When people talk about fasting overnight, you might think of just not eating from bedtime until breakfast. But a 12-hour fast may have health benefits.
A study found that not eating for three hours before going to bed can aid blood pressure, blood sugar and pulse without cutting calories. The research came from Northwestern Medicine. It used people who were at risk for cardiometabolic concerns and had them stop eating three hours before bed. They saw improvements in their nighttime blood pressure by about 3.5 percent. Their pulse fell by about five percent. Their daytime insulin response and blood sugar levels improved.
“The results indicate that when timed to sleep, increasing the fasting duration to a minimum of 12 hours may be a practical and scalable approach to improve and maintain the cardiovascular health span,” said the study’s co-author, Dr. Phyllis Zee, the director of the Center for Circadian and Sleep Medicine at Northwestern Medicine.
The researchers stressed that they wanted their work to be practical. Dr. Zee said, “(The study) was designed to be practical – stop eating three hours before sleep, stop exposure to bright light, and extend fasting period to at least 12 hours and eat what you normally eat.”
Your body’s internal clock controls the metabolism, heart function, hormones and more, 24 hours a day. Keeping everything balanced is like a dance.
“Eating late, particularly when the body is winding down for sleep, can disrupt these natural rhythms,” said spokesperson for the Academy of Nutrition and Dietetics Angel Planells. “Finishing meals earlier may help keep digestion and metabolic processes aligned with the body’s sleep–wake cycle… During healthy sleep, heart rate and blood pressure naturally decline, a pattern known as ‘overnight dipping’ that supports cardiovascular health Avoiding late-night eating may help preserve this normal drop by allowing the body to fully focus on restorative processes rather than digestion.”
The study had some drawbacks. It was a short-term study. And it only used people with cardiometabolic risks. Plus, light exposure was also carefully controlled during the study, ensuring people were in dim light three hours before bed.
However, Mr. Planells is the first to point to how promising this new research is. And it is low risk to try to put it into action. He even had practical suggestions about putting the research into action in everyday life, as “It’s primarily about adjusting timing,” he said. “Finishing meals at least three hours before bedtime, opting for an earlier or slightly lighter dinner, and gradually shifting late-night snacks earlier by 15–30 minutes over time are practical ways to ease into the habit.”
“Timing our fasting window to work with the body’s natural wake-sleep rhythms can improve the co-ordination between the heart, metabolism and sleep, all of which work together to protect cardiovascular health,” said lead author, Dr. Daniela Grimaldi of Northwestern Univ. Feinberg School of Medicine.
