iStockphoto / Rosendo Serrano Valera
The narrative on intermittent fasting is about to change in a huge way after the American Heart Association published a new study showing the popular 8-hour time-restricted dieting is associated with a 91% higher risk of a cardiovascular-related death.
What to know about the risks of 8-hour time-restricted intermittent fasting
The new research study was shared this week by the American Heart Association’s Epidemiology and Prevention council.
According to the study, they looked at data of 20,000 adults and found that those who followed an 8-hour time-restricted intermittent fasting diet “had a 91% higher risk of death from cardiovascular disease.” The average age of the study participants was 49-years-old and participants’ cardiovascular health were tracked between 8 and 17 years.
Unsurprisingly, the study also found that adults who were already battling cancer or heart disease had an increased risk of cardiovascular death.
The study acknowledged that previous research found the 16:8 eating schedule (8-hour intermittent fasting) was shown to “improve several cardiometabolic health measures” including cholesterol, blood glucose, and blood pressure.
That previous research showing the benefits of intermittent fasting has caused the diet trend to explode thanks to the ‘rise of the internet’ according to a past study on popularity. And those of us myself who eat like that most days due to our erratic schedules took solace in the fact that it was allegedly healthy.
What should the optimal eating window be?
The study found an 8-hour eating window led to a 91% increased risk in cardiovascular-related death. When the window is extended to 10 hours, the risk of dying from heart disease or stroke was still 61% higher.
According to the study, 16+ hours is the optimal eating window. The findings say “an eating duration of more than 16 hours per day was associated with a lower risk of cancer mortality among people with cancer.”
How am I or anyone expected to be eating from the moment we wake up until the moment we go to sleep? A 16+ hour eating window is hard for many of us to wrap our minds around.
Victor Wenze Zhong, Ph.D. is the senior author on the study. He shed some light on the discrepancy between previous research into intermittent fasting and this new study. Essentially, intermittent fasting can and does lead to short-term health benefits but is not associated with living longer.
He told Heart.org “we were surprised to find that people who followed an 8-hour, time-restricted eating schedule were more likely to die from cardiovascular disease. Even though this type of diet has been popular due to its potential short-term benefits, our research clearly shows that, compared with a typical eating time range of 12-16 hours per day, a shorter eating duration was not associated with living longer.”
The authors were quick to note that future research is now needed to explore the discrepancy between short-term and long-term health effects. Future research is also needed to address the study’s limitations, such as whether participants who were intermittent fasting were living higher-stress lifestyles.
This quote from Dr. Zhong really jumps out from the release. He said “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.”
Notice the emphasis on those with existing heart conditions or cancer. For individuals in those groups, a wider eating window is highly recommended at this point. Beyond that, the study offers a compelling case against the long-term benefits of intermittent fasting but still requires more research to definitively say it might not be right for an individual seeking the short-term benefits.