Eating late at night may seem like a quick and convenient solution for shift workers, students under academic pressure or sports fans who sacrifice sleep for important games. However, this habit, which seems seemingly harmless, has serious health consequences. The key to understanding the damage is an internal mechanism that meticulously manages our bodies, our biological clock.
The biological clock: Our inner health guardian
The biological clock is a complex system that dictates the rhythm at which the body's systems operate throughout the day. At the center of this mechanism is the suprachiasmatic nucleus (SCN) in the brain, which receives signals about changes in light and darkness and coordinates between smaller clocks located in various organs such as the heart, liver and intestines. This mechanism allows the body to maintain regular rhythms that ensure functional efficiency.
During the day, the body prepares for intense activity – releasing hormones such as cortisol that increase alertness and stimulate metabolism. In contrast, at night, the digestive system works slowly, and the sleep system prepares for restoration processes. Disrupting this balance, for example by eating at night, disrupts the internal rhythm, leads to a number of health problems and paves the way for chronic diseases.
The biological clock is affected not only by the hours of light and darkness, but also by the timing of meals. Researchers have discovered that meal times can change the activity of clocks in organs such as the liver and intestines, even without a change in lighting conditions. For example, in people who eat their main meal at night, the liver's clocks begin to operate at a rate that is not coordinated with the rest of the body's systems. This mismatch disrupts metabolism and increases the risk of chronic diseases such as diabetes, obesity and heart disease.
Continuous disruption of the biological clock, as happens to people who work night shifts or consume food at irregular times, can cause a decrease in immune system function, with studies showing that people with a disrupted biological clock tend to develop more infections and inflammations, and disruption of circadian rhythms leads to changes in blood pressure and cholesterol levels, which leads to an increased risk of cardiovascular disease.
How does nighttime eating affect the body?
Disrupting the biological clock by eating late affects hormones that regulate hunger and satiety. A study conducted at Harvard University showed that eating at night causes a decrease in levels of the satiety hormone leptin and an increase in levels of the hunger hormone ghrelin. As a result, people who eat at night tend to experience increased hunger throughout the day and therefore gain weight.
Eating late has been found to lead to a decrease in the rate of calorie burning. This means that the calories consumed are stored in the body as fat, instead of being converted into available energy, thus increasing the risk of obesity. These effects are noticeable even in healthy people, but in those who suffer from obesity or diabetes, the consequences are even more serious.
In addition to the metabolic effect, nighttime eating also impairs sleep. Studies indicate that eating close to bedtime increases awakenings during the night and disrupts sleep structure. Furthermore, heavy meals at these times may encourage acid reflux and lead to digestive discomfort, a condition that exacerbates sleep disturbances and the cycle of fatigue that follows the next day.
When we are tired or stressed, we tend to look for instant solutions in the form of high-sugar foods or basic carbohydrates, which provide a feeling of "available energy." But eating this late creates a cycle of guilt, obesity and continued disruption of the biological clock. The result is a repetitive pattern that is difficult to break.
It is important to note that nighttime eating not only affects the body's energy balance, but also blood sugar levels. A study published in 2020 found that people who ate dinner at 10:00 PM instead of 6:00 PM experienced an approximately 20% increase in blood sugar levels and a 10% decrease in fat burning ability. These findings highlight the direct link between late eating and the risk of developing type 2 diabetes, even in people without a history of the disease.
Several studies were conducted among diabetic patients at the Wolfson Medical Center which proved that the biological clock is indeed affected by the timing of the meal, with a rich and late dinner causing weight gain and impaired glycemic balance. These studies scientifically proved what Maimonides, the greatest physician of the Jewish people, said about 800 years ago: "Eat breakfast like a king, lunch like a prince, and dinner like a pauper. "
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To maintain a healthy balance, it is recommended to eat main meals during the day, not to skip breakfast, when the body is prepared to utilize energy optimally. It is important to avoid eating at least three hours before bedtime, in order to allow the body to focus on night-time repair and restoration processes. And if you must eat at night, prefer light foods such as yogurt, nuts, or bananas, which reduce the load on our metabolism.
For shift workers or people with irregular schedules, maintaining regular meal times can help balance the circadian clock, even if eating occurs at night. In short, our eating is not just a matter of what and how much, but also when. A thorough understanding of the circadian clock and its role allows us to improve our quality of life, prevent obesity and diabetes, and maintain an internal balance that contributes to long-term health.