Fasting and Caloric Restriction in Long COVID Syndrome: A Scoping Review of Interventions and Outcomes.

Abstract

Background: Since the emergence of COVID-19, many patients continue to experience symptoms beyond the acute phase, a condition now termed long COVID syndrome (LCS). The complexity of LCS, with its varied symptoms, makes diagnosis and treatment challenging. Recent evidence suggests that dietary approaches, such as fasting and caloric restriction, may help in management of these symptoms. However, research on these interventions remains limited and preliminary.

Objectives: In this review we aimed to explore existing studies on the impacts of fasting and caloric restriction for LCS management, focusing on how these approaches might alleviate symptoms through mechanisms like reduced inflammation, enhanced autophagy, and better metabolic health. Additionally, we examined intervention types, reported outcomes, and gaps in the research to guide future studies of LCS.

Methods: A systematic search was conducted using databases like PubMed, Scopus, and ScienceDirect for studies published from 2019 to 2024, following the Arksey and O'Malley framework and Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) guidelines. A range of study types, including case series, narrative reviews, randomized controlled trial protocols, and public guidance documents, were included. Data were descriptively compiled.

Results: Eleven studies met inclusion criteria, covering interventions such as intermittent and prolonged fasting, as well as caloric restriction, with durations from days to weeks. Some reported benefits included reductions in fatigue, cognitive impairment, and inflammatory symptoms such as joint pain, muscle pain, or chest tightness. However, the findings reported here are preliminary and limited by small sample sizes, short follow-up, and varied protocols and outcomes, underscoring the need for further standardized research.

Conclusions: Fasting and caloric restriction have shown potential benefits in managing LCS symptoms like fatigue, cognitive decline, and inflammatory symptoms. Nonetheless, the diversity of study designs and outcomes necessitates more rigorous research to confirm the effectiveness and safety of interventions for LCS management. Future studies should focus on long-term effects and biological mechanisms and include broader, more diverse populations to enhance generalizability and support clinical guidance.