Researchers from Northwestern University (USA) studied how aligning overnight fasting with the natural sleep-wake cycle can improve heart health and metabolism. Importantly, the participants did not reduce their calorie intake, but merely adjusted their meal timing.
Dr. Christine Bakke Westergaard noted that properly scheduling fasting periods in accordance with natural sleep-wake rhythms helps coordinate the heart, metabolism, and sleep, which collectively contributes to cardiovascular health. This study showed that synchronizing meal timing with circadian rhythms can significantly improve cardiometabolic health.
The study lasted 7.5 weeks and involved 39 overweight or obese adults aged 36 to 75 years. Participants were divided into two groups: one group engaged in an extended overnight fast (13–16 hours) and the other, a control group, engaged in a normal fasting regimen (11–13 hours). All participants dimmed the lights three hours before bed.
When to finish dinner
The results showed that those who followed the overnight fasting regimen improved several indicators. Nighttime blood pressure decreased by 3.5%, and heart rate by 5%. These changes indicate a healthier circadian rhythm, in which blood pressure and heart rate decrease at night, which contributes to improved cardiovascular health.
“We hypothesized that a tailored intervention that increases overnight fasting duration by 3 hours (last meal ≥3 hours before bedtime) would improve nocturnal autonomic balance, reduce blood pressure and heart rate, enhance blood pressure reduction, and improve glucose regulation compared with a control group maintaining a habitual diet,” the authors write.
Participants in the experimental group also showed improved blood sugar control. The pancreas responded more effectively to glucose, confirming improved insulin production and stable blood sugar levels.
Simply put, it's best to have 13-16 hours between dinner and breakfast. Your last meal of the day should be at least 3 hours before bedtime , and preferably earlier.
This study confirms the importance of not only what we eat, but also when we eat. The results were published in the journal Arteriosclerosis, Thrombosis, and Vascular Biology.