Intermittent Fasting Doesn't Need To Be Extreme To Boost Mood And Lower Hunger

Eating all your meals within a specific timeframe really isn’t that wild of an idea.

A man eating breakfast.
Ariela Basson/Fatherly; Getty Images

Diets suck. They’re restrictive and teach kids harmful messages about food and bodies, and you tend to gain the weight back anyway. But intermittent fasting isn’t a diet per se. You can eat all the food you normally do — just within a limited time frame per day. And a new study finds that the timeframe doesn’t need to be super small to make you feel better and less hungry.

The UK-based study, which has not yet been peer-reviewed and was presented at the European Nutrition Conference in Belgrade, Serbia in November, had 37,545 users of the ZOE Health app eat like normal for a week, and then only within a 10-hour window each day for two weeks. The participants also answered questionnaires, about their hunger and energy levels among other topics.

Researchers found that eating within a 10-hour period improved mood and energy levels and reduced hunger.

“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,” Dr. Sarah Berry, a reader at King’s College London and chief scientist at ZOE, said in a press release. “What's really exciting is that the findings show that you don’t have to be very restrictive to see positive results. A 10-hour eating window, which was manageable for most people, improved mood, energy levels, and hunger.”

More than 96% of participants chose to continue in the study for additional weeks, and more than 70% were “highly engaged,” meaning they regularly completed the questionnaires. This indicates that they found the 14-hour fast fairly easy to do.

Everyday Health reported that the participants also noticed improved sleep with intermittent fasting. And more than half of highly engaged users lost an average of nearly 2.5 pounds over two to 16 weeks of fasting for 14 hours each day.

Some proponents of intermittent fasting recommend only eating within a six-hour window each day. But this new study shows that such a long fasting period isn’t necessary to see benefits.

And a 10-hour window really isn’t that restrictive. If you eat breakfast at 9 a.m., you just need to have dinner by 7 p.m. — and no snacking later in the night. If you mess up every now and then, it’s no big deal. The researchers found that participants experienced positive results even when they didn’t stick to the 10-hour window every day, though those who were consistent did have better results.

Additionally, the benefits were more extreme for people who had eaten throughout more hours of the day before starting the study.

“I was surprised that even reducing your eating window by, on average, two hours, there is still a really big improvement on how people felt,” Berry told Everyday Health.

It’s worth noting that there was no control arm in the experiment — in other words, there wasn’t a group that didn’t do intermittent fasting. So it’s hard to tell how much the placebo effect could have made participants feel more energetic, have better mood, and be less hungry.

However, the study is still a big leap forward in our understanding of intermittent fasting because it’s one of the only studies to look at a large group of people trying it in their daily lives, rather than a small group trying it in a controlled, laboratory-like environment.

“The health impact of food is not just what you eat but the time at which you choose to consume your meals,” Dr. Kate Bermingham, a postdoctoral researcher at King’s College London and a researcher at ZOE, said in the press release. “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 10-hour window.”

Intermittent fasting has more benefits than just those found in the study. Previous research has found that it can also improve blood pressure, cholesterol, and asthma symptoms. It also may be able to improve thinking and memory, prevent obesity, and reduce insulin resistance.

So cut out the midnight snacks and get the family ready for earlier dinners. Because intermittent fasting may be one of the easiest ways to feel better and get healthier — all without changing what you eat.