Is eating dinner late at night bad? Understand if there are health risks

With a busy routine, work, studies, household chores and other obligations, it is common for many people to leave dinner late, close to bedtime. To give you an idea, a recent study showed that almost 60% of adults in the United States think it's normal to eat after 9 pm.

The research, published in October last year in the journal Clinical Nutrition, was conducted with more than 34,000 Americans over a 15-year period. The conclusion of the study showed that, despite the call for people to change their eating habits, there is still little change in late dining behavior. But does this bring any harm to your health?

According to Leonardo Parr, director of the Brazilian Society of Endocrinology and Metabology Regional São Paulo (SBEM-SP), eating late at night can alter several metabolic processes in the body. “Due to the complex interaction between the biological clock, glycemic metabolism and appetite regulation, the habit of eating late can cause a disruption in the body's circadian rhythms, affecting the secretion of endocrine hormones, such as insulin, ghrelin, leptin and melatonin” , explains.

This hormonal imbalance caused by a late dinner can increase the risk of developing obesity. “Insulin resistance induced by the habit of eating late can lead to excessive fat storage, especially in the abdominal region”, explains Leonardo. “In addition, the high production of ghrelin and the decrease in leptin (hormones related to appetite control) can lead to an increased feeling of hunger and less ability to control food intake, including the next day”, he adds.

One 2019 study underlies this relationship between late dinner and obesity. According to the researchers, those who ate dinner close to bedtime had an increased risk of being overweight or obese compared to those who ate dinner earlier. The study was carried out with 872 middle-aged or elderly North American adults.

Furthermore, a French study showed that those who eat meals earlier may have a lower risk of developing cardiovascular diseases, such as stroke and heart attack. Researchers analyzed data from 103,389 people and found that cardiovascular risk increases by 6% for every hour of delay in eating the first meal of the day.

Eating a late dinner is also associated with a higher risk of type 2 diabetes

Eating the last meal of the day late at night may also increase the risk of type 2 diabetes. A study published in 2023 in European Journal of Nutrition showed that those who ate regularly after 9pm had higher levels of HbA1c, a biomarker of diabetes risk. Furthermore, these people also had higher blood sugar levels after daytime meals compared to those who didn't eat dinner that late.

“Prolonged exposure to high blood glucose levels after a late meal can overload the beta cells of the pancreas, responsible for insulin production, leading to exhaustion and decreased function over time. This can result in chronic hyperglycemia and the development of insulin resistance, a precursor to type 2 diabetes,” says Leonardo.

Sleep quality is altered by late meals

It's not just your metabolic health that can be affected by eating a late dinner. Sleep quality is also related to when your last meal was eaten. This is because eating late can deregulate the secretion of melatonin, a sleep hormone, leading to difficulty sleeping and poor sleep quality.

“In addition, when someone lies down after a late meal, gravity can facilitate acid reflux into the esophagus, especially if there is a delay in gastric emptying”, explains the endocrinologist. “Not only does this cause discomfort, but it can also disrupt sleep, leading to frequent awakenings, difficulty falling asleep again, and reduced overall sleep quality.”

How to regulate dinner time and improve overall health?

In everyday life, it can be challenging to maintain a regular dinner and bedtime routine, but this is an important step towards maintaining health and worth trying. In the view of nutritionist Tatiane do Nascimento, who works for Segmedic, the best time to have the last meal of the day is around 7pm. “With this, we have an interval of two to three hours to start sleeping,” she says.

In addition to establishing a fixed time for dinner, it is interesting to take special care with your nighttime diet, always including vegetables, salads, fruits, proteins and fiber on the menu. Carbohydrates, contrary to what many people think, can and should be present on the plate.

“The story that carbohydrates should be avoided at dinner is a myth. There are no problems with them being consumed at night, but the ideal is to focus on healthy foods and avoid excesses”, warns Tatiane. Therefore, the guideline is to consume complex carbohydrates, such as sweet potatoes, brown rice, oats, beans, peas, lentils, among others.