Weekly fast-food consumption was the most consistent adverse dietary marker associated with all prevalent cardiometabolic outcomes (excess weight, obesity, hypertension, and diabetes) in the 2023 Spanish Health Survey, while patterns consistent with age confounding and possible reverse-causality bias were identified for other dietary proxies.
Prevalence of excess weight, hypertension, and diabetes in the 2023 Spanish Health Survey sample was high.
Weekly fast-food consumption was consistently associated with excess weight and obesity.
Weekly fast-food consumption was associated with prevalent hypertension and prevalent diabetes.
Excluding participants with severe chronic comorbidities strengthened the association between fast-food consumption and prevalent diabetes.
Processed meat was specifically associated with prevalent excess weight and obesity but not with prevalent cardiometabolic diagnoses such as hypertension or diabetes.
Stratified and sensitivity analyses revealed empirical patterns consistent with age confounding and possible post-diagnosis dietary changes (reverse causality) influencing cross-sectional associations.
The study used dietary proxy mapping rather than direct NOVA classification to characterize ultra-processed food exposure.
This research used data from 21,032 people surveyed in the 2023 Spanish Health Survey to examine whether eating ultra-processed foods — particularly fast food and processed meat — was linked to common health problems like obesity, high blood pressure, and diabetes. The study found that people who ate fast food at least weekly were more likely to have all four of these health conditions compared to those who ate it less often. Processed meat was linked to being overweight or obese, but not specifically to high blood pressure or diabetes diagnoses. The researchers also investigated whether the study's design could distort the results. Because this was a snapshot survey (cross-sectional), people who had already been diagnosed with conditions like diabetes or hypertension may have changed their diets after diagnosis, potentially making their current diets look healthier than before — a problem called reverse causality. The researchers tested this by removing participants with severe chronic illnesses from the analysis and found that the link between fast food and diabetes actually became stronger, suggesting that reverse causality was not fully explaining the fast-food findings. This research suggests that fast food consumption is a meaningful marker of cardiometabolic risk even in national survey data, but it also highlights important limitations of cross-sectional health surveys. Age differences between groups and dietary changes after diagnosis can distort associations, making some harmful foods appear safer or even protective. The authors caution that results from this type of study require careful interpretation and should not be used uncritically in public health policy without accounting for these potential biases.
Cuadrado-Corrales N, Zamorano-León J, Carabantes-Alarcón D, Mérida D, Bodas-Pinedo A, Chico-Rodríguez M, et al.. (2026). Ultra-Processed Food-Rich Dietary Proxies, Dietary-Pattern Context, and Cardiometabolic Outcomes in Spain: Weighted Evidence Consistent with Age Confounding and Possible Reverse-Causality Bias from the 2023 Spanish Health Survey.. Nutrients. https://doi.org/10.3390/nu18162615