This approach can benefit individuals dealing with chronic insomnia and anxiety, too.
Intermittent fasting has become a go-to strategy for health and weight management for more and more people. Recent research suggests that avoiding eating for a minimum of 14 hours each night and restricting eating to a 10-hour window during the day (14:10) can enhance sleep, mood, and energy levels while reducing feelings of hunger.
This approach can benefit individuals dealing with chronic insomnia and anxiety, too. It can also be helpful for those facing issues such as fatigue and increased hunger resulting from dieting for weight loss.
The Different Forms of Fasting
There are various forms of intermittent fasting. In a 24-hour cycle, the most rigorous form is perhaps one-meal-a-day (23:1) fasting, while the more popular ones include 18:6 (essentially two meals a day, or eating only within a six-hour window) and 16:8 fasting. Intermittent fasting can also be structured on a weekly basis, such as the 5:2 (two days of light fasting each week whereby you eat less than 500 calories) and alternate-day fasting, whereby you eat less than 500 calories every other day.
Compared to these other intermittent fasting methods, the 14:10 fasting approach has a shorter fasting period and a longer eating window. It doesn’t significantly disrupt the usual three meals a day, making it relatively more flexible and easier to sustain. For example, if you start eating at 8 a.m., your last meal must be finished before 6 p.m., with no eating afterward.
What the Science Says
A research team from King’s College London conducted a study with 37,545 participants using the Zoe Health app. Results of the study were presented at the European Nutrition Conference on Nov. 14, 2023, in Belgrade, Serbia. In the first week of the study, participants were instructed to maintain their usual dietary habits, followed by two weeks during which they restricted their meals to a 10-hour window each day, referred to as the “eating window.” More than 36,231 participants chose to continue for additional weeks, with 27,371 considered “highly engaged.” Among this highly engaged group, 78 percent were female, with an average age of 60 and a body mass index (BMI) of 25.6 (normal range is between 18.5 and 24.9).
The study found that those who consistently ate within a fixed eating window had greater benefits than those with varying eating windows. Moreover, individuals who had the longest duration between their first and last bite each day before the intervention experienced greater improvements in their overall health.
Sarah Berry, associate professor at King’s College London and chief scientist at Zoe, said in a statement: “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, improved mood, energy levels and hunger.”
However, she also emphasized the importance of consistency.
“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,” she said.
Kate Bermingham from King’s College London and Zoe said that the study further demonstrates the importance of how we eat.
“The health impact of food is not just what you eat but the time at which you choose to consume your meals,” she said. “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.”
A study published in Nature Medicine in April 2023 involving more than 200 participants and spanning 18 months found intermittent fasting more effective in reducing the risk of Type 2 diabetes than a calorie-restricted diet. In this experiment, intermittent fasting involved selecting three nonconsecutive days each week as fasting days, during which participants consumed two meals between 8 a.m. and 12 p.m., totaling only 30 percent of their daily energy requirements.
They refrained from eating anything for the remaining 20 hours and were free to eat ad libitum on the other four days of the week. After six months, participants practicing intermittent fasting showed a significant reduction in postprandial blood sugar, indicating enhanced glucose metabolism. This improvement was more pronounced than that of the group following a calorie-restricted diet.
A small-scale clinical trial published in Cell Metabolism in 2020 focusing on patients with metabolic syndrome found that following a 14:10 intermittent fasting plan for 12 weeks not only aided in weight loss but also resulted in reductions in waist circumference, body fat percentage, visceral fat, and improvements in blood pressure, atherogenic lipids, glycated hemoglobin (a blood sugar indicator), and sleep quality.
Exploring the Health Benefits of Intermittent Fasting
A review study published in The New England Journal of Medicine (NEJM) in 2020 summarized three intermittent fasting methods: alternate-day fasting, 5:2 fasting, and one-meal-a-day fasting, highlighting their numerous health benefits. These include improved glucose regulation, enhanced stress resistance, and suppression of inflammation. Intermittent fasting has demonstrated potent alleviating effects on various chronic diseases in animal models, such as effects on obesity, diabetes, cardiovascular diseases, cancer, and neurodegenerative brain disorders such as Alzheimer’s and Parkinson’s diseases.
Mark Mattson, a Johns Hopkins School of Medicine neuroscientist and one of the authors of the study, said in a statement that after several hours without eating, the body depletes its sugar stores and begins to burn fat. The purpose of intermittent fasting is to prolong the body’s fat-burning period.
The Key to Success in Intermittent Fasting
Regardless of the chosen intermittent fasting method, achieving optimal results relies on long-term consistency, as indicated by multiple studies. The body may take two to four weeks to adapt to intermittent fasting, during which you might experience hunger or irritability. After overcoming this initial phase, sustaining the practice in the long run becomes more manageable.
Therefore, it’s advisable to start intermittent fasting with the easiest method, such as 14:10. After adapting for a certain period, you can then progress to more rigorous fasting methods such as 16:8 or 18:6.
It’s worth noting that regular eating outside the fasting window doesn’t imply unrestrained indulgence, even though intermittent fasting doesn’t impose specific dietary restrictions. A study published in the Journal of the American Heart Association (JAHA) in January 2023 found that over a six-year follow-up period, the time interval between participants’ first and last meal each day wasn’t directly correlated with changes in body weight. Instead, reducing the frequency of large meals could be associated with weight control.
Additionally, longer fasting periods aren’t necessarily better. Extended durations of fasting, such as 24, 36, or 48 hours, pose risks and may not yield additional benefits. This is because prolonged periods without food might prompt your body to store more fat in response to hunger.
Is Intermittent Fasting Safe?
Intermittent fasting may lead to unpleasant side effects, including hunger, fatigue, insomnia, nausea, headaches, and more, but these symptoms usually subside within a month.
Intermittent fasting is generally safe for most people but may not suit everyone. Pregnant or breastfeeding women, children and adolescents under 18 years old, those with Type 1 diabetes taking insulin, and individuals with a history of eating disorders should avoid intermittent fasting. It’s advisable to consult a doctor before attempting an intermittent fasting regimen.