Time-restricted eating, or ‘intermittent fasting’ as it is commonly known, is as effective as calorie counting for weight loss, say researchers from the University of Illinois.
In a new study, obese adults who ate over a period of eight hours a day lost the same amount of weight as those who restricted calories but ate any time over ten or more hours a day.
The findings are published in the Annals of Internal Medicine.
Obesity is a significant health issue worldwide, and time-restricted eating has become a popular way to lose weight. Intermittent fasting is often easier to do than keeping a constant track of calories each day but whether it is an effective way to lose weight, especially over the long term, is still being determined.
To determine the value of intermittent fasting on weight loss, the researchers enrolled 90 racially diverse obese adults from the Greater Chicago area. Participants were divided into three groups to compare weight loss and different weight loss strategies.
One group of participants had an eight-hour time-restricted eating strategy which involved eating between noon and eight at night without counting calories. Another group reduced their daily calorie intake by 25 per cent, and a final group acted as a control group and did not change their eating habits, eating for ten or more hours a day. The time-restricted eating group could drink zero-calorie drinks outside the eight-hour eating window.
All participants initially met weekly with a dietician and continued to see them every two weeks until six months in the weight loss phase of the study. After that, participants saw the dietician every month up until twelve months. Body measurements were taken at the start of the study and at six and twelve months, and participants were asked not to change their exercise levels during the study.
Time-restricted eating was shown to be an effective way to lose weight when compared with the control group but was not more effective than calorie restriction for weight loss.
The time-restricted participants reduced their calorific intake by an average of 425 kilocalories per day. They also lost 4.6 kilograms more weight at twelve months than the control group, who did not change their eating habits. The calorie-restricted group reduced their daily calorie intake by an average of 405 kilocalories per day and lost 4.61 kg more weight at 12 months.
The researchers believe that access to dietitians helped participants in the restricted eating groups to lose weight and would like to see further work which could help determine who would most benefit from different dietary interventions.
Lead author of the study, Dr Shuhao Lin from the University of Chicago and her colleagues state that individual patient preferences need to be considered when offering obese patients dietary advice and hope that the results of this study will guide clinical decision-making in the future to determine the right weight loss program for each patient.