Endocrine and Metabolic Characteristics and Prognosis of Long COVID Following SARS-CoV-2 Infection During the Omicron Period

Background: The clinical features and recovery of patients with obesity and Long COVID remain incompletely understood. Methods: We retrospectively analyzed 903 patients attending a COVID-19 aftercare clinic during the Omicron period. Biomarkers were compared across body mass index (BMI) categories. Recovery was defined as physician-determined conclusion of outpatient follow-up following sufficient symptom improvement, not necessarily complete resolution. Recovery analyses were exploratory; 572 patients comprised a sensitivity cohort clinically compatible with the World Health Organization (WHO) post-COVID-19 condition definition. Results: Serum ferritin levels were higher in overweight and obese men than in normal-weight men. Cortisol/adrenocorticotropic hormone (ACTH) ratios in women and free thyroxine (FT4) levels in men differed across BMI categories. Recovery analysis from symptom onset included 565 participants and 186 events. Men with obesity had a lower recovery hazard than normal-weight men, with consistent direction across sensitivity analyses (age-adjusted pooled model, n = 565; hazard ratio: 0.390; 95% CI: 0.170–0.894), based on six recovery events among men with obesity. The main sex-by-obesity interaction was nonsignificant; additional interaction results varied by model. The WHO-compatible recovery analysis was limited by sparse events. Conclusions: Obesity was associated with a longer time to clinically defined recovery among men, alongside BMI-related endocrine–metabolic differences. These exploratory findings warrant confirmation; sparse events and residual confounding preclude causal or definitive sex-specific conclusions.