Fasting diets are best for those who want to lose weight but hate calorie counting, according to a new study out of the US.
Celebrities including Jennifer Aniston, Gisele Bundchen, and Scarlett Johansson are fans of the restricted diet, which condenses food consumption into just a few hours each day.
Researchers from the University of Illinois at Chicago studied two time-restricted diets and found that they were effective at helping to significantly reduce body fat.
Results from the first-ever clinical trial of its kind compared the effects of two fasting diets - one which allowed participants to eat between the hours of 1pm and 5pm, and one that allowed eating between 1pm and 7pm.
During the fasting hours, participants were only allowed to water or calorie-free beverages, but were able to eat whatever they wanted during the four or six-hour eating period.
They were also told not to change their diet or physical activity levels for the duration of the trial, which lasted 10 weeks.
The study found that participants in both fasting groups reduced their daily calorie intake by more than 550 calories, and lost around three per cent of their body weight. But there was no difference in weight loss between the four-hour and six-hour fasting groups, the researchers concluded.
Insulin resistance and oxidative stress levels were also reduced, and there was no effect on blood pressure or cholesterol.
Professor Krista Varady said that six-hour fasting diets might be a better option for those who want to lose weight.
"The findings of this study are promising and reinforce what we've seen in other studies – fasting diets are a viable option for people who want to lose weight, especially for people who do not want to count calories or find other diets to be fatiguing," Varady explained. "These results suggest that the 6-hour fast might make sense for most people who want to pursue a daily fasting diet."