Effect of Weight Loss on Hepcidin Levels and Iron Status in Subjects With Obesity.

The study will consist of two phases: Phase 1, which will be cross-sectional, and Phase 2, which will involve a randomized controlled clinical trial. Phase 1: Cross-Sectional Study A cross-sectional study will be conducted to compare hepcidin levels, iron status and inflammatory markers in people living with and without obesity. Upon obtaining signed consent, participants will undergo a medical history assessment, anthropometric measurements (weight, height, waist circumference), body composition analysis (% body fat, % skeletal muscle mass, % fat-free mass), and blood samples will be collected to determine serum hepcidin levels, iron status, inflammatory markers (C-reactive protein, interleukin-6, lipopolysaccharides), and oxidative stress markers (MDA). Additional blood samples will be taken for biochemical tests (glucose, lipid profile, creatinine, urea, liver function tests), insulin, leptin, adiponectin, and, optionally, DNA isolation for polymorphisms determination and those associated with iron metabolism and obesity. Participants will also complete a food frequency questionnaire (SNUT). Phase 2: Open randomized controlled clinical trial This phase will be conducted to assess the impact of weight loss on hepcidin levels, iron status, and inflammatory markers in individuals living with obesity. Participants recruited for this phase will be selected from those identified in the first phase who exhibit iron deficiency (serum iron \< 50 mcg/dL). Participants will be randomly assigned to one of two dietary intervention groups, both of which will undergo a 60-day follow-up period with a calorie-restricted diet, reducing caloric intake by less than 25% of the resting energy expenditure determined by indirect calorimetry. The intervention groups will be as follows: * Calorie-restricted diet with macronutrient distribution: 1.5 g/kg of ideal body weight in protein (including red meat), 50% carbohydrates, and 25-30% fats. * Calorie-restricted diet with macronutrient distribution: 1.5 g/kg of ideal body weight in protein (excluding red meat), 50% carbohydrates, and 25-30% fats. Additionally, all participants will receive ferrous sulfate 200mg every 48 hours for three months to correct iron-deficiency anemia. During the initial and final visits, participants will undergo a 24-hour dietary recall, complete a physical activity questionnaire, and fill out a quality-of-life questionnaire. Additionally, anthropometric measurements and body composition analysis will be conducted. Blood samples will be collected to determine various biochemical parameters in the blood, including lipid profile (total cholesterol, LDL cholesterol, HDL cholesterol, triglycerides), liver function tests, glucose, insulin, creatinine, urea, oxidative stress markers, inflammatory markers (C-reactive protein and lipopolysaccharides), and iron status markers. Furthermore, stool samples will be collected to analyze the composition of the intestinal microbiota and metabolomics. To assess treatment adherence, participants will be provided with a food logs to record their daily food consumption during the initial visit. The participants will also receive a pantry containing protein-rich foods every week to facilitate the nutritional intervention. Also, 2 phone calls will be made each week to evaluate adherence to treatment. The adherence will be determined with the % of adherence to the dietary treatment as obtained in the analysis of the food logs.