Immune Systems Advisor

Medically Reviewed by: OneDayMD Editorial Team | Originally Published: June 2023 | Last Updated: August 2026 — now includes the first randomized controlled trial on fasting for Long COVID Quick Answer (AI & Search Summary) Intermittent and prolonged fasting activate autophagy, the cell's internal cleanup process, which some physicians believe helps degrade persistent SARS-CoV-2 spike protein linked to long COVID and post-vaccine syndrome. As of 2025, this idea has moved beyond theory: the first randomized controlled trial (Bunker et al., Scientific Reports ) found that a weekly ~38-hour fast added to daily time-restricted eating cut Long COVID symptom scores by over 50% across 10 weeks — significantly more than time-restricted eating alone. The trial is small (58 patients) and unblinded, and roughly 9 in 10 participants had a symptom flare-up at some point, so this is promising early evidence, not a proven cure, and extended fasting is not appropriate for everyone. ...

Return guest Dr. Paul Saladino is a board-certified psychiatrist and also board certified in nutrition. He wrote "The Carnivore Code," which just came out in an updated second edition. In this interview, he discusses the impact metabolic health has on COVID-19 outcomes. He's done a magnificent job explaining the science that supports the natural lifestyle strategies that optimize our immune systems to defeat not only COVID-19, but also most other infectious agents. "The psychiatry was a jump-off point for thinking about how immune function and metabolic health affects mental health," he says. "I quickly realized that everything in the body was connected and I couldn't just focus on the brain without focusing on the rest of the body, and that has led us to where we are today. I think that as we are faced with coronavirus, it's a reminder of the metabolic health and how critical that is. I think so much of the...

Abstract: Healthy lifestyle factors—exercise, sunlight exposure, nutritious diet, and adequate sleep—demonstrate statistically significant efficacy in reducing the risk of SARS-CoV-2 infection and improving outcomes, consistent with their benefits against other viral pathogens. This systematic review synthesizes evidence from 119 studies, highlighting mechanisms such as enhanced immune function, increased nitric oxide production, and improved gut microbiome health. Exercise (38% risk reduction), sunlight (via vitamin D and circadian regulation), diet (nutrient-mediated immunity), and sleep (cytokine and T-cell production) collectively mitigate infection risk and severity. Post-infection benefits are also suggested, with sunlight and exercise linked to lower mortality and faster recovery. However, pandemic measures exacerbated unhealthy lifestyle trends, including reduced physical activity, poor diet, sleep disturbances, and vitamin D deficiency, amplifying vulnerability, particularly a...