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Is Intermittent Fasting Bad for Your Heart?

Is Intermittent Fasting Bad for Your Heart?

This content originally appeared on On a regular basis Health. Republished with permission.

By Becky Upham

Key Takeaways

  • A study presented this week at a serious cardiology conference linked time-restricted eating with an increased risk of cardiovascular death.
  • The study was based on two days of self-reported dietary data, with a median of eight years of follow-up.
  • Limitations of the study make it hard to attract sweeping conclusions, other researchers say.

Individuals who follow a type of intermittent fasting called time-restricted eating — specifically, those that only devour calories during an eight-hour window every day — almost double their risk of dying from heart problems compared with individuals with a typical 12 to 16 hour window, in line with preliminary research presented at an American Heart Association conference happening this week in Chicago.[1]

“We were surprised” by these findings, says senior study creator Victor Wenze Zhong, PhD, a professor and chair of the department of epidemiology and biostatistics on the Shanghai Jiao Tong University School of Medicine in Shanghai, China, in a press release.[2]

The outcomes are definitely attention-grabbing. However it’s essential to notice that that is an observational study so it didn’t find that time-restricted eating causes cardiovascular death, but that there may be an association.

There are additional caveats that put the outcomes of the study into query, says Christopher D. Gardner, PhD, professor of medication at Stanford University in California, and a number one nutrition researcher who was not involved on this study.

As an illustration, Dr. Gardner wonders: What sorts of foods did people within the study eat? Since the evaluation hasn’t yet been published in a peer-reviewed medical journal, essential details aren’t available yet.

“I find the concept of time-restricted weight-reduction plan problematic basically because the main target stays on when foods are consumed somewhat than the standard of what’s being consumed,” Gardner says. “As a nutrition scientist, I’m more concerned with the standard of what people eat.”

Earlier Research Showed Time-Restricted Eating Can Improve Measures of Heart Health within the Short Term

Time-restricted eating involves consuming calories only during a particular range of hours every day, generally starting from a 4- to 12-hour time window.

People may follow a 16:8 schedule, fasting for 16 hours a day and getting all their calories in an eight-hour window — from 7 a.m. to three p.m., say, or 11 a.m. to 7 p.m.

Previous research, which has mostly been limited to a comparatively short follow-up of 1 month to 1 yr, has found that time-restricted eating improves several cardiometabolic health measures, including blood pressure, blood glucose, levels of cholesterol, and obese or obesity.[3]

The Recent Study Followed 20,000 Adults for a Median of 8 Years

The brand new study used information collected for years — eight years was the median length of follow-up, with a maximum of 17 years — from roughly 20,000 U.S. adults participating within the annual 2003–2018 National Health and Nutrition Examination Surveys.

Soon after enrollment, participants accomplished two questionnaires that asked them to recall what they’d eaten inside the previous 24 hours. Researchers placed people into considered one of five categories in line with the length of their eating window, starting from lower than 8 hours to 16 hours.

The scientists then circled back with the topics for years to trace their health.

After controlling for various aspects, including age, race, and ethnicity, and history of disease, the researchers concluded that:

  • Individuals who restricted their eating window to lower than eight hours per day had a 91 percent higher risk of death as a consequence of heart problems (mainly heart disease and stroke) compared with individuals with a window of 12 to 16 hours.
  • Amongst individuals with existing heart disease, an eating window of 8 to 10 hours per day was related to a 66 percent higher risk of death from heart problems.
  • Time-restricted eating didn’t reduce the general risk of death from any cause.

Study Has Limitations That May Call the Findings Into Query

Nutrition experts asked to comment on the brand new research point to limitations within the study setup that will call the outcomes into query.

“I believe the conclusions are extremely overstated considering that the investigators only have two days of dietary intake data over a 20-year period — what were the topics eating on the opposite 7,300 days of the study?” says Krista Varady, PhD, professor of kinesiology and nutrition on the University of Illinois in Chicago. Dr. Varady, who was not involved within the study, has done extensive research on intermittent fasting for weight reduction and metabolic disease reduction in individuals with obesity.

Gardner also finds it problematic to group people into eating window groups based on just two days of information. “Higher than at some point, but it surely remains to be likely that many individuals within the study were misclassified. Higher would have been multiple days in the primary yr, after which additional eating regimen data from subsequent years,” he says.

Dr. Zhong acknowledges this as a crucial limitation of his study, but notes that the evaluation excluded individuals who reported an atypical eating regimen on either of the 2 days.

Aspects Resembling Stress Level and Access to Food Could Play a Role

There are various aspects that would have influenced the chance for heart disease amongst subjects within the study, though these could also be addressed once the complete evaluation is published, says Gardner.

“For instance, what if those eating in a shorter time period had less access to food, worked more work shifts, and experienced more life stress compared with those within the 12 to 16 hour category?” Gardner says. That may mean the findings about cardiovascular deaths might be attributable to something aside from the smaller eating window.

Researchers Agree: More Studies on Time-Restricted Eating Are Needed

“It’s too early to offer a particular suggestion on time-restricted eating based on our study alone,” says Zhong. Still, he says his findings suggest that eating this fashion for years ought to be approached with caution, he says.

Reasonably than following a time-restricted eating regimen, he believes it’s higher to follow a eating regimen with proven health advantages, comparable to the DASH eating regimen and Mediterranean eating regimen. “Based on the evidence as of now, specializing in what people eat appears to be more essential than specializing in the time once they eat,” Zhong says.

Gardner shares that opinion. But he does imagine that time-restricted eating may profit some individuals who find it helps them psychologically.

He notes that many individuals find it hard to make mostly healthy selections in the present food environment in the US where low-quality foods are inexpensive, highly available, highly palatable, and highly convenient, he says.

“I’m convinced that for some people a time-restricted eating regimen proves helpful — from a behavioral psychology perspective,” says Gardner.

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  1. Association Between Time-Restricted Eating and All-Cause and Cause-Specific Mortality. American Heart Association. March 18, 2024.
  2. Eight-Hour Time-Restricted Eating Linked to a 91 Percent Higher Risk of Cardiovascular Death. American Heart Association. March 18, 2024.
  3. Gabel K et al. Time-Restricted Eating to Improve Cardiovascular Health. Current Atherosclerosis Reports. March 26, 2021.


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