Iron Metabolism in Obesity

This is a prospective observational cohort study designed to evaluate changes in clinical, biochemical, and dietary variables related to iron status in adult individuals undergoing restrictive bariatric surgery (laparoscopic sleeve gastrectomy or adjustable gastric banding) in the urban area of Monterrey, Mexico. The main objective is to assess whether iron status prior to surgery influences weight loss success, inflammatory response, and overall health-related quality of life in the six months following surgery. A total of 50 participants (25 with iron deficiency and 25 without, defined according to WHO standards) will be enrolled. Participants will be classified into groups based on baseline iron status measured using routine preoperative laboratory data. Eligibility criteria include age between 18 and 50 years, premenopausal women, BMI between 35 and 45 kg/m², and eligibility for restrictive bariatric surgery according to international guidelines. Exclusion criteria include prior bariatric surgery, severe anemia (Hb \< 100 g/L), medical conditions that may affect inflammation or iron metabolism, chronic liver disease, recent pregnancy or lactation, recent significant weight loss (\>10% in the last 6 months), shift work, and high levels of physical activity (\>10 hours/week). All participants will be followed for 6 months after surgery. Outcome assessments include anthropometric measurements, laboratory parameters (hemoglobin, ferritin, CRP, among others), dietary intake, and patient-reported outcomes. Dietary intake will be assessed using MyFitnessPal, a mobile app for dietary tracking, with standardized food entries labeled "IRONXL" based on the Mexican food composition database. Participants will be trained to enter food items accurately and consistently. Data from MyFitnessPal will be exported to obtain nutrient intake data. Quality of life and general health status will be measured using the PROMIS Global Health questionnaire, a validated 10-item tool. A structured case report form will collect demographic, medical history, and lifestyle data. Blood samples will be collected and stored for potential future research purposes, pending optional consent by participants. The study will be conducted at the Zambrano Hellion Medical Center, TecSalud. The research team includes qualified surgeons and investigators trained in Good Clinical Practice (GCP). Data quality assurance procedures will include double-entry verification of questionnaire data, standardized anthropometric assessments, and laboratory analyses conducted in accredited clinical laboratories. A Manual of Procedures (MOP) guides all data collection processes. Missing data will be managed through multiple imputation when appropriate, and all analyses will be conducted according to a pre-specified Statistical Analysis Plan (SAP). The primary outcome is change in weight (kg and % of initial body weight) over 6 months. Secondary outcomes include change in hemoglobin, ferritin, CRP, dietary iron intake, and PROMIS scores. The sampling method is non-probabilistic and based on convenience sampling of patients scheduled for surgery who meet the eligibility criteria and agree to participate voluntarily. All participants will provide written informed consent before any study procedures. Optional consent will be obtained for the long-term storage and future analysis of biospecimens (whole blood, serum). These samples may be used in future research related to iron metabolism, inflammation, and nutrition. Participants who decline this optional component will still be eligible to participate in the main study.