Intermittent fasting is a relatively new concept and most of what has been reported has been in terms of results are anecdotal stories and results from small trials. Now the largest UK community science study of its kind shows consistently eating in a 10-hour window during the day is associated with higher energy and mood and lower hunger levels.
Kings College London researchers studied the subject and recently presented their findings at the European Nutrition Conference in Belgrade, Serbia.
Intermittent fasting, or what some call time restricted eating, is when you limit your eating during the day to a certain amount of time and the rest of the day and through the night is considered fasting time. It has been shown effective for losing weight and controlling blood sugar in other smaller studies.
With a 10-hour eating window you limit your food consumption to between 9 a.m. and 7 p.m., for example, with nothing before or after. That would leave you with 14 hours of fasting time.
While there are some that prescribe a more restrictive window of eating, as little as four hours per day, the study found there are significant benefits even with a less restrictive window of 10 hours. The key is to not eat or drink anything the rest of the time that will break your fast and raise your blood sugar.
The study consisted of more than 37,000 people who used the ZOE Health app. They participated in a three-week program that started with a week of unrestricted eating followed by two weeks of limiting their intake to a 10-hour window.
The study found those who had a consistent schedule achieved greater results than those who varied their eating window from day-to-day. And those who had a larger eating window before the trial saw even greater benefits when sticking to a 10-hour routine.
"This is the largest study outside of a tightly controlled clinic to show that intermittent fasting can improve your health in a real world setting," said Dr. Sarah Berry, from King's College London and chief scientist at ZOE. "What's really exciting is that the findings show that you don't have to be very restrictive to see positive results: a ten-hour eating window, which was manageable for most people, and improved mood, energy levels, and hunger. We found for the first time that those who practiced time-restricted eating, but were not consistent day to day, did not have the same positive health effects as those who were dedicated every day."
More than 95 percent of the study participants opted to add more weeks to their fasting routine.
"This study adds to the growing body of evidence showing the importance of how you eat,” said Kate Bermingham Ph.D., from King's College London and ZOE. "The health impact of food is not just what you eat but the time at which you choose to consume your meals, and eating window is an important dietary behavior that can be beneficial for health. Findings shows that we don't need to be eating all the time. Many people will feel satiated and even lose weight if they restrict their food to a ten-hour window."