Adetunmise Oluseyi Olajide
Harvard T.H. Chan School of Public Health – ECPE, Principles and Practice of Clinical Research (PPCR) Program, Boston, MA, USA; Department of Maternal and Child Health Nursing, Faculty of Nursing Sciences, Ladoke Akintola University of Technology, Ogbomoso, Oyo State, Nigeria
Alejandra Gallego Rivas
Harvard T.H. Chan School of Public Health – ECPE, Principles and Practice of Clinical Research (PPCR) Program, Boston, MA, USA; Somer Incare Cardiovascular Center, Rionegro, Antioquia, Colombia
Amanda Lucia Armendariz Ortiz
Harvard T.H. Chan School of Public Health – ECPE, Principles and Practice of Clinical Research (PPCR) Program, Boston, MA, USA; Facultad de Medicina, Universidad Francisco Marroquin, Guatemala City, Guatemala
Ana Beatriz Sampaio Pinto de Castro
Harvard T.H. Chan School of Public Health – ECPE, Principles and Practice of Clinical Research (PPCR) Program, Boston, MA, USA; Institution Virtú Ophthalmology, Belo Horizonte, Brazil
Belkis Gabriela Franco Malaver
Harvard T.H. Chan School of Public Health – ECPE, Principles and Practice of Clinical Research (PPCR) Program, Boston, MA, USA
Claudia Reyes Aguirre
Harvard T.H. Chan School of Public Health – ECPE, Principles and Practice of Clinical Research (PPCR) Program, Boston, MA, USA; Hospital del Trabajador ACHS Salud, Santiago, Chile
Cristina Oliveira
Harvard T.H. Chan School of Public Health – ECPE, Principles and Practice of Clinical Research (PPCR) Program, Boston, MA, USA
Eugenia Rojas
Harvard T.H. Chan School of Public Health – ECPE, Principles and Practice of Clinical Research (PPCR) Program, Boston, MA, USA
Fatima Ramos
Harvard T.H. Chan School of Public Health – ECPE, Principles and Practice of Clinical Research (PPCR) Program, Boston, MA, USA; Escuela de Medicina, Universidad Peruana de Ciencias Aplicadas, Lima, Peru
Felipe Marques da Costa
Harvard T.H. Chan School of Public Health – ECPE, Principles and Practice of Clinical Research (PPCR) Program, Boston, MA, USA; Beneficência Portuguesa de São Paulo, São Paulo, Brazil
Gabriella Freaza
Harvard T.H. Chan School of Public Health – ECPE, Principles and Practice of Clinical Research (PPCR) Program, Boston, MA, USA; Bahiana School of Medicine and Public Health, Salvador, Bahia, Brazil
Hawraa Shwaylia
Harvard T.H. Chan School of Public Health – ECPE, Principles and Practice of Clinical Research (PPCR) Program, Boston, MA, USA; National Center for Cancer Care and Research, Hamad Medical Corporation, Doha, Qatar
Iñaki Xavier Bizama Brahm Bizama Brahm
Harvard T.H. Chan School of Public Health – ECPE, Principles and Practice of Clinical Research (PPCR) Program, Boston, MA, USA; Hospital del Trabajador ACHS Salud, Santiago, Chile
Jarline Esther Cruz Santana
Harvard T.H. Chan School of Public Health – ECPE, Principles and Practice of Clinical Research (PPCR) Program, Boston, MA, USA
Joao Victor Starling Magalhaes
Harvard T.H. Chan School of Public Health – ECPE, Principles and Practice of Clinical Research (PPCR) Program, Boston, MA, USA; Institution Virtú Ophthalmology, Belo Horizonte, Brazil
Jorge Segovia
Harvard T.H. Chan School of Public Health – ECPE, Principles and Practice of Clinical Research (PPCR) Program, Boston, MA, USA
Jose Valenzuela
Harvard T.H. Chan School of Public Health – ECPE, Principles and Practice of Clinical Research (PPCR) Program, Boston, MA, USA
Letícia Sanches Kelemen
Harvard T.H. Chan School of Public Health – ECPE, Principles and Practice of Clinical Research (PPCR) Program, Boston, MA, USA; São Leopoldo Mandic, Campinas, Brazil
Lubna Mohammed
Harvard T.H. Chan School of Public Health – ECPE, Principles and Practice of Clinical Research (PPCR) Program, Boston, MA, USA
Maira Foresti
Harvard T.H. Chan School of Public Health – ECPE, Principles and Practice of Clinical Research (PPCR) Program, Boston, MA, USA
Maria Luiza Cunha D'avila
Harvard T.H. Chan School of Public Health – ECPE, Principles and Practice of Clinical Research (PPCR) Program, Boston, MA, USA; São Leopoldo Mandic, Campinas, Brazil
Marina Acevedo Zarzar de Melo
Harvard T.H. Chan School of Public Health – ECPE, Principles and Practice of Clinical Research (PPCR) Program, Boston, MA, USA; Oncologia D’Or, Recife, Brazil; Instituto Materno-Infantil de Pernambuco (IMIP), Recife, Brazil
Roma Aguiar
Harvard T.H. Chan School of Public Health – ECPE, Principles and Practice of Clinical Research (PPCR) Program, Boston, MA, USA
Tomislav Rajevic Mosler
Harvard T.H. Chan School of Public Health – ECPE, Principles and Practice of Clinical Research (PPCR) Program, Boston, MA, USA; Hospital del Trabajador ACHS Salud, Santiago, Chile
Yael Dinur Schejter
Harvard T.H. Chan School of Public Health – ECPE, Principles and Practice of Clinical Research (PPCR) Program, Boston, MA, USA; Division of IHOPE, Department of Pediatrics, Stollery Children’s Hospital, University of Alberta, Edmonton, Canada
Yannick Hurni
Harvard T.H. Chan School of Public Health – ECPE, Principles and Practice of Clinical Research (PPCR) Program, Boston, MA, USA; Department of Obstetrics, Gynecology and Reproduction, Dexeus Mujer, Dexeus University Hospital, Barcelona, Spain; Department of Paediatrics, Obstetrics, Gynaecology and Preventive Medicine and Public Health, Faculty of Medicine, Universidad Autonoma Barcelona, Barcelona, Spain
Abstract
Background: Overweight and obesity are major public health concerns. Increasing evidence links these conditions to cognitive decline and neurodegenerative disorders, potentially mediated by reduced brain-derived neurotrophic factor (BDNF). Intermittent fasting (IF) has gained attention for its potential metabolic and neuroprotective benefits, possibly increasing BDNF. However, the relationship between IF, BDNF, and cognitive outcomes in overweight and obese individuals remains unclear.
Purpose: This scoping review aimed to systematically map and synthesize the existing evidence on the impact of various IF protocols on BDNF levels in adults with overweight or obesity.
Methods: Following the PRISMA-ScR (Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension for Scoping Reviews) guidelines, a systematic search was conducted in five databases. Studies including adults with a body mass index ≥25 kg/m² and comparing various IF protocols to continuous caloric restriction or unrestricted diets were considered. The search included studies published up to April 26, 2025. Dual independent screening, data extraction, and risk of bias assessment (RoB 2.0) were performed.
Results: From 22,117 records screened, 6 RCTs (n = 534; 83.5% female; ages 18–70) were identified and mapped. Trials tested alternate-day fasting, time-restricted feeding, and intermittent energy restriction protocols over 8–32 weeks. The evidence mapping revealed that three studies demonstrated significant within-group increases in BDNF, with two also reporting greater increases versus controls; the remaining three trials found no effect. Two studies assessed cognition, but results were inconsistent and showed no clear benefit attributable to IF.
Conclusions: This scoping review mapped heterogeneous evidence suggesting that select IF protocols may elevate BDNF in overweight and obese adults; however, the available evidence exhibits considerable methodological heterogeneity, limiting definitive conclusions. Well-powered, rigorously controlled trials with standardized protocols are warranted to clarify the clinical relevance of BDNF modulation by IF.
