Eating at night can affect more than just your waistline.
You’ve probably heard that you’re not supposed to eat late at night because it can make you gain weight. There’s even a health movement around intermittent fasting, where people consciously try to abstain from eating for 12 to 15 hours a night (say, from 7 PM to 7 AM) because it might be better for their metabolism. But, hey, 9:30 dinner reservations happen, as do 11 PM cravings for Rocky Road or third helpings of chicken parm.
So we asked Sharon Richter, RD, a nutritionist in New York City, whether those late-night munchies really do pack on the pounds.
“When it comes to late night eating and weight gain, it depends on what you eat, how often, and how much,” says Richter. Eating foods that are high in fat, sugar, and calories can cause weight gain no matter what time of day it is.
Even so, researchers are still gnawing at the topic, because some research suggests all mealtimes may not be created equally.
The Early, Yet Interesting, Research
Here’s where it gets tricky: Some studies suggest that late-night eating may have a negative impact on weight and metabolism, while other research seems to explain that noshing at night may actually be beneficial.
One small Penn Medicine study compared the effects of daytime eating (from 8 AM to 7 PM) and nighttime eating (from 12 PM to 11PM) in nine participants. Researchers found that those who ate later showed an increase in weight, as well as a rise in cholesterol, insulin, fasting glucose, and triglyceride levels.
Another study of about 400 hundred participants showed that night eating syndrome—which is when a person eats most of their meals after sundown—is associated with binge eating and higher body mass index (BMI).
Conversely, a 2015 review of studies concluded that eating a small, nutritious meal at nighttime may actually help you build muscle and benefit cardiometabolic health (your risk for heart disease and diabetes).
The Real Talk on Late-Night Eating
As interesting (and as mixed) as the research is, it’s time to tell it like it is: When clock strikes eat o’clock at the end of the day, it’s unlikely that you’re going to reach for the carrots and hummus or steamed broccoli—especially if you’re tired or unwinding from a stressful day.
“Part of the reason late night eating is linked with weight gain is because we tend to consume high-fat, high-sugar, high-calorie foods, like pizza or ice cream,” says Richter.
Junky munchies not only contribute to weight gain whether they’re eaten morning, noon or night, but they can also interfere with your ability to get a good night’s rest, which can trigger a weight-sabotaging cycle. That’s because certain eats can disrupt your sleep. Sweets can cause sugar spikes; fried or heavy foods may cause indigestion. If you’re tossing and turning all night from digestive troubles, it can mess with your hunger hormones the next day, which may cause you to eat more—all day. What’s more, appetite levels and ghrelin (your “I’m hungry” hormone), tend to naturally increase at night (which researchers believe is the body’s way of preparing for our overnight fast, a.k.a. sleep), which can jump start that cycle all over again.
“If you’re hungry after 8 PM, it’s OK to listen to your body and eat, as long as it’s nutritious, and a moderate portion,” says Richter. Even better, eat something that may help you sleep. Choose a light snack with complex carbohydrates, fiber, and protein, like whole grain bread with peanut butter, or oatmeal with milk. “High-fiber foods break down slowly to help avoid sugar spikes, and carbohydrates can help you feel drowsy,” says Richter.
The Health Impact of Nighttime Eating: Old and New Perspectives. Tallahassee, FL: Institute of Sports Sciences & Medicine, Department of Nutrition, Food and Exercise Sciences, Florida State University, 2015. (Accessed on February 1, 2018 at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4425165)
Timing Meals Later at Night Can Cause Weight Gain and Impair Fat Metabolism. Philadelphia, PA: Penn Medicine, 2017. (Accessed on February 1, 2018 at https://www.pennmedicine.org/news/news-releases/2017/june/timing-meals-later-at-night-can-cause-weight-gain-and-impair-fat-metabolism)
Short Sleep Duration Is Associated with Reduced Leptin, Elevated Ghrelin, and Increased Body Mass Index. Palo Alto, CA: Stanford University, 2004. (Accessed on February 1, 2018 at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC535701)
The Internal Circadian Clock Increases Hunger and Appetite in the Evening Independent of Food Intake and Other Behaviors. Boston, MA: Medical Chronobiology Program, Division of Sleep Medicine, Brigham and Women’s Hospital, 2013. (Accessed on February 1, 2018 at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3655529)
Ghrelin fluctuation, what determines its production? Acta Biochimica et Biophysica Sinica, 2009. (Accessed on February 1, 2018 at https://academic.oup.com/abbs/article/41/3/188/655)
Night eating syndrome and nocturnal snacking: association with obesity, binge eating and psychological distress. Melbourne, Victoria, Australia: Centre for Obesity Research and Education,The Alfred Hospital, Monash University, 2007. (Accessed on February 1, 2018 at https://www.ncbi.nlm.nih.gov/pubmed/17579633)