Rocío Barragán
Assistant Professor in the Department of Preventive Medicine and Public Health at the University of Valencia, and researcher at the CIBER Centre for the Physiopathology of Obesity and Nutrition (CIBEROBN) at the Carlos III Institute
Is the study of good quality?
Yes, this is a methodologically robust, high-quality study based on a very large sample comprising approximately 232 million participants from different countries and age groups. The research analyses temporal trends in age-standardised obesity prevalence in both adult and paediatric populations, allowing for robust international comparisons.
In addition, the study not only evaluates obesity prevalence itself, but also the rate at which this prevalence is changing, providing valuable insight into the epidemiological dynamics of obesity across different regions of the world. The breadth of the dataset and the use of statistical modelling further strengthen the validity of the findings.”
Are there any limitations that should be taken into account?
“In addition to the limitations acknowledged by the authors, one of the study’s main limitations is the use of body mass index (BMI) as the diagnostic criterion for obesity. Although BMI is the most widely used tool and is recommended by the WHO because of its simplicity, reproducibility and standardisation, it has important limitations in terms of clinical validity, as it does not distinguish between fat mass and muscle mass, nor does it take fat distribution into account.
Related to this, there are ethnic differences in the relationship between BMI and cardiometabolic risk. For example, in Asian populations, obesity-related risk may arise at BMI values below 30 kg/m², meaning that the use of a single universal cut-off point could underestimate the true prevalence of obesity in certain population groups.”
What are the implications of the study, and how does it fit with the existing evidence?
“Analysing obesity trends is of enormous importance for public health, given that obesity remains one of the leading global health challenges. The study’s findings reveal considerable heterogeneity between countries, age groups and sexes, reinforcing the need to design preventive strategies tailored to specific populations.
The study is consistent with previous evidence indicating that obesity is the epidemic of the 21st century. However, these data also suggest that sustained public health policies over time can be effective in reducing, and even reversing, obesity trends. Nevertheless, these improvements are mainly observed in wealthier, more economically developed countries. Likewise, within individual countries, despite the overall reductions observed, more disadvantaged groups continue to be disproportionately affected and should therefore be prioritised in prevention and health-promotion policies.”
In Spain, not only has the rise in obesity slowed, but it has even shown a slight reversal, making it one of the few countries where this has occurred. What might explain this?
“Although the prevalence of overweight and obesity in Spain remains high, the study’s findings suggest a slight reversal in obesity trends in recent years, which may be explained by several factors.
On the one hand, Spain has a universal healthcare system and a public health infrastructure that facilitate the implementation of preventive strategies and campaigns promoting healthy lifestyles. On the other hand, certain sociocultural factors — such as partial adherence to the Mediterranean diet, greater consumption of fresh foods, and lifestyle habits characteristic of Mediterranean countries — may also help to curb the rise in obesity.”