Obesity and iron deficiency: a hidden link?

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Male and female participants aged 18 to 50 years. * Premenopausal women (defined as no absence of menstruation in the past 12 months). * Body Mass Index (BMI) between 35 and 45 kg/m² at recruitment. * Scheduled to undergo bariatric surgery via sleeve gastrectomy or laparoscopic adjustable gastric banding (LAGB), with indications aligned with international guidelines. Bariatric surgery eligibility includes: 1. BMI between 35 and 45 kg/m² with the presence of obesity-related comorbidities (medical, physical, or psychosocial conditions), and a history of unsuccessful attempts at sustained weight loss through non-surgical means. 2. Adequately informed, understanding and accepting the potential risks and benefits of the procedure, and expressing commitment to adhere to long-term dietary and physical activity recommendations post-surgery. * Willing to maintain consistent dietary iron intake and refrain from taking any iron supplements other than those prescribed by the attending surgeon throughout the study duration. * Not pregnant during the study period or in the six months prior to enrollment, and not planning to become pregnant for at least 3 months after the final study visit (at 6 months). * Not breastfeeding in the six weeks prior to enrollment, nor planning to breastfeed during the study. * No significant weight loss (≥10% of body weight) in the six months prior to the pre-surgical evaluation. * Signed informed consent. * No night shift work during the two weeks prior to the baseline visit or at any point during the study (night shift defined as work performed between 12:00 AM and 6:00 AM). * Not engaging in strenuous physical activity ≥10 hours per week. Exclusion Criteria: * Participants who have undergone any bariatric procedure other than LAGB or sleeve gastrectomy. * Severe anemia (defined as hemoglobin \<100 g/L). * History of previous surgical obesity treatments. * Presence of significant medical conditions that may affect iron status or inflammatory markers independently of obesity, including but not limited to: cancer, HIV/AIDS, inflammatory bowel disease, gastrointestinal bleeding, rheumatoid arthritis, and chronic kidney disease (per investigator's judgment). * Diagnosed abnormalities in iron metabolism based on routine pre-surgical blood samples and unrelated to obesity (e.g., thalassemia). * History of frequent blood transfusions. * Chronic liver disease (e.g., alcoholic liver disease, hepatitis C-related liver disease). * Use of medications that could interfere with study measurements (per investigator's judgment). * Women consuming ≥14 alcoholic beverages per typical week or men consuming \>21 alcoholic beverages per typical week.