When you eat dinner may matter as much as what you eat. Here’s what research says about the downsides of dining late.
Late Eating Can Disrupt Sleep
Late dinners may interfere with sleep in a couple of ways: digestive discomfort and elevated blood sugar.
A late, heavy meal could keep you tossing and turning with heartburn or indigestion. Spicy or greasy foods like pizza or nachos are especially likely to cause issues, since they tend to delay digestion and sit in your stomach longer.
“Additionally, lying down flat too soon after dinner can increase symptoms of gastric reflux, which may be uncomfortable and prevent you from falling asleep easily,” adds Groves Azzaro. (Reflux occurs when stomach acid flows back up the esophagus.)
A late dinner can also mess with your sleep by elevating your blood sugar. “Eating dinner late means that your body is still working on digesting and absorbing the food you ate, which means that your blood sugar is still high by the time you go to bed,” Groves Azzaro says.
Some research has correlated disrupted sleep with high blood sugar, and the two may go hand in hand. High blood glucose levels can impact sleep by increasing nighttime trips to the bathroom. Eating close to bedtime may also raise hormones that disturb sleep. “Late dinner has been shown to increase nighttime cortisol levels, which may result in sleep that is interrupted and less restorative,” Groves Azzaro says.
Eating Late May Cause Weight Gain
Late dinners can sabotage weight loss and management efforts by disrupting your metabolism. A small study found that consuming calories later in the day was linked to obesity and metabolic syndrome.
Late dinners disrupt blood sugar and increase levels of insulin (the hormone that regulates blood sugar), throwing off hunger cues. “I often see that eating dinner late at night leads to decreased hunger in the morning, which can lead to undereating throughout the day and then overeating at night,” says Groves Azzaro. This creates a vicious cycle, because the body processes glucose (sugar) more efficiently in the morning than in the evening. As a result, late-night eating leads to more glucose being stored as fat.
Late eating also interferes with hunger hormones. “Eating dinner late at night can increase ghrelin (the hunger hormone) and decrease leptin (the fullness hormone), resulting in decreased calorie expenditure and increased fat storage,” Groves Azzaro says.
Late Dinners May Increase Disease Risk
A late-night dinner habit might increase your risk of chronic diseases like type 2 diabetes and cardiovascular disease by disrupting your circadian rhythm.
“Eating closer to sleep onset can increase glucose concentrations overnight and the following morning,” says Alyssa Tindall, PhD, RDN, a registered dietitian-nutritionist and an assistant professor of health sciences at Ursinus College in Collegeville, Pennsylvania. This impairs your body’s ability to process and use glucose over time, raising diabetes risk. A small study found that people with overweight, obesity, or prediabetes who ate later dinners had poorer glucose control.
The same study linked consuming over 45 percent of daily calories after 5 p.m. to higher cardiovascular disease risk. Additional research supports this connection: one study found that eating dinner after 9 p.m. (compared with before 8 p.m.) was associated with a higher risk of stroke, especially among women.
Researchers speculate this may be because eating at consistent times that align with daylight hours helps support optimal blood pressure and metabolism. (Your metabolism helps regulate your heart rate.)