Can intermittent fasting double the risk of cardiovascular death? | BHF

Recently, news outlets reported that restricting eating time to eight hours a day and fasting for the remaining 16 hours may increase the risk of death from heart and circulatory disease. We reveal the truth behind the headlines.

Published March 22, 2024

Restricting the amount of time you eat during the day has become a popular way to lose weight in recent years. It's called time-restricted eating or intermittent fasting.

One of the most popular versions is 16:8 fasting. This means he only eats within an 8 hour window and fasts for the rest of his 16 hours.

Analysis of previous research endocrine reviews In the short term, our findings suggest that prolonged overnight fasting may improve blood pressure, blood sugar, and cholesterol levels. By controlling these factors, you can reduce your risk of heart and circulatory disease.

However, until now, the long-term effects of this type of intermittent fasting have not been studied.

This month, researchers at China's Shanghai Jiao Tong University presented early results of a study examining this question at a conference. american heart association meeting. Their report was widely covered in the British press. The researchers found a link between restricting eating and drinking time to less than eight hours a day and doubling the risk of death from heart and circulatory disease.

by Researcher presentation (PDF, 373KB, 1 page) People who restricted their eating to less than 8 hours a day had a 91 percent (nearly 2 times) increased. 12-16 hour window.

People who already had heart or circulatory disease at the start of the study were also more likely to die from heart or circulatory disease if they restricted their eating hours to eight to 10 hours. This increased her risk by 66%.

How successful was the research?

The study has not yet been “peer-reviewed”, meaning it has not been carefully checked by fellow researchers, and the full text has not been published.

Newspaper articles and TV reports about this are probably Presentation overview Or its press release. This means it's difficult to assess how accurate the research is.

First, an overview press release.

The brief states that a grace period of less than eight hours is associated with a 96 percent increased risk of death from heart and circulatory disease, compared to 91 percent in the press release.

The summary states that for people who already have heart or circulatory disease, an 8-10 hour eating window is associated with a 64 percent increased risk, compared to 66 percent in the press release. .

One good thing about this study is that it included a large and relatively representative group of people. Researchers followed nearly 20,000 U.S. adults with an average age of 49 years. Half of those surveyed were women, and 27 percent were not women. White.

To arrive at their results, the researchers looked at two questionnaires that study participants had previously completed as part of the U.S. survey. National Health and Nutrition SurveyI kept detailed records of what I ate over a 24-hour period.

They then calculated each person's average dietary window to see who died and from what causes during the average eight-year follow-up period.

A major limitation of this study is that participants were only asked about what they ate over a two-day period. We don't know whether those who reported restricting their meals to eight hours continued to do so throughout the study.

We also know that self-reported information about diet can be unreliable.

This study is also observational and cannot show cause and effect, only an association between two factors.

The study does not know whether time-restricted eating causes changes in the body that increase the risk of death from heart and circulatory disease. Alternatively, people who are more likely to die from heart and circulatory disease may also be more likely to go on time-restricted diets.

For example, some people may go on a 16:8 fasting diet because their doctor told them they needed to lose weight and we know that living with excess weight is a risk factor for heart and circulatory disease. There may be.

Alternatively, some people may report having limited mealtimes due to work commitments. Perhaps they are night shift workers or long-haul truck drivers. Alternatively, some participants may have skipped meals because they could not afford to eat. These work patterns and poverty are associated with an increased risk of heart and circulatory disease.

This study appears to contradict previous research that has suggested short-term benefits of intermittent fasting, and more research is needed in this area.

How good was the media coverage?

The study received widespread coverage in the British press, even though the full text was not published. daily mail, sky news, times, independent person and Sun.

The Times article was relatively balanced, covering study limitations and other reasons why a narrow diet may be associated with deaths from heart and circulatory disease.

The analysis concluded, “There is no solid evidence that you should stop intermittent fasting if it helps you maintain a healthy weight and makes you feel good doing it.” “Further research is needed,” he added.

Some of the other reports were highly inaccurate.

The Independent's headline “Shocking dangers of intermittent fasting diet revealed'' is false, as the study does not show that the diet causes deaths from heart or circulatory disease. The study simply showed an association with eating less than eight hours a day. You may die from heart and circulatory disease.

It also claimed that the study was published in the American Heart Association Journal, a peer-reviewed journal, but it was actually just a press release posted on the American Heart Association's website.

The Daily Mail also used the statistics from the press release, with the headline, “Fasting for more than 16 hours a day almost doubles the risk of death from heart disease in nearly 20 years of analysis,” highlighting the risks associated with intermittent fasting. This suggests that this is the direct cause of the increase. .

The headline also suggests that while the study followed participants for 20 years, it actually followed participants for up to 17 years, and on average for eight years.

The Sun newspaper led with the headline: “Skipping breakfast could double your risk of dying from heart disease, scientists warn.” There is no mention of skipping breakfast in either the study summary or the press release.

BHF judgment

Victoria Taylor, senior nutritionist at the British Heart Foundation, said: “This is not a full paper, so I cannot fully comment on the study. However, I do know that this is an observational study, so I can only provide links. It cannot be said that it is responsible for the differences seen in deaths from heart disease or circulatory disease.

“time-restricted meals It's an interesting but relatively new field. Therefore, further research is needed to draw firm conclusions about health-oriented dietary choices over a limited time period and long-term cardiovascular health.

“Some people choose this way of eating to lose weight, but it's not suitable for everyone. There's no one-size-fits-all approach when it comes to losing weight, so find what works best for you. It's important to find out.

“While research is still being conducted on when to eat, what we do know is that what you eat can make a difference to your risk of heart and circulatory disease.

“I eat the balanced diet It's something we can all do to improve our heart and circulatory health. This means incorporating lots of fruits and vegetables, legumes, nuts and seeds, fish and whole grains, and lowering sugar, salt and fatty foods throughout your diet. ”

What to read next…