In Spain we love to have dinner at ten at night. To our biological clock and our heart, not so much

Eating dinner at 9 or 10 at night is something that is quite normal for Spaniards, but seen by foreigners, it is something that shocks them quite a bit as it is so different from the customs of other countries. And although our normality is to eat at three in the afternoon and dinner at ten at nightthe reality is that our biological clock is not designed to digest large amounts of food when the sun has already set.

Time matters. Although in recent years we have been obsessed with looking at the ingredients of what we eat or the amount of calories it contains, the reality is that science gives more and more importance to consumption. This is where chrononutrition comes from, an emerging discipline that studies the relationship between circadian cycles and our diet, and that little by little is seeing that eating late dinners has a direct impact on our metabolic health. our quality of sleep and our risk cardiovascular.

The biological clock. Our body works like an orchestra perfectly synchronized by circadian rhythmsand leaving them has serious consequences. We see it, for example, with the famous jet lagthe time change or even when we go to bed at a time that is not ours. The result is that the body has to recover again and has important effects, such as great fatigue.

In the case of eating at odd hours, especially at dinner, we are desynchronizing the peripheral clocks that the cells of organs as important as the pancreas or liver have. And this results in a drastic worsening of glucose tolerance and also insulin secretion.

Its effect. And it has consequences, since when we eat dinner close to our biological bedtime, that is, when the sun is setting, the body reduces the consumption of nocturnal fats and there is also a large release of cortisol, which is the stress hormone, and the release of melatonin, which is essential for falling asleep, is delayed.

This is something that became clear in a 2025 meta-analysis, where it is detailed that eating after nine at night worsens the rhythms of neurotransmitters such as serotonin and dopamine, which not only has a metabolic impact, but also an emotional one, increasing the risk of depression.

The Spanish case. If we focus precisely on our country, we have as a reference the study led by the ISGlobal institute that analyzed to 100,000 participants of the NutriNet-Santé cohort. Here it was concluded that dining after 9 pm is associated with a greater cardiovascular risk, especially impacting the risk of cerebrovascular disease in women.

In the case of weight. If you want to lose weight, dinner time also has a lot of influence, as noted in a study by researcher Marta Garaulet that showed that people who eat later at midday lose less weight than those who eat early, even when they consume the same calories and expend the same amount of energy and sleep the same amount.

Added to this are studies in Catalan adults that associate the delay of the first meal of the day with a higher BMIwhile extending overnight fasting is related to a lower BMI.

Beyond the scale. Although we may keep in mind the impact on digestion, the reality is that studies suggest that having late meal times is related to poorer quality of sleep. This was seen in the United States, where science pointed out that in middle-aged women it has been proven that bringing dinner time closer to bedtime prolongs the time it takes to fall asleep, therefore shortening the effective duration of rest.

And as we already know, having poor quality sleep generates many other problems, such as a worse cardiometabolic profile, which generates a true vicious circle.

Its nuances. Logically, having a late dinner alone does not explain the state of health of the Spanish population, since the context has a lot of influence. This is where the traditional Spanish Mediterranean diet comes in, which makes dinners later meals, but also much lighter, leaving the main energy weight for the midday meal. That is why you should keep in mind that a late, copious and ultra-processed dinner followed by a trip straight to bed is not the same as a light dinner accompanied by some physical activity before going to sleep.

Even so, science suggests that, if the objective is to reduce metabolic risk, improve carbohydrate metabolism and lose weight, the winning strategy involves advance dinner time and maintain a longer overnight fasting window.

Images | Eiliev Aceron Shane

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