Energy and Micronutrient Intakes Before and After Bariatric Surgery: Nutritional Challenges During the First Postoperative Year

Background/Objectives: Metabolic/bariatric surgery (MBS) markedly reduces food intake, but longitudinal data on food-derived micronutrient intake during the first postoperative year are limited. This study aimed to characterize changes in dietary energy and micronutrient intake before and after sleeve gastrectomy (SG) and Roux-en-Y gastric bypass (RYGB). Methods: Seventy-three patients undergoing MBS (47 SG, 26 RYGB) were included. Dietary intake was assessed using a 24-h dietary recall before surgery and at 1, 6, and 12 months postoperatively. Energy and 12 micronutrients were analyzed using generalized estimating equations adjusted for sex, age, and baseline BMI, with Benjamini–Hochberg correction for multiple testing. Results: Intakes of energy and all micronutrients changed significantly over time (all adjusted p < 0.001) and remained below preoperative values throughout follow-up. For most nutrients, intake was lowest at 1 month and increased only partially by 12 months. No significant main effects of surgical procedure were observed, whereas measurement-by-procedure interactions were significant for energy and zinc. At 12 months, food-derived intake reached only 41–64% of the reference values for calcium, magnesium, iron, and folate. Conclusions: Food-derived energy and micronutrient intakes remained substantially reduced throughout the first postoperative year, supporting continued dietary monitoring alongside guideline-based supplementation and biochemical surveillance after bariatric surgery.