Inflammatory dietary pattern tied to metabolic unhealth in overweight Iranian adults
A higher dietary inflammatory index was associated with a greater likelihood of metabolic unhealth in Iranian adults with overweight or obesity, even though the overall cohort did not show the same pattern. In practical terms, the signal emerged only after body size was taken into account, a reminder that diet-induced inflammation may be most biologically visible in people already carrying excess adiposity.
The study examined 527 men and women living in Isfahan, with a mean age of 42.66 years. Of the total sample, 224 participants, or 42.50%, met criteria for metabolic unhealth using the Wildman definition. Dietary intake was measured with a validated 168-item food frequency questionnaire, and investigators assessed anthropometric, blood pressure, and biochemical markers using standard methods. The design does not prove causation, but it does offer a clinically coherent snapshot of how a more pro-inflammatory eating pattern may track with dysglycemia and atherogenic dyslipidemia.
The clearest signal appeared in overweight and obesity
In the fully adjusted model, the overall population did not show a significant association between dietary inflammatory index and metabolic unhealth. Normal-weight participants also did not show a significant relationship. The association changed in the subgroup with overweight or obesity: those in the third tertile of dietary inflammatory index had significantly higher odds of metabolic unhealth than those in the first tertile, with an odds ratio of 2.76 and a 95% confidence interval of 1.16 to 6.57.
A single sentence captures the clinical direction: in heavier adults, a more inflammatory diet aligned with more metabolic risk.
This pattern fits biologically. Diets richer in pro-inflammatory components can promote insulin signaling defects, oxidative stress, and low-grade systemic inflammation, all of which feed into the cluster of metabolic abnormalities that define metabolic unhealth. Excess adipose tissue may amplify those effects by acting as an inflammatory organ, making the interaction between dietary exposure and body weight especially important. In leaner participants, the same dietary pattern may not have crossed a threshold large enough to show measurable differences in this dataset.
Dysglycemia and triglycerides drove the association
The subgroup analysis pointed to two biochemical domains: hyperglycemia and hypertriglyceridemia. Participants in the third dietary inflammatory index tertile had higher odds of hyperglycemia than those in the first tertile, with an odds ratio of 3.41 and a 95% confidence interval of 1.43 to 8.17. The same comparison for hypertriglyceridemia yielded an odds ratio of 2.13 with a 95% confidence interval of 1.06 to 4.28.
Those two findings matter because they sit at the center of cardiometabolic progression. Elevated glucose reflects impaired insulin action or insufficient compensatory secretion, while triglyceride excess often accompanies hepatic overproduction of very-low-density lipoprotein and reduced lipid clearance. The clinical picture can advance quietly: fasting glucose rises, triglycerides drift upward, and the patient still appears stable at the bedside. By the time the syndrome is obvious, the metabolic injury is often well established.
The study did not report a significant association between dietary inflammatory index and brain-derived neurotrophic factor or adropin. Both markers are of interest because of their proposed roles in energy balance, glucose regulation, and cardiometabolic signaling, but no measurable relationship emerged in this cohort. The absence of association is still informative. It suggests that any effect of dietary inflammatory load on metabolic health in this population was not mirrored by detectable shifts in these two circulating biomarkers, at least under the conditions and assays used here.
Why the biomarker findings stayed flat
BDNF and adropin have attracted attention as candidate mediators between nutrition and metabolic regulation, yet serum concentrations can be influenced by many competing forces, including adiposity, insulin resistance, physical activity, and assay variability. A null result here does not eliminate their biological relevance. It does, however, indicate that the study did not capture a clear intermediary pathway linking dietary inflammation to these circulating markers.
The more immediate translational message sits elsewhere. Dietary inflammation appears to have been more closely tied to observable metabolic abnormalities than to these exploratory biomarkers. In a clinical setting, that means the dietary pattern itself may deserve more attention than an attempt to use BDNF or adropin as routine readouts of risk. The data support that hierarchy.
What the cohort can and cannot tell clinicians
This was an observational study, so the results describe association rather than causation. Dietary intake was estimated using a food frequency questionnaire, which is standard in nutrition epidemiology but still depends on recall and self-report. Even with multivariable adjustment, residual confounding remains possible, especially in a cross-sectional design where diet, body composition, and metabolic status are all measured at the same time.
Still, the sample was not trivial. With 527 adults and a well-defined classification of metabolic health status, the analysis had enough structure to detect subgroup-specific relationships. The fact that the association emerged in overweight and obese participants but not in the full cohort or in normal-weight individuals suggests effect modification by adiposity rather than a universal dietary effect. In clinical terms, excess weight may determine who is most vulnerable to a pro-inflammatory eating pattern.
For clinicians and nutrition researchers, the most actionable inference is narrow but important: among adults carrying excess body weight, a diet with a higher inflammatory burden was linked to worse metabolic health, especially glucose and triglyceride abnormalities. The biomarker story remained negative, and the study did not establish a mechanistic bridge through BDNF or adropin. Future work will need longitudinal follow-up and intervention data to determine whether lowering dietary inflammatory load can reverse these metabolic shifts or whether the association simply marks an already entrenched risk phenotype.