8-Hour Time-Restricted Eating May Increase Risk


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Restricting eating to an 8-hour window each day may increase your risk of cardiovascular death. cometary/Getty Images
  • People who ate within a daily 8-hour window had a higher risk for cardiovascular death.
  • Those with heart disease or cancer also had a higher risk of cardiovascular death.
  • The study further found that this eating pattern was not associated with living longer.
  • Time-restricted eating could lead to metabolic effects that affect cardiovascular health.
  • A safer eating pattern might be one that involves moderation and healthy food choices.

According to research presented at the American Heart Association’s Epidemiology and Prevention │ Lifestyle and Cardiometabolic Scientific Sessions 2024, held from March 18-21 in Chicago, those who ate within an 8-hour window and fasted the rest of the time had a 91% higher risk of dying from cardiovascular disease.

The study further found that those with heart disease or cancer also had an increased risk.

Also, restricting eating to less than 8 hours per day did not lead to a longer lifespan.

These findings were in comparison with people who ate between 12-16 hours each day.

The study authors write that this type of intermittent fasting, known as time-restricted eating (TRE), has become quite popular.

It involves limiting yourself to eating only during a certain number of hours. For example, an 8-hour TRE plan could involve eating a late breakfast at 10 a.m. and completing the final meal of the day by 6 p.m.

While TRE does not involve counting calories, the belief is that people will naturally consume less, potentially helping them lose weight as well as providing them with other health benefits.

The researchers state that most short-term randomized controlled trials have found that TRE improves certain measures of cardiometabolic risk, such as blood pressure, cholesterol levels, and blood sugar. However, the long-term effects are not known.

Their goal for the study was to determine whether TRE is linked with a reduced risk of dying from all causes as well as from specific causes.

To gather information about the dietary patterns of the over 20,000 American adults who participated in the study, the team looked at data from the 2003-2018 National Health and Nutrition Examination Surveys (NHANES) and compared it to information about people who died between these years obtained from the Centers for Disease Control and Prevention’s National Death Index database.

In addition to the aforementioned findings regarding increased risk of death from cardiovascular disease, they found that people with existing cardiovascular disease who had an eating window of between 8 to 10 hours had a 66% higher risk of dying from either stroke or heart disease.

Also, TRE did not lessen the overall risk of death from any cause.

However, eating for less than 16 hours per day was linked with a lower risk of dying from cancer in those who had the disease.

The study authors stated in a press release that they were “surprised” by their findings since TRE has shown short-term cardiometabolic benefits.

“It’s crucial for patients, particularly those with existing heart conditions or cancer, to be aware of the association between an 8-hour eating window and increased risk of cardiovascular death,” said senior author Victor Wenze Zhong, Ph.D.

“Our study’s findings encourage a more cautious, personalized approach to dietary recommendations, ensuring that they are aligned with an individual’s health status and the latest scientific evidence.”

Trista Best, MPH, RD, LD, a Registered Dietitian at Balance One Supplements, said the increase in risk might be due to potential metabolic effects and dietary patterns.

“Restricting food intake to an 8-hour window could lead to overconsumption during the eating period, especially if individuals compensate by indulging in larger meals or unhealthy foods,” she explained. “This may contribute to metabolic dysregulation, including insulin resistance, elevated blood sugar levels, and increased inflammation, all of which are risk factors for cardiovascular disease.”

Best further noted that prolonged fasting can trigger stress responses in the body, which can elevate cortisol and impact cardiovascular health.

Following an “extreme eating pattern” could also lead to nutritional deficiencies or imbalances, further exacerbating cardiovascular risk factors, she remarked.

“Therefore, while intermittent fasting can offer benefits, such as weight loss and improved metabolic health when practiced appropriately, an 8-hour time-restricted eating window may pose risks if not followed mindfully and balanced with overall dietary quality and lifestyle factors,” Best concluded.

Catherine Rall, RD, a Registered Dietitian with Happy V, said “This study doesn’t actually show a causal connection between intermittent fasting and cardiovascular death, just a correlation.”

This means that while there is a statistical link between TRE and death, the study is not constructed in a manner that would allow us to definitively say that there wasn’t some third factor that actually caused these deaths.

“It also doesn’t control for any other underlying factors like what people were eating or what kinds of underlying health conditions people had,” she said.

Cardiologist Karishma Patwa, MD, who is with Manhattan Cardiology in New York City as well as a contributor to LabFinder, stated, “While we shouldn’t rule out TRE completely, the focus should always be on living a healthy lifestyle and indulging in moderation.”

As far as a specific way of eating, Patwa suggests the Mediterranean-DASH diet, which is also known as the MIND diet.

“The Mediterranean-DASH diet has been shown to reduce CV risk,” she said.

This diet offers a fusion between the Mediterranean diet and the DASH (Dietary Approaches to Stop Hypertension) diet.

Both of these eating plans emphasize consuming more fruits, vegetables, and whole grains.

They also suggest shying away from processed foods, added sugars, and excess sodium.

A study has found that people who ate their food for the day within an 8-hour window had a 91% higher risk for cardiovascular death.

People with cancer or heart disease were at greater risk for cardiovascular death as well.

The study further found that this eating pattern was not associated with living longer.

Time-restricted eating could lead to metabolic effects that affect cardiovascular health.

A safer eating pattern might be one that involves moderation and healthy food choices.


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