Experts Question Findings of Study Linking Intermittent Fasting to Higher Heart Risks

Intermittent fasting, previously known as a trendy method of weight loss, is now being considered potentially harmful to heart health. An increased risk of death due to cardiovascular diseases has been linked to this dietary approach.

The American Health Association mentioned this concern on March 18, based on their findings from a study. The data came from a conference held by the association and has not been published in a vetted scientific journal. However, these immediate findings have drawn skepticism from health experts who outlined its limitations.

The idea behind intermittent fasting is varying periods of eating and fasting. The association's study mainly looked into time-limited eating, which confines the daily eating window. An increased 91% risk of death due to cardiovascular diseases was spotted in people who followed a 16:8 diet, or consumed food only within an eight-hour timeframe, compared to those who ate across 12 or 16 hours. The lead researcher, Victor Wenze Zhong - a professor at the Shanghai Jiao Tong University School of Medicine, mentioned that it was essential for patients, especially those with existing heart or cancer conditions, to consider the increased risk of cardiovascular death linked to the 8-hour eating timeframe.

However, Heba Wassif, a Cardiologist from the Department of Cardiovascular Medicine at the Cleveland Clinic not involved in this research, warned against giving too much importance to the findings. As per her, the long-term effects of time-restricted eating remain ambiguous due to insufficient information. She and several others have also advised caution in interpreting the results of the study.

The study used data from over 20,000 American adults participating in the National Health and Nutrition Examination Survey between 2003 and 2018. The survey was created to evaluate the health and nutritional circumstances of adults and children in the U.S.

The participants, comprising almost equal numbers of men and women, were predominantly White, with an 11% Hispanic, 8% Black, and remaining being from other racial categories representation.

The survey participants disclosed their food consumption and eating patterns for study purposes on two distinct days. The researchers observed them for an average of eight years.

It was found that people with existing heart conditions who ate solely within an eight-hour timeframe had a 66% higher risk of dying from a heart ailment or stroke. Cancer patients also had an increased risk of dying from heart diseases. However, no connection between time-restricted eating and longer life expectancy was found.

Zhong clarified that the study only showed a link between intermittent fasting and the risk of cardiovascular death and did not indicate that fasting directly elevated the risk.

Paul Leis, an Assistant Professor of Medicine at the Icahn School of Medicine, termed the findings as "an interesting observation" but noted that the study was significantly flawed. He claimed the survey relied heavily on self-reported information, which might be unreliable. It also failed to provide adequate details about the underlying health conditions of the participants.

Leis continued his criticism by questioning the absence of crucial details such as diabetes, cardiovascular diseases, other diseases, physical exercise, and BMI among participants. He wished this data had been made available. He also raised concerns about the types of food the participants had been consuming during the 8-hour dining window.

Stephen Kopecky, a cardiologist at the Mayo Clinic, raised similar concerns about the quality of food intake, suggesting that limited time could lead to consumption of ultra-processed meals, increasing mortality risk and potential cancer spread.

Wassif expressed surprise at these findings since prior studies had found this type of diet beneficial.

Indeed, some research has suggested that intermittent fasting may improve health by lowering blood pressure, inflammation, and cholesterol.

And according to Leis, there’s evidence to show it can help with weight loss.

“When people fast, you end up using your glycogen stores and then you switch over to ketosis, breaking down fatty acids for energy,” he explained. “There is data to support that due to this reset, you end up losing weight.”

Leis thinks there’s “a role for intermittent fasting to benefit those at high risk for cardiovascular disease,” but recommends that anyone thinking about starting intermittent fasting consult a doctor to figure out which plan—if any—is right for them.

“Maybe the 16:8 method doesn’t work for you but the 12:12 does,” he added. “Patients should discuss with their doctor to see what fits with their profile.”