For years, the concept has swirled around nutrition circles that it’s best to take a pass on late-night eating if you want to avoid weight gain. Now, there’s a new study that shows how much of an impact eating late can have on your body.
The study, which was published in the journal Cell Metabolism, was small—it only included 16 people who had overweight or obesity. But it was well-controlled, with researchers dictating the types of meals participants ate, how much physical activity they did, how much sleep they got, and even factors like room temperature and light exposure.
For the study, each participant was given a strict sleep and wake schedule for three weeks and were provided with prepared meals at set times. The participants were randomly assigned into one of two groups: A group that ate their meals at 8 am, 12 pm, and 4 pm, and a group the same meals four hours later—at 12 pm, 4 pm, and 8 pm
The researchers measured hunger levels and appetite 18 times over six days, along with the participants’ body fat, temperature, and how much energy they used.
The participants took a break for a few weeks and then switched groups. Meaning, those who ate later then ate earlier and vice-versa.
The researchers found that people were twice as likely to be hungry when they ate four hours later. They also craved more foods with salt, starch, and meat, than the earlier eating group.
“We found that eating four hours later makes a significant difference for our hunger levels, the way we burn calories after we eat, and the way we store fat,” study co-author Nina Vujovic, Ph.D., a researcher in the Brigham and Women’s Hospital’s Division of Sleep and Circadian Disorders, says in a press release.
If you tend to eat late, it’s understandable to have questions. Nutritionist break it down.
Why might eating late make you feel hungrier?
The researchers actually answered this question in the study. Blood tests showed that levels of ghrelin, a hormone that causes your appetite to rise, went up in the late-eating group while leptin, a hormone that signals when you feel full, were lower in this group compared to the early eaters. There was a significant difference: The ratio of ghrelin to leptin increased by 34% in the group that ate later.
Basically, eating late can cause you feel hungrier than normal without feeling as full as you would if you ate earlier.
Keri Gans, RD, author of The Small Change Diet, says she’s “not surprised” by the findings. “Sometimes it seems the longer you wait to eat, the longer it takes for your body to catch up with your hunger,” she says. “It can almost be thought of as the domino effect—once you finally take the one bite, you can’t stop.”
This can be tricky given that “many higher-calorie foods are more available to us later in the day, like restaurant food or fast food for a takeout dinner, snacks, and desserts at home, or even a larger portioned home-cooked meal, ” says Julie Palmer, RD, a dietitian at The Ohio State University Wexner Medical Center. These foods are easy to overeat, she says. “Plus, as our bodies and minds wind down from a long day at work, we are naturally looking for comfort, which can come in the form of food,” she adds.
Worth noting: Another study that was also just published in Cell Metabolism also found that eating more earlier in the day (and less at night) can leave you feeling more satisfied.
“If you’re eating earlier in the day, you may be more satisfied with food and eat less later in the evening,” says Scott Keatley, RD, co-owner of Keatley Medical Nutrition Therapy, “But if you have most of your calories later in the day, you may feel so unsatisfied by your previous foods that you overeat.”
Nutritionists say mindfulness is important.
Sometimes you’ll need to eat late—maybe it’s all that your work schedule allows or you just aren’t hungry earlier in the day. But Gans says that being prepared with healthy meals can help. “Planning ahead keeps you more on track and less likely to make poor choices at the last minute,” she says.
Keatley also recommends that you “try not to make the time between meals or snacks be a marathon.” That, he says, can leave you feeling hungrier when you eat and more likely to overeat.
“When you snack, have a source of protein, fat, and fiber in one sitting,” Keatley says. “This will help to make you feel satisfied.” Adding fruits and vegetables to your snacks and meals can also help fill you up and leave you feeling satisfied longer, he says.
If you can, Palmer recommends that you “make sure you are fueling your body during your most active hours.” If you can’t have time for a full meal, she suggests having balanced “mini meals” during your day, aiming to eat every three to four hours.
Keatley stresses that it’s “OK” if you need to eat late. Just be mindful of what you’re eating and, if you can, try to have it a little earlier so you feel more satisfied.
Korin Miller is a freelance writer specializing in general wellness, sexual health and relationships, and lifestyle trends, with work appearing in Men’s Health, Women’s Health, Self, Glamor, and more. She has a master’s degree from American University, lives by the beach, and hopes to own a teacup pig and taco truck one day.