Study: Daily Fasting for This Long Results in Weight Loss and Better Mood

Updated: Feb. 04, 2024

It might sound difficult, but research indicates that limiting your eating to certain hours of the day can have major health benefits—including reducing hunger, and improving mood and sleep.

Intermittent fasting, also known as time-restricted eating (TRE), can be intimidating. Questions about perpetual hunger and the ability to engage in various activities often arise, especially during the holiday season when food takes center stage at many gatherings. In general, it’s crucial to adopt an eating pattern that aligns with your lifestyle while promoting good health. Researchers for a recent study claim to have identified an effective and easily achievable form of intermittent fasting that reduces hunger and improves mood and sleep.

The researchers, affiliated with King’s College London, a consistently top-ranked university globally, recently presented their findings revealing what might be considered the optimal duration for time-restricted eating. The study involved over 37,000 participants who were asked to maintain their regular diet for one week and then adhere to a 10-hour eating window for the subsequent two weeks using a health app called ZOE. According to the researchers, participants experienced elevated mood and energy levels, along with reduced hunger. Moreover, the 10-hour eating window proved so manageable that almost all participants chose to continue with the plan for several additional weeks.

Sarah Berry, Ph.D., an associate professor at King’s College London and the chief scientist at ZOE, expressed enthusiasm about the study’s implications: “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. 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.” Dr. Berry highlighted the importance of consistency and maintainability, noting that those who practiced time-restricted eating inconsistently did not experience the same positive health effects.

“This study adds to the growing body of evidence showing the importance of how you eat. 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 show 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,” Dr. Berry emphasized.

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Recent studies in the U.S. support the findings of the U.K. study. A study published in the Journal of the American Medical Association (JAMA) affirmed the benefits of a limited eating window, showing that counting calories within a restricted timeframe was more effective than calorie counting alone. Another study in the journal Nutrients indicated that starting the eating window before 11 a.m. yielded greater health benefits and more weight loss than a later window. Together with the King’s College London study, these findings suggest that an overnight fast and a larger eating window can be as effective and beneficial as more restricted approaches. This implies that individuals can still incorporate breakfast, lunch, and dinner into their daily routine while experimenting with intermittent fasting without committing to more stringent forms of it.

Importantly, none of these studies advocated for cutting back on specific foods, although maintaining a healthy, balanced diet is always recommended and a healthcare provider should be contacted before undertaking any diet change. For those accustomed to snacking throughout the day, a restricted eating window may offer even greater benefits, according to the study results. And, don’t fret that you won’t be able to maintain it. While a 14-hour fast sounds like a long time, much of your fasting time will be spent sleeping. For instance, if breakfast is consumed at 9 a.m., completing the eating window by 7 p.m. allows for breakfast, lunch, and dinner. And you just might find, like the study participants, that this will be a painless way of eating that boosts your energy and leaves you not wanting that bedtime snack.