Does nighttime eating make you gain weight?
A well-controlled study of 32 young women, published by the International Journal of Obesity, found that eating late is associated with a reduction in calories burned and reduced glucose tolerance.
You might have heard the adage, “Eat breakfast like a king, lunch like a prince and dinner like a pauper.”
But the truth is that most of us snack in the evening, sometimes even after a large dinner. According to the International Food Information Council’s 2021 Food and Health Survey, about 65% of those surveyed said they eat at least one snack in the evening, and nearly 50% said they consume at least one snack between 9 p.m. and 11 pm.
The question often asked is: Can eating at night make it harder to lose weight or even make you gain weight?
A well-controlled study of 32 young women, published by the International Journal of Obesity, found that eating late is associated with a reduction in calories burned and reduced glucose tolerance, among other detrimental effects. Whether this would be true in a wider age group or in men in addition to women isn’t known.
Another study, out of Japan, found that, among 11 young women, nighttime snacking not only reduced the burning of fat, but it also increased levels of total and LDL cholesterol in the blood, suggesting that nighttime eating changes fat metabolism and might increase the risk of weight gain and obesity.
According to Colleen Rauchut Tewksbury national spokesperson for the Academy of Nutrition and Dietetics, very small, controlled studies have shown that eating earlier is better for weight management than eating later, which might slow weight loss.
“My take is that there may be something here,” Tewksbury says. “Early data suggest that timing of eating could be an important factor in weight management. But the evidence isn’t to the point that we would issue a blanket recommendation that all late eating is detrimental to health.”
There are a few reasons why late-night snacking could be a problem.
Late-night snacking often is done in sync with watching streaming or television or even reading. Your focus is likely on the movie you’re watching or the book you’re reading, not the calories you’re consuming.
Reputable weight-loss programs include instruction on how to be mindful of what you’re putting in your mouth and not combine eating with any other activity, like watching TV or reading.
The results of a study of more than 800 men and women, each keeping food diaries for one week, showed that foods eaten late at night lack the satiety of foods eaten at other times of day, which results in an increase in food intake, a greater calorie intake for the day and ultimately weight gain.
Foods consumed late at night seldom include steamed broccoli or kale salads. Chips, cookies, cakes, trail mix and pretzels are among the more common fare for late-night snacking.
Calories from fat and sugar from these foods can quickly add up. The higher the fat and sugar, and sometimes sodium content, the more likely you are to crave more.
“Eating late can alter your circadian rhythm,” Tewksbury says.
As a result, it might affect your ability to sleep. Inadequate sleep has itself been associated with weight gain.
Some research suggests that late-night snacking can shift hormones, such as ghrelin, growth hormone and others and shift the body toward weight gain. Eating during the day, rather than at night, has been found to promote weight loss and improve insulin levels.
While nighttime snacking might cause a shift in hormones that affect appetite and alter your body’s circadian rhythm, eating before bedtime also increases the risk of experiencing acid reflux, when stomach acid or bile flows into the food pipe and irritates the lining.
Some experts have suggested it’s best to stop eating around 7 p.m. or 7:30 p.m.
But Tewsksbury says, “If someone sets a goal to reduce late eating, the best cutoff time is the one they can stick with.
“What we do not fully understand right now,” she says, “is how the body reacts to calories at different times and for different people. Recommendations for or against nighttime eating will change as science evolves and we have a better understanding.”
She suggests that her clients keep a detailed food journal to see if nighttime snacking is an issue and adjust their eating patterns by shifting snacking to earlier in the day.
Environmental Nutrition is a newsletter written by experts on health and nutrition.