The Study
Effects of long-term fasting and confinement on the cardiovascular activity
This study watched what happened to 13 people when they fasted and stayed in a small space versus a normal one. It found that their hearts behaved differently, but it didn't randomly assign who went where — so we can't say the space caused the changes, just that they happened together.
Analysis score
Maximum 90 for a randomized controlled trial.
Where the score came from
When people fast for 10 days, their heart slows down and their body changes its electrolytes. If they also stay locked in a room, their heart gets even calmer—but these changes might be risky.
Where does this study sit?
Reviews of RCTs (Meta-analyses)
Max 100Randomized Trials
Max 90Reviews of Cohort Studies
Max 85Cohort Studies
Max 72Reviews of Case-Control Studies
Max 63Case-Control Studies
Max 58Cross-Sectional & Case Series
Max 50Expert Opinion
Max 537 / 100
Quality score
Participants are randomly assigned to treatment or control groups, minimizing bias. The gold standard for testing whether an intervention causes an effect.
Key takeaways
Summary
Based on the study abstract and findings.
- 1A longer QTc interval can trigger dangerous heart rhythms, and low sodium or high calcium can make this worse—so fasting, especially when confined, might be risky for the heart.
- 2Heart rate dropped by over 10% (p < 0.01).
- 3Sodium in blood fell (p < 0.01), calcium rose (p < 0.05), and heart's electrical recovery time (QTc) got longer (p < 0.05).
Score breakdown, methodology, conflicts of interest, evidence analysis & raw study data
Publication
Journal
Medical & Biological Engineering & Computing
Year
2021
Authors
Yang Liu, Qince Li, Kuanquan Wang, Runnan He, Z. Dai, Hongyu Zhang, Chengyu Liu, Qianying Ma, Yongfeng Yuan, Chengjia Yang, Yinghui Li, Henggui Zhang
Related Content
Claims (6)
Fasting for 12 to 16 hours is associated with higher heart rate variability and lower resting heart rate, while fasting for more than 48 hours is associated with lower heart rate variability.
During long-term fasting, individuals who are confined show higher heart rate variability metrics (pNN50, rMSSD, Ln-HF) and a slower resting heart rate than those who are not confined.
People who fast for a long time while being confined show measurable differences in heart rate variability and heart rate compared to people who fast for the same duration without confinement.
In healthy adults, prolonged fasting is linked to lower blood sodium, higher blood calcium, and a longer QTc interval on heart monitors, which are physiological changes associated with increased risk of irregular heart rhythms.
People who fast for extended periods have lower systolic blood pressure compared to those who do not, regardless of whether they are confined or not.
Prolonged fasting is linked to a longer QTc interval on an electrocardiogram, which is a measurable electrical delay in the heart's pumping cycle that raises the risk of dangerous irregular heartbeats, regardless of whether a person is confined or not.
Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.