Dr. Michael Mosley, a well-known global nutrition expert, expressed his shock and surprise upon reading headlines indicating that the intermittent fasting diet, specifically the time-restricted eating (TRE) type, could have negative effects on the heart, potentially increasing the risk of deadly heart attacks, as reported by the British "Daily Mail." Dr. Mosley added that following the news, his phone was filled with messages and calls requesting him to "comment," as he, like many others, had incorporated various elements of intermittent fasting into his daily routine years ago to help manage his body weight and maintain appropriate blood sugar levels.
Dr. Mosley stated that over the past decade, he has spoken with many experts, read extensive research, and participated in studies that all demonstrated the benefits of intermittent fasting. He questioned whether the findings of the recent study could alter his views on the intermittent fasting diet. There are many different forms of intermittent fasting, including the 5:2 diet (where a person reduces calorie intake for two days a week) and time-restricted eating (TRE), where eating hours are simply reduced. Dr. Mosley explains that it essentially provides the body a break from digesting food to help stimulate "autophagy," a form of cellular "cleaning" that dismantles and recycles old cells.
He cited a review of significant research published in the New England Journal of Medicine in 2019, which stated that "intermittent fasting has widespread benefits for many health conditions, such as obesity, type 2 diabetes, cardiovascular diseases, cancers, and neurological disorders such as dementia." Dr. Mosley expressed confusion about the new research results suggesting that the 16/8 diet pattern (fasting for 16 hours and eating within an 8-hour window) is associated with a 91% increased risk of death from cardiovascular diseases and cancer.
He emphasized that after reviewing the summary of the new study, which is all that is currently available, he remains convinced that there is no cause for concern, particularly since the study relies on data from the U.S. National Health and Nutrition Examination Survey collected between 2003 and 2018. He explained that in these surveys, Americans were asked about their dietary habits, and the Chinese researchers selected those who marked that they restricted their food intake to eight hours or less on certain days. The researchers then compared these Americans to a national death index to see what happened to them.
It was found that these intermittent fasters were nearly twice as likely to die from heart diseases compared to those who did not adhere to such restrictions. There are many issues in trying to understand this study, not least because the age of the participants and their overall health status are unknown, as well as whether their memory was strong and accurate. More importantly, it is unclear whether the two days represented what they did the rest of the week.
As Kevin McConway, emeritus professor of applied statistics at the Open University pointed out: "We do not know if the eating times during those 24-hour periods were similar to the times they usually eat," making it seem unreasonable to link these patterns to deliberate, long-term, time-limited dietary interventions. Sir David Spiegelhalter, emeritus professor of statistics at the University of Cambridge, agreed with Professor McConway, adding somewhat pointedly: "This summary [of the new study] should not have been honored with a press release."
Other experts noted that individuals who reported eating only during an eight-hour period may have done so because they had previous heart issues or were working shift jobs, which is itself associated with an increased risk of heart disease and type 2 diabetes. Dr. Mosley added that there is no idea what those study participants consumed or whether it was a healthy Mediterranean diet or processed fast foods, affirming that his confidence in intermittent fasting remains unshaken by the summary of the new study findings.
Dr. Mosley advised those interested in continuing the TRE approach to heed the latest research findings, which indicate that it is better to consume more calories earlier in the day and avoid large evening meals. A study published in Nature Communications, involving 100,000 adults, found that eating breakfast before 8 AM and ceasing eating after 12 to 13 hours led to the greatest improvements in the risk of heart disease and type 2 diabetes. Eating after 9 PM was associated with a 13% increased risk of heart disease.
Dr. Mosley explained that the reason might be that intermittent fasting works best and yields good results in alignment with the body's biological clock and the production of hormones like insulin. He also recommended avoiding late-night eating (attempting to stop two to three hours before sleep), aiming for a "fast" of 12 to 14 hours, and adhering to a nourishing "Mediterranean" diet.
