Could Intermittent Fasting Not Be Good For Your Heart In The Long Run?

I read a new analysis regarding fasting, specifically about intermittent fasting with an 8:16 hour ratio. This analysis was presented by Victor Wenze Zhong at an American Heart Association meeting. It was based on data extracted from the National Health and Nutrition Examination Surveys (NHANES), a U.S. database, for the years 2003-2018. It compared these data with those of individuals who passed away in the U.S. between 2003 and 2019, using another national database. The findings were published on March 18, 2024.

Just to give a briefly introduction, intermittent fasting is a dietary method that involves abstaining from food or its drastic limitation in specific time windows. The most popular and the one taken into consideration in the study is the 16:8 fast, which involves 16 hours of fasting followed by 8 in which all the main meals are organized. Previous research has found that this practice improves in the short term several values important for cardiometabolic health, such as blood glucose and cholesterol levels or blood pressure.

However, the long-term effects of this type of diet are less known and Dr. Zhong wanted to investigate further. Incredibly, they found that people who followed an 8-hour intermittent fasting regime were more likely to die from cardiovascular disease. This increased risk was also present for people already suffering from heart disease or cancer, and also, in this subgroup of patients, if the window of time for eating was extended from 8 to just under 10 hours: in this case the risk of death from cardiac events was increased by 66%. However, intermittent fasting did not appear - in the long term - to reduce the overall risk of early death from any cause.

I believe that, despite the importance of the American Heart Association meeting, it is important to note that the analysis is limited to reporting an association between this diet and cardiovascular risk; demonstrating no cause-effect link between the two things. Furthermore, from what I have read, it is not yet clear, for example, what the nutritional quality of the diet declared by the participants was, beyond the time window in which they ate.

In addition to these limitations, do you believe there could be others regarding the study? What can we do to improve this study and understand what the most important variables are to understand whether fasting is a healthy solution or not?