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Late-night cravings might be doing more than just ruining your diet.
New research from the Northwestern Feinberg School of Medicine suggests that heart health isn’t just about what’s on your plate — it’s also about when you eat.
The study pinpointed the optimal cutoff for evening meals, finding that participants who followed it had lower blood pressure, steadier blood sugar and improved heart rates.
“Timing our fasting window to work with the body’s natural wake-sleep rhythms can improve the coordination between the heart, metabolism and sleep, all of which work together to protect cardiovascular health,” Dr. Daniela Grimaldi, first author of the study, said in a statement.
Let’s just say, Americans could use it. Across the country, only 6.8% of US adults had optimal cardiometabolic health in 2018 — or less than 1 in 14 people.
Poor cardiometabolic health is strongly linked to a higher risk of chronic illnesses such as Type 2 diabetes, heart disease, kidney failure, sleep apnea and certain cancers, as well as premature death.
In the study, Grimaldi and her colleagues recruited 39 adults, ages 36 to 75, who were overweight or obese.
The participants were divided into two groups: One followed an extended overnight fast of 13 to 16 hours, finishing their last meal three hours before bedtime, while the other stuck to their usual 11- to 13-hour fast.
Both groups were instructed to dim the lights three hours before hitting the hay. Notably, 80% of the extended fasting group were women.
After seven-and-a-half weeks, the results were striking. Participants who finished eating three hours before bedtime saw “meaningful improvements” in critical markers of heart health compared to those who followed their usual routine.
On average, their blood pressure dropped by 3.5% and their heart rate fell by 5% at night, a natural dip during sleep that researchers say is an important sign of cardiovascular health.
Their hearts also followed a healthier rhythm, speeding up during the day and slowing while they slept.
The group that stopped eating three hours before bedtime also had better daytime blood-sugar control, with their pancreases responding more efficiently to glucose.
In other words, their bodies were finally syncing with their natural sleep cycle, giving both heart and metabolism a boost.
That’s a notable finding, since past research on time-restricted diets has primarily focused on how long people fast, not how their fasting aligns with their sleep schedule.
“It’s not only how much and what you eat, but also when you eat relative to sleep that is important for the physiological benefits of time-restricted eating,” Dr. Phyllis Zee, corresponding author of the study, said in a statement.
By the end of the study, nearly 90% of the participants had stuck to the time-restricted eating schedule, suggesting it’s a plan people can actually follow.
There’s a bonus, too: Avoiding late-night meals may help with weight management, even if total calorie intake stays the same.
A 2022 study of 16 overweight or obese young adults compared “early” and “late” meal schedules, with participants eating the same foods and exercising the same amount.
The study found that those who ate later in the day felt hungrier, had lower levels of an appetite-reducing hormone, stored more fat and burned less throughout the day.
The Northwestern researchers say their approach — using sleep as a guide for when to stop eating — could be an easy, drug-free way to boost cardiometabolic health, especially for middle-aged and older adults at higher risk.
Looking ahead, the team plans to refine the protocol and test it in larger, multi-center trials to see if the benefits hold up on a broader scale.
