Intermittent Fasting Warning: 8-Hour Eating Window Linked To 91% Higher Risk Of Death From Heart Disease

💡What to Know:

  • Diets focused on 16 hours of fasting and 8 hours of eating do not increase lifespan, researchers say.
  • Intermittent fasting restricts what a dieter eats to a small window of the day.
  • A person dies of cardiovascular disease every 33 seconds in the United States, according to the CDC.

CHICAGO — Intermittent fasting is a growing dietary trend embraced by health-conscious individuals who hope to improve their overall health and lifespan. New research, however, warns that one common form of the diet may actually worsen health down the road. Scientists say restricting your eating in an eight-hour time frame may significantly increase the risk of dying from cardiovascular disease, challenging previous beliefs about the diet’s heart health benefits.

Time-restricted eating is a form of intermittent fasting that confines daily eating to a set number of hours, often seen in the 16:8 method, where all meals take place within an eight-hour period followed by 16 hours of fasting. Proponents have touted its benefits for improving various health markers, including blood pressure, blood sugar, and cholesterol levels, making it a popular form of dieting.

The large-scale study involving over 20,000 American adults was presented at the American Heart Association’s Epidemiology and Prevention│Lifestyle and Cardiometabolic Health Scientific Sessions 2024 in Chicago.

“Restricting daily eating time to a short period, such as eight hours per day, has gained popularity in recent years as a way to lose weight and improve heart health,” says senior study author Dr. Victor Wenze Zhong, a professor and chair of the department of epidemiology and biostatistics at the Shanghai Jiao Tong University School of Medicine in China, in a media release. “However, the long-term health effects of time-restricted eating, including risk of death from any cause or cardiovascular disease, are unknown.”

Diet intermittent fasting
A dire new study warns that eating in an eight-hour time frame may significantly increase the risk of dying from cardiovascular disease, challenging previous beliefs about the diet’s heart health benefits. (© SASITHORN –

To assess these risks, researchers analyzed dietary patterns from the National Health and Nutrition Examination Surveys (NHANES) spanning 2003 to 2018, correlating these with mortality data up to December 2019. The study unveiled a startling 91-percent higher risk of cardiovascular mortality among individuals adhering to an eating window of less than eight hours compared to those who spread their meals across 12 to 16 hours.

This heightened risk was also observed in individuals with pre-existing heart disease or cancer. There was a 66-percent higher prospect of death from heart disease or stroke for those with an eating duration between eight to 10 hours daily. Researchers noted that eating over a period of more than 16 hours per day might reduce cancer mortality among those already diagnosed with the disease.

“It’s crucial for patients, particularly those with existing heart conditions or cancer, to be aware of the association between an eight-hour eating window and increased risk of cardiovascular death. Our study’s findings encourage a more cautious, personalized approach to dietary recommendations, ensuring that they are aligned with an individual’s health status and the latest scientific evidence,” explains Dr. Zhong. “Although the study identified an association between an 8-hour eating window and cardiovascular death, this does not mean that time-restricted eating caused cardiovascular death.”

Woman on diet eating broccoli on plate
The study unveiled a startling 91% higher risk of cardiovascular mortality among individuals adhering to an eating window of less than eight hours (© markoaliaksandr –

The study’s participant pool was diverse, including roughly equal numbers of men and women, but had a significant majority identifying as non-Hispanic Whites. The research, however, acknowledges limitations such as reliance on self-reported dietary information and the absence of factors outside daily eating duration that could impact health.

Dr. Christopher D. Gardner, the Rehnborg Farquhar Professor of Medicine at Stanford University, emphasized the need for further research, particularly regarding the nutrient quality of diets within different eating windows and demographic comparisons among participants.

“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,” says Dr. Gardner, chair of the writing committee for the Association’s 2023 scientific statement — Popular Dietary Patterns: Alignment with American Heart Association 2021 Dietary Guidance.

This study points to the complex nature of diet and its impact on health, suggesting that while time-restricted eating may offer short-term benefits, its long-term effects deserve careful consideration and further study.

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  1. 91%??? This is not true, it would have been spottet years ago if it were. Maybe the good dr. forgot to take into account that a lot of the cohort like had an italian breakfast (cigarettes and coffee) and not eating healthy the rest of the day. I bet if you look only at those with a healthy diet (and NOT selfreported) the numbers would be quite different.

    1. A study back in 2023 also found harm associated with intermittent fasting: “Our research revealed that individuals eating only one meal a day are more likely to die than those who had more daily meals,” says lead study author Yangbo Sun, from the Department of Preventive Medicine at The University of Tennessee Health Science Center, in a media release.”

      “Our research revealed that individuals eating only one meal a day are more likely to die than those who had more daily meals. Among them, participants who skip breakfast are more likely to develop fatal cardiovascular diseases, while those who skip lunch or dinner increase their risk of death from all causes,” study lead author Yangbo Sun explained.

      Sun Y, Rong S, Liu B, Du Y, Wu Y, Chen L, Xiao Q, Snetselaar L, Wallace R, Bao W. Meal Skipping and Shorter Meal Intervals Are Associated with Increased Risk of All-Cause and Cardiovascular Disease Mortality among US Adults. J Acad Nutr Diet. 2023

      1. The diet doctors obsess over eating sugary or simple starches that raise and lower our blood sugar, but then some of them are touting doing this and more, switching from eating to not eating and into keto daily? It makes no sense until you think about how they get paid and draw followers. Our capitalist market that makes our lives depend on being predatory to our fellow citizens needs some rethinking.

    2. Things like unhealthy eating habits or lifestyle habits would be the first things researchers would control for. I doubt that is the case. Besides people who engage in intermittent fasting would normally be the ones who are hyperconcerned about their diet and lifestyle habits. I wonder if people’s feelings and biases are what drives them to believe in one thing or another and try out these different fad diets? Intermittent fasting has a whole theory behind it going back to primitive times that we really know little about.

  2. In other words: People with cardiovascular and heart problems shouldn’t do intermittent fasting.

    Badly organized article.

    1. That is not what the research seems to indicate. But, yes, it probably would not be a great idea to try to cure cancer or heart disease with IF.

  3. No matter how many ‘experts and scientists’ you quote to support your ideas, I can find a greater number to repudiate them.
    The whole field of ‘nutrition’ is total BS. 5 billion Hindus over 4,000 years prove that vegetarianism is healthy, yet the carnivore diet and about a million eskimos show that you can exist on meat and blubber alone (at least for a considerable period of time).
    But one thing they all agree on, “It needs more study.” (ie give me money so that I don’t have to do any productive, useful work.)

  4. Diet is asymmetrical: you get a lot of benefit from avoiding the garbage like sugar and cheap seed oils. Trying to perfect diet doesn’t gain you a lot once you are avoiding the junk that retailers like to make so much $ from. Intermittent fasting is part of trying to perfect diet, people try to perfect all sorts of stuff and only add to the complexity and set themselves up as experts, no? The best reason to work on diet is for performance, how you will feel tomorrow, no?

    1. Bingo … it does seem like most of the problems modern people in the first world have is eating too much, and fake food that is processed. They manipulate our tastes and make it seem fine and healthy to eat junk that kills us, and since a large part of the economy hinges on our being led into bad habits, our government and systems are not exactly inventivized to seek or broadcast the truth. We have the worst kind of system that tried to lead us from one disaster into the next throughout the whole of our lives.

  5. I read medical journals for a living. 99% of current mainstream medical “research” is commercial, agenda- and narrative-driven.

    The mission of modern medicine is to make you sick. Not too sick that you croak, but sick enough to need lifelong treatment with pills, potions, lozenges, shots, cremes and ointments, and surgery.

    Medicine is 100% captured, on every level, by commercial interests. Since their interests and ours overlap only coincidentally, a good rule of thumb: Do the exact opposite of what they tell you.

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