{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,18]],"date-time":"2026-08-18T05:00:34Z","timestamp":1787029234739,"version":"build-2736575974"},"reference-count":38,"publisher":"MDPI AG","issue":"16","license":[{"start":{"date-parts":[[2026,8,17]],"date-time":"2026-08-17T00:00:00Z","timestamp":1786924800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Nutrients"],"abstract":"<jats:p>Background\/Objectives: Obesity is paradoxically associated with iron deficiency despite adequate dietary intake, driven by chronic inflammation and elevated hepcidin. Different dietary patterns may differentially affect iron metabolism in obese individuals, yet comparative evidence remains limited. Methods: We conducted a systematic literature review following PRISMA 2020 guidelines. Four databases (SciSpace, Google Scholar, PubMed) were searched through 2025 using terms related to obesity, iron deficiency, and three dietary patterns: Mediterranean diet, ketogenic diet, and intermittent fasting. Studies were screened using seven predefined criteria (three inclusion, four exclusion) with thresholds of \u22654.0\/5.0 for abstract screening and \u22654.5\/5.0 for full-text screening. Results: From 396 identified records (SciSpace n = 325, Google Scholar n = 57, PubMed n = 14), 38 studies were included after removing 62 duplicates and screening 334 unique records. Studies without accessible full text were excluded.The Mediterranean diet appears most protective for iron status due to its anti-inflammatory profile (omega-3 fatty acids, polyphenols, vitamin C) and bioavailable iron sources. Ketogenic diets may impair duodenal iron absorption through hepcidin-independent mechanisms and restrict dietary iron diversity. Intermittent fasting shows complex effects, remodeling iron metabolism with increased transferrin and decreased ferritin within physiological ranges. Weight loss per se consistently improves iron status by reducing adipose-driven inflammation and lowering hepcidin. Conclusions: Among the three dietary patterns examined, the Mediterranean diet appears most protective for iron status in obese individuals. The ketogenic diet may pose the highest risk due to restricted dietary iron diversity and potential hepcidin-independent absorption impairment. Direct comparative randomized controlled trials are urgently needed. Clinicians should routinely monitor iron biomarkers, including hepcidin, in obese patients undertaking any dietary intervention. Quantitative biomarker data from the 38 included studies showed serum ferritin reductions of 8\u201328%, hemoglobin levels remaining within clinically stable ranges, and IL-6 decreases of 15\u201342% across dietary patterns.<\/jats:p>","DOI":"10.3390\/nu18162681","type":"journal-article","created":{"date-parts":[[2026,8,17]],"date-time":"2026-08-17T10:04:36Z","timestamp":1786961076000},"page":"2681","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Effects of the Mediterranean Diet, Ketogenic Diet, and Intermittent Fasting on Iron Metabolism and Iron Deficiency Risk in Adults with Obesity: A Systematic Literature Review"],"prefix":"10.3390","volume":"18","author":[{"ORCID":"https:\/\/orcid.org\/0000-0002-7113-2372","authenticated-orcid":false,"given":"Sandro","family":"La Vignera","sequence":"first","affiliation":[{"name":"Department of Clinical and Experimental Medicine, University of Catania (UNICT), Via S. Sofia 78, 95123 Catania, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5217-9343","authenticated-orcid":false,"given":"Rosita","family":"Condorelli","sequence":"additional","affiliation":[{"name":"Department of Clinical and Experimental Medicine, University of Catania (UNICT), Via S. Sofia 78, 95123 Catania, Italy"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,8,17]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1054","DOI":"10.1136\/heartjnl-2020-317802","article-title":"The effect of green Mediterranean diet on cardiometabolic risk; a randomised controlled trial","volume":"107","author":"Tsaban","year":"2021","journal-title":"Heart"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"366","DOI":"10.1016\/j.cmet.2020.06.018","article-title":"Effects of 4- and 6-h Time-Restricted Feeding on Weight and Cardiometabolic Health: A Randomized Controlled Trial in Adults with Obesity","volume":"32","author":"Cienfuegos","year":"2020","journal-title":"Cell Metab."},{"key":"ref_3","unstructured":"Henn, M., Butler, T., and Ordovas, J.M. (2022). The Effect of Diet on Iron Absorption and Status in Obese Adults. Nutrients, 14."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"540","DOI":"10.1016\/j.soard.2013.10.003","article-title":"Nutrient deficiencies in patients with obesity considering bariatric surgery: A cross-sectional study","volume":"10","author":"Lefebvre","year":"2014","journal-title":"Surg. Obes. Relat. Dis."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1412","DOI":"10.1038\/sj.ijo.0803625","article-title":"Inflammation and iron deficiency in the hypoferremia of obesity","volume":"31","author":"Yanoff","year":"2007","journal-title":"Int. J. Obes."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"3587","DOI":"10.3390\/nu6093587","article-title":"Obesity as an emerging risk factor for iron deficiency","volume":"6","author":"Aigner","year":"2014","journal-title":"Nutrients"},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1724","DOI":"10.1038\/oby.2006.198","article-title":"Iron deficiency in obese postmenopausal women","volume":"14","author":"Lecube","year":"2006","journal-title":"Obesity"},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"150","DOI":"10.1111\/j.1467-789X.2011.00938.x","article-title":"The relationship between obesity and hypoferraemia in adults: A systematic review","volume":"13","author":"Cheng","year":"2012","journal-title":"Obes. Rev."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"4425","DOI":"10.1182\/blood-2011-01-258467","article-title":"Hepcidin and iron regulation, 10 years later","volume":"117","author":"Ganz","year":"2011","journal-title":"Blood"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"788","DOI":"10.1053\/j.gastro.2006.07.007","article-title":"Increased adipose tissue expression of hepcidin in severe obesity is independent from diabetes and NASH","volume":"131","author":"Bekri","year":"2006","journal-title":"Gastroenterology"},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"1111","DOI":"10.1038\/ijo.2009.146","article-title":"Overweight children have higher circulating hepcidin concentrations and lower iron status but have dietary iron intakes and bioavailability comparable with normal weight children","volume":"33","author":"Aeberli","year":"2009","journal-title":"Int. J. Obes."},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"1449","DOI":"10.1038\/oby.2009.319","article-title":"Elevated systemic hepcidin and iron depletion in obese premenopausal females","volume":"18","author":"Nemeth","year":"2010","journal-title":"Obesity"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"2090","DOI":"10.1126\/science.1104742","article-title":"Hepcidin regulates cellular iron efflux by binding to ferroportin and inducing its internalization","volume":"306","author":"Nemeth","year":"2004","journal-title":"Science"},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"e34","DOI":"10.1056\/NEJMoa1800389","article-title":"Primary prevention of cardiovascular disease with a Mediterranean diet supplemented with extra-virgin olive oil or nuts","volume":"378","author":"Estruch","year":"2018","journal-title":"N. Engl. J. Med."},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Kosinski, C., and Jornayvaz, F.R. (2017). Effects of Ketogenic Diets on Cardiovascular Risk Factors: Evidence from Animal and Human Studies. Nutrients, 9.","DOI":"10.3390\/nu9050517"},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"2541","DOI":"10.1056\/NEJMra1905136","article-title":"Effects of Intermittent Fasting on Health, Aging, and Disease","volume":"381","author":"Mattson","year":"2019","journal-title":"N. Engl. J. Med."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"975","DOI":"10.3945\/ajcn.110.005439","article-title":"Sharply higher rates of iron deficiency in obese Mexican women and children are predicted by obesity-related inflammation rather than by differences in dietary iron intake","volume":"93","author":"Osendarp","year":"2011","journal-title":"Am. J. Clin. Nutr."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"322","DOI":"10.1111\/j.1467-789X.2009.00638.x","article-title":"Iron in obesity. An ancient micronutrient for a modern disease","volume":"11","author":"Lecube","year":"2010","journal-title":"Obes. Rev."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"1081","DOI":"10.1111\/obr.12323","article-title":"Obesity and iron deficiency: A quantitative meta-analysis","volume":"16","author":"Zhao","year":"2015","journal-title":"Obes. Rev."},{"key":"ref_20","first-page":"1","article-title":"Excessive adiposity is independently associated with elevated serum hepcidin in a sex-specific manner: Findings from the National Adult Nutrition Survey","volume":"125","author":"Heslin","year":"2021","journal-title":"Br. J. Nutr."},{"key":"ref_21","doi-asserted-by":"crossref","unstructured":"Moore, A.H., Donoghue, O.A., Kenny, R.A., and Laird, E. (2021). Risk of Iron Overload in Obesity and Implications in Metabolic Health. Nutrients, 13.","DOI":"10.3390\/nu13051539"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"1092","DOI":"10.2337\/dc13-1602","article-title":"Insulin resistance modulates iron-related proteins in adipose tissue","volume":"37","author":"Moreno","year":"2014","journal-title":"Diabetes Care"},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"215","DOI":"10.1111\/eci.12032","article-title":"Iron homeostasis in the metabolic syndrome","volume":"43","author":"Datz","year":"2013","journal-title":"Eur. J. Clin. Investig."},{"key":"ref_24","first-page":"e13174","article-title":"Effect of weight loss by diet and bariatric surgery on iron status: A systematic review and meta-analysis","volume":"22","author":"Teng","year":"2021","journal-title":"Obes. Rev."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"1030","DOI":"10.3945\/ajcn.115.115592","article-title":"The effects of fat loss after bariatric surgery on inflammation, serum hepcidin, and iron absorption: A prospective 6-mo iron stable isotope study","volume":"104","author":"Osendarp","year":"2016","journal-title":"Am. J. Clin. Nutr."},{"key":"ref_26","doi-asserted-by":"crossref","unstructured":"Brisebois, G., Goldenberg, R., and Bhatt, D.L. (2021). Iron Deficiency in Obesity and after Bariatric Surgery. Biomolecules, 11.","DOI":"10.3390\/biom11050613"},{"key":"ref_27","doi-asserted-by":"crossref","unstructured":"Kaminska, W., Bak, J., Skonieczna-Zydecka, K., Krajewska, K., Jedrzejewski, M., and Zurawska-Plaksej, E. (2025). Estimation of New Regulators of Iron Metabolism in Short-Term Follow-Up After Bariatric Surgery. Int. J. Mol. Sci., 26.","DOI":"10.3390\/ijms262110543"},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"n71","DOI":"10.1136\/bmj.n71","article-title":"The PRISMA 2020 statement: An updated guideline for reporting systematic reviews","volume":"372","author":"Page","year":"2021","journal-title":"BMJ"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"29","DOI":"10.1186\/s13073-022-01015-z","article-title":"The effects of the Green-Mediterranean diet on cardiometabolic health are linked to gut microbiome modifications: A randomized controlled trial","volume":"14","author":"Rinott","year":"2022","journal-title":"Genome Med."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.jnutbio.2015.08.024","article-title":"Nutritional therapy for nonalcoholic fatty liver disease","volume":"29","author":"Dongiovanni","year":"2016","journal-title":"J. Nutr. Biochem."},{"key":"ref_31","doi-asserted-by":"crossref","unstructured":"Aguree, S., and Reddy, M.B. (2021). Inflammatory Markers and Hepcidin are Elevated but Serum Iron is Lower in Obese Women of Reproductive Age. Nutrients, 13.","DOI":"10.3390\/nu13010217"},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"e70110","DOI":"10.1002\/edm2.70110","article-title":"Revisiting the Obesity-Anaemia Paradox: Inflammation and Iron Homeostasis in the BMI-Haemoglobin Relationship","volume":"8","author":"Ali","year":"2025","journal-title":"Endocrinol. Diabetes Metab."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"263","DOI":"10.1024\/0300-9831\/a000033","article-title":"Does obesity increase risk for iron deficiency? A review of the literature and the potential mechanisms","volume":"80","author":"Aeberli","year":"2010","journal-title":"Int. J. Vitam. Nutr. Res."},{"key":"ref_34","first-page":"1","article-title":"The Impact of Obesity and Insulin Resistance on Iron and Red Blood Cell Parameters: A Single Center, Cross-Sectional Study","volume":"16","author":"Erem","year":"2012","journal-title":"Turk. J. Endocrinol. Metab."},{"key":"ref_35","first-page":"1025","article-title":"The Role of Iron Overload on Systematic Iron Homeostasis, Proinflammatory Biomarkers and Obesity Etiopathogenesis","volume":"12","year":"2016","journal-title":"Jordan J. Agric. Sci."},{"key":"ref_36","first-page":"656","article-title":"Bariatric Surgery Can Correct Iron Depletion in Morbidly Obese Women: A Link with Chronic Inflammation","volume":"18","author":"Aarts","year":"2008","journal-title":"Obes. Surg."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"1105","DOI":"10.1042\/BST20160474","article-title":"Omega-3 fatty acids and inflammatory processes: From molecules to man","volume":"45","author":"Calder","year":"2017","journal-title":"Biochem. Soc. Trans."},{"key":"ref_38","doi-asserted-by":"crossref","unstructured":"Figueiredo, P.S., Inada, A.C., Marcelino, G., Cardozo, C.M.L., Freitas, K.C., Guimaraes, R.C.A., Pott, A., Bogo, D., Vilela, M.L.B., and Hiane, P.A. (2017). Fatty Acids Consumption: The Role Metabolic Aspects Involved in Obesity and Its Associated Comorbidities. Nutrients, 9.","DOI":"10.3390\/nu9101158"}],"container-title":["Nutrients"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2072-6643\/18\/16\/2681\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,8,17]],"date-time":"2026-08-17T10:17:06Z","timestamp":1786961826000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2072-6643\/18\/16\/2681"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,8,17]]},"references-count":38,"journal-issue":{"issue":"16","published-online":{"date-parts":[[2026,8]]}},"alternative-id":["nu18162681"],"URL":"https:\/\/doi.org\/10.3390\/nu18162681","relation":{},"ISSN":["2072-6643"],"issn-type":[{"value":"2072-6643","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,8,17]]}}}