Caloric restriction and intermittent fasting alter spectral measures of heart rate and blood pressure variability in rats.
Level 5 - mechanism / opinion, no new human data
Animal experiment (preclinical bench research with no human data)
PubMed 16581971 · doi:10.1096/fj.05-5263com
What was done
Male Sprague-Dawley rats were implanted with telemetric transmitters to record beat-to-beat heart rate and diastolic blood pressure. Animals were maintained on either intermittent fasting (every-other-day feeding) or caloric restriction (40% caloric reduction). Power spectral analysis was used to assess cardiac autonomic activity by evaluating low-frequency and high-frequency oscillatory components of heart rate variability (HRV) and diastolic blood pressure variability (DPV).
What was found
No numerical values, sample sizes, or p-values were reported in the abstract. Both dietary restriction protocols decreased body weight, heart rate, and systolic and diastolic blood pressure. Both methods produced decreases in the low-frequency component of DPV spectra (a marker of sympathetic tone) and increases in the high-frequency component of HRV spectra (a marker of parasympathetic activity). These changes took at least 1 month to peak and reversed rapidly upon resuming ad libitum feeding.
Why it matters
The study indicates that both intermittent fasting and caloric restriction enhance parasympathetic tone and reduce sympathetic tone in rodents, providing a potential autonomic mechanism for the cardiovascular benefits of dietary restriction.
Limits
This is an animal study in male Sprague-Dawley rats, limiting direct translation to humans and female animals. The abstract provides no sample sizes, effect sizes, numerical values, or confidence intervals.
Cited by
- supports Intermittent fasting reduces resting heart rate and blood pressure.
- supports Intermittent fasting enhances parasympathetic nervous system activity and vagal tone to the heart in a manner similar to aerobic exercise.