COVID-19: healthy lifestyles reduce risk

• Healthy lifestyles reduce COVID-19 severity

@CovidAnalysis, November 24, 2025
c19early.org
Efficacy confidence - lifestyles
Dietp<0.00000001
Exercisep<0.00000001
Sleepp<0.00000001
Sunlightp=0.00005
Efficacy confirmed October 2020 (exercise)(a),1
P-values indicate the confidence that studies show a significant effect. p=0.05 is the typical threshold for significance, with lower values indicating higher confidence. See the individual analyses for details of efficacy for specific outcomes and conditions.
Healthy lifestyles reduce risk Across 119 studies, exercise, a healthy diet, improved sleep, and sunlight show significantly lower risk for SARS-CoV-2, just as they do for other viruses2-5. They all have connections to other effective treatments:
•Sunlight6-11 increases nitric oxide and vitamin D, helps regulate the circadian rhythm which supports immune health, may increase melatonin production at night, and directly inactivates SARS-CoV-212.
•A healthy diet13-43 contains many nutrients shown to be beneficial, enhances immune system function, and supports a healthy gut microbiome.
•Improved sleep40,44-59 aids the absorption, metabolism, and utilization of nutrients, and improves immune system function. During sleep, the body produces and releases cytokines that help fight infections and reduce inflammation, and sleep enhances T cell function and their ability to form immune memory.
•Exercise40,57,60-126 increases nitric oxide, reduces chronic inflammation, improves cardiovascular health, improves comorbidities, and enhances lung function.
Lifestyles may reduce risk even after infection Most studies examine outcomes based on lifestyles before infection. What about during infection? Logically, healthy lifestyles may still be beneficial, especially prior to later stage disease, and within limits(b). One study predicts lower mortality for increased sunlight exposure before 7 days after infection127. In hospitalized patients, studies show lower mortality with exercise60, and faster recovery with near-infrared light6.
Pandemic measures harmed lifestyles 25 of 25 studies in a meta analysis showed a decrease in physical activity during the pandemic128. Those at high risk were more likely to be physically inactive129. There were unfavorable changes in diet130,131 and sleep131,132. Lockdowns increased vitamin D deficiency133,134. A review showed negative effects for mental health, physical activity, and obesity135, and those with poor health status may have been more likely to have unfavorable lifestyle changes, compounding risk136. Fear, stress, and loneliness increase risk for poor COVID-19 outcomes137. Inaccurate depictions of risk and available treatments, along with public health measures involving isolation, may have compounded risk among the most vulnerable. The pandemic was associated with increased weight and higher prevalence of hypertension in adolescents in the USA138, and a substantial increase in global hunger and malnutrition139. Overweight and underweight both increase risk for COVID-19140.
 
Footnotes
a.
Defined as ≥3 studies showing ≥10% improvement or >0% harm with statistical significance in meta analysis.
b.
For example, vigorous exercise may be harmful depending on condition.
References
139.
who.int, www.who.int/news/item/06-07-2022-un-report--global-hunger-numbers-rose-to-as-many-as-828-million-in-2021.