Rachel McDonald
Rachel McDonald is a journalist and media officer at the Australian Science Media Centre.
Claims time-restricted eating is linked to a 91% increased risk of heart-related death may have jumped the gun, according to UK experts.
This week, the American Heart Association issued a press release about research being presented at EPI|Lifestyle 2024, a lifestyle and cardiometabolic research conference in Chicago. The research, currently available as a poster presentation and short abstract, says the popular diet tactic of time-restricted eating is associated with a major increased risk of death from heart disease over a long-term period.
Time-restricted eating, similar to intermittent fasting, involves eating all the food you plan to eat in a day within a six to eight hour period, and fasting for the other 16 to 18 hours. The study involved 20,000 adults providing data on what they ate, and at what times, over a 24-hour period on two separate occasions from 2003 to 2018. In 2019, the researchers looked at the death rates within the cohort to make their conclusions.
All six independent experts who spoke to the UK Science Media Centre about this study said it was difficult to determine how well this study was conducted without access to the full paper, which is yet to be fully peer-reviewed. However, Emeritus Professor Sir David Spiegelhalter from the University of Cambridge went as far as saying the abstract “should not have been graced with a press release.”
Emeritus Professor Kevin McConway from Open University agreed the abstract should not have been promoted with a press release and said there were aspects of the abstract that showed the research may have some limitations.
“The researchers classified people into different dietary patterns on the basis of what and when they reported they ate in just two days, over a study period averaging 8 years. We don’t know whether their eating times over those two 24-hour periods was typical of the times they usually ate. So to relate those patterns to a deliberate long-term time-restricted eating intervention seems to be going far beyond the data,” McConway says.
Read more: What is a diet?
If the participants were deliberately participating in time-restricted eating, Prof McConway said it was hard to tell if other factors were at play that contributed to the high heart disease death risk in the group.
“People who were already worried about their cardiovascular health, perhaps for some good reason such as signs of illness or previous unhealthy activity, might be more likely to decide to restrict their eating times. Increases in cardiovascular deaths in people who restricted their eating times, might be explained by whatever was causing the previous worries, rather than the diet restriction. We just can’t tell.”
Emeritus Professor Tom Sanders from King’s College London shared these concerns, but says the research did also appear to have some strengths with a relatively long follow-up period and a large cohort of people studied.
Sanders says in general, evidence showing the benefits of time-restricted eating on weight loss and maintenance was lacking, and previous research suggested it may not be the best for your heart.
“Regarding cardiovascular risk factors, we know from previous existing evidence that it is probably better to spread food intake out throughout the day (small but often) rather than consume large meals over a shorter period.”
Emeritus Professor Keith Frayn from the University of Oxford said while there were unanswered questions when it came to this study right now, long-term research on time-restricted eating such as this study is needed.
“In general, we should be cautious about widespread adoption of eating strategies that have not been properly evaluated for longer-term effects.”
You can read the UK SMC Expert Reaction here