It’s a diet trend endorsed by everyone from Hollywood stars to the current British Prime Minister.
But new research suggests that intermittent fasting may actually be harmful to long-term health.
Those who eat just eight hours a day are almost twice as likely to have a heart attack and stroke later in life, a study has found.
Experts said it showed why people should be careful about adopting trendy diets before the effects are fully known.
This study suggests that to reap the full benefits of fasting, a person may need to go without food for 72 hours – relying solely on water instead
Time-restricted eating, a form of intermittent fasting, involves limiting eating hours to four to 12 hours over a 24-hour period.
It has gained popularity in recent years, with the likes of British Prime Minister Rishi Sunak, Elon Musk and actress Jennifer Aniston suggesting it helps them keep fit.
Previous studies have linked time-restricted eating to improvements on several cardiometabolic health measures, such as blood pressure, blood glucose and cholesterol levels.
An early study of 20,000 adults found that those who followed a time-restricted eating plan were 91 percent more likely to die from cardiovascular disease.
The trendy diet plan did not reduce the risk of death from any cause, according to findings presented this week at the American Heart Association’s Lifestyle Scientific Sessions 2024 conference.
Researchers assessed dietary information from annual health surveys between 2003-2018 and compared it with mortality data over the same period.
Many who follow a time-restricted eating diet follow a 16:8 eating schedule, where they eat all their food in an 8-hour window and fast for the remaining 16 hours each day.
They found that this was linked to a greater risk of death from cardiovascular disease compared to people who eat during 12- and 16-hour windows.
Those with existing heart disease or cancer were at particular risk, they noted.
Professor Victor Wenze Zhong, from Shanghai Jiao Tong University School of Medicine, China, said: ‘We were surprised to find that people who followed an eight-hour time-restricted eating schedule were more likely to die from cardiovascular disease.
‘Although this type of diet is popular for its potential short-term benefits, our research clearly shows that, compared to a typical eating time of 12-16 hours per day, shorter eating duration was not associated with living longer. .’
The observational study did not take into account other possible contributing factors, such as participants’ weight and cholesterol, at the start of the study or during the eight-year follow-up period.
It relied on self-reported dietary information and other lifestyle factors, such as smoking and exercise, were not included in the analysis.
Commenting on the study, Keith Frayn, Emeritus Professor of Human Metabolism at the University of Oxford, said: ‘Time-restricted eating is popular as a means of reducing calorie intake, although proponents claim other benefits such as ‘boosting metabolism’ .
‘This work is very important in showing that we need long-term studies on the effects of this practice.
‘But this abstract leaves many questions unanswered and further research will be needed. ‘
Tom Sanders, emeritus professor of Nutrition and Dietetics at King’s College London, said that although popular, there is little evidence that fasting provides benefits for weight loss or weight maintenance.
He added: ‘We know from previous evidence that it is probably better to spread food intake over the day – small but often – rather than consuming large meals over a shorter period.
‘This is because after large meals there is a large increase in blood fats and glucose.’