increase in BMI there is a 26% to 56% increase in the risk of ischemic heart disease22. In Brazil, overweight and obesity has caused more than 30,000 deaths per year from cardiovascular diseases, cancers and respiratory diseases23.

Our study has important public health implications. Projected obesity epidemic in Brazil — a middle-income country with limited health care resources — reinforce that primary prevention is pivotal to change obesity trajectories in the country. Our findings also highlight the importance of obesity prevention strategies focusing the whole population, surveillance systems, and prevention research to better evaluate and design public health strategies24. Moreover, our results showed that obesity affect more socioeconomically deprived groups, whose tend to have less access to healthcare and worse health outcomes14. Therefore, public health policies better directed at preventing obesity and reducing social inequalities may reduce the disease burden for future generations, change the predicted trend, and protect vulnerable individuals.

Our predictions assume that no major changes in obesity determinants will take place in the next years. However, since the beginning of the Coronavirus pandemic in 2020, the world has been facing an unprecedent health, economic, and social crises, which disproportionately affect poor individuals and low- to middle-income countries25,26,27. Unemployment and inflation have risen in Brazil, and austerity measures have jeopardized funding for social protection, compromising the food and nutrition security of vulnerable groups28. Thus, we expect that the impoverishment of the population, alongside the limited economic access to healthy food and physical activity might lead to a sharper increase in obesity rates in the near future29.

This study has some limitations. Weight and height were self-reported and therefore misclassification of BMI categories may have ocurred30. In addition, we used hot deck imputation method due to 8.7% missing data of weight or height. The use of landlines in the survey may have included adults with a higher socioeconomic level than the average population of Brazilian capitals31,32. However, BMI results from Vigitel have a high agreement with other nationally representative surveys in Brazil. Similarly, projected obesity epidemic based on adults living in capital cities may not reflect the entire Brazilian adult population, since they are more industrialized and economically developed than the non-capital municipalities. Our model had a moderate to good predictive accuracy.