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Time to go digging! Topic this time is Intermittent Fasting - what do we know?

Headlines are all a buzz about the dangers of intermittent fasting and its impact on our cardiovascular health. They are scary headlines indeed - more aptly put, they are thought provoking headlines which encourages us to dig deeper into the information. Although I could not find the actual study to which the headlines refer, I did manage to dig a bit and find more information about the study itself. What follows are not my opinions or ideas - they are direct quotes and all links are provided in bold/underlined green text.

What is the new headline? That Intermittent Fasting could lead to much higher risk of cardiovascular death.

The story behind the headline is what follows and I hope it will help to encourage us all to dig a little deeper when we hear something on the news.


About the study - this is from an article shared with me and from where my dig began!

The researchers analysed responses from around 20,000 adults who recorded what they ate for at least two days, then looked at who had died from cardiovascular disease after a follow-up period of eight years. The analysis also found there was an increased risk of cardiovascular death seen in people living with heart disease or cancer, and that among people with existing cardiovascular disease, an eating duration between 8-10 hours per day was associated with a 66% higher risk of death from heart disease or stroke. Researchers added their analysis suggested time-restricted eating "did not reduce the overall risk of death from any cause" and that having an eating duration of more than 16 hours per day was associated with a lower risk of cancer mortality among people with cancer.

More research needed, study leaders admit. The study, its researchers admit, has limitations, including its reliance on self-reported dietary information, which they say "may be affected by participant's memory or recall and may not accurately assess typical eating patterns. Factors that may also play a role in health, outside of daily duration of eating and cause of death, were not included in the analysis," they add.

Dr Zhong added it was too early to make specific recommendations about intermittent fasting based on his research alone but people should be "extremely cautious" about long-term fasting patterns. He said it was not clear why his research found an association between time-restricted eating and a risk of death from cardiovascular disease. He did theorise that people who limited their eating to fewer than eight hours per day may have less lean muscle mass than those who ate for 12 to 16 hours. Low lean muscle mass has been linked to a higher risk of cardiovascular death.

Dr Pam Taub, a cardiologist at UC San Diego Health - "It's a retrospective study looking at two days' worth of data, and drawing some very big conclusions from a very limited snapshot into a person's lifestyle habits." She added her patients have seen "incredible benefits" from fasting regimens, before concluding: "I would continue doing it. For people that do intermittent fasting, their individual results speak for themselves. Most people that do intermittent fasting, the reason they continue it is they see a decrease in their weight. They see a decrease in blood pressure. They see an improvement in their LDL cholesterol."


Lead author Victor Wenze Zhong, PhD, cautioned that the findings "require replication and we cannot demonstrate 8-hour TRE causes cardiovascular death in this observational study." Zhong noted that the study doesn't address the underlying mechanisms driving the observed association between 8-hour TRE and CV death.

Intermittent fasting is "certainly an interesting concept and one on which the potential mechanisms underlying the improvements in short outcome studies and preclinical studies in animals are strongly being pursued," Sean Heffron, MD, cardiologist at the Center for the Prevention of Cardiovascular Disease at NYU Langone Heart, New York, NY, who wasn't involved in the study.

Heffron expressed skepticism about the study results calling them "far from complete" and noted that data on diet was based on only 2-day diet records without correction for confounding variables.

Heffron also noted that the restricted diet group has more smokers and more men. "I would "strongly anticipate that once appropriate corrections are made, the findings will no longer persist in statistical significance," Heffron said. He emphasized the need for more rigorous research before making clinical recommendations.


The study’s limitations included its reliance on self-reported dietary information, which may be affected by participant’s memory or recall and may not accurately assess typical eating patterns.

Factors that may also play a role in health, outside of daily duration of eating and cause of death, were not included in the analysis.

Future research may examine the biological mechanisms that underly the associations between a time-restricted eating schedule and adverse cardiovascular outcomes, and whether these findings are similar for people who live in other parts of the world, the authors noted.

“Overall, this study suggests that time-restricted eating may have short-term benefits but long-term adverse effects. When the study is presented in its entirety, it will be interesting and helpful to learn more of the details of the analysis,” said Christopher D. Gardner, Ph.D., FAHA, the Rehnborg Farquhar Professor of Medicine at Stanford University in Stanford, California, and chair of the writing committee for the Association’s 2023 scientific statement, Popular Dietary Patterns: Alignment with American Heart Association 2021 Dietary Guidance.

One of those details involves the nutrient quality of the diets typical of the different subsets of participants. Without this information, it cannot be determined if nutrient density might be an alternate explanation to the findings that currently focus on the window of time for eating. Second, it needs to be emphasized that categorization into the different windows of time-restricted eating was determined on the basis of just two days of dietary intake,” he said.

“It will also be critical to see a comparison of demographics and baseline characteristics across the groups that were classified into the different time-restricted eating windows – for example, was the group with the shortest time-restricted eating window unique compared to people who followed other eating schedules, in terms of weight, stress, traditional cardiometabolic risk factors or other factors associated with adverse cardiovascular outcomes? This additional information will help to better understand the potential independent contribution of the short time-restricted eating pattern reported in this interesting and provocative abstract.


A personal thought from me on the headline - we really must KEEP READING - KEEP OUR MINDS OPEN TO NEW KNOWLEDGE AND NOT NEW HYPE. We simply must.

The above information is what I found with a little digging - literally in less than an hour I found these (and more!) articles about this headline. The headline is simply an abstract of a study with substantial and consequential limitations. There is need for further study to be sure - there is no need to interpret this abstract two-day study as the new science - this information has not been peer reviewed nor has it been replicated.

Moreover, the author himself tells us that this data is incomplete (though thought provoking) and requires further research. I am sure am glad I did a little digging on this one today! I wonder what you think about this topic - care to share your thoughts?


Be well


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