To lose weight, to rest well… Science knows what time you should eat

To lose weight, to rest well… Science knows what time you should eat

There is scientific evidence that chrononutrition works; That is to say, depending on the time of day in which the food is ingested, the body obtains or rather generates one response or another. A group of researchers from the University of the Basque Country (UPV/EHU) began to compile articles published in scientific journals that analyzed how aspects such as the weight gain or loss of an overweight or obese person were affected depending on the time of day. the one where they had their main meals. And they were surprised by some of the results.

For example, imagine a group of people who have been on significant calorie restriction for 20 weeks as a treatment to lose weight. Well, “in those who ate after 3 p.m. – that is, after three in the afternoon – the weight loss was less than in those who ate before,” explains Alfredo Fernández, member of the Nutrition and Nutrition Research Group. Obesity of the Faculty of Pharmacy, the CIBER of obesity and nutrition (CIBERobn) of the Carlos III Health Institute, and the BioAraba Biosanitary Research Institute. “Therefore, not only the composition of the diet and the calorie intake are important, along with the increase in physical activity, but also the time at which these foods are eaten.”

Based on this, how and what could we use chrononutrition for? This concept, developed in the 80s of the last century, consists, Fernández explains, of a kind of nutritional regime that follows our biological clock, “a whole machinery controlled by the hypothalamus and by metabolically active organs such as the pancreas, the stomach or the muscles. This biological clock regulates daily rhythms such as the time spent awake or asleep, the period of fasting or eating, and even small changes in body temperature throughout the day.

The expert adds that the daily light/dark cycle is one of the main regulators of this biological clock, as are the periods of food intake and fasting. «Then an alteration of meal times (increasingly later), as well as irregular eating can alter this control of our biological clock. And a lack of harmony between the times of our meals and the biological clock has been related to an increase in the amount of body fat, or what is the same as a higher body weight, in addition to type 2 diabetes and other factors. cardiometabolic risk such as plasma triglyceride concentration.

The invention of electricity

Iva Marques is a dietitian-nutritionist from the Spanish Academy of Nutrition and Dietetics, a doctor in Pharmacy and a professor of Nutrition and Bromatology at the University of Zaragoza. She points out that, based on respect for our body’s biological clock, “we begin to be prepared to receive food from 6 in the morning, which is when the secretion of melatonin begins to decrease and the hormone cortisol increases. “Then we should eat following our circadian rhythm, placing caloric intake between 6 in the morning and 9 at night.”

What would then be the smartest formula to eat based on chrononutrition? The expert responds that it would have a lot to do with the hours of sleep we need, “something that right now is a big problem in our society, the lack of sleep and rest. “Since humans invented electricity, we have gone against our biology, which is adapted to the natural cycle of the sun and that is how we have functioned for thousands of years.”

A damaged bicycle

Marques proposes promoting rest, physical activity, healthy eating, sleep and stress management. He adds that based on everything said, the smartest thing is to start feeding at 6 or 7, with the rise in cortisol. And up to a maximum of two hours before going to sleep, in 2, 3 or 4 intakes, depending on lifestyle and physical activity. «If we go to bed at midnight, the maximum time to eat something would be 10pm, although in reality we should go to bed at that time to get the 7 or 8 hours of sleep we need. However, scientific studies estimate that dinners should last until 9 p.m. at most, do something quiet until 11 p.m., and go to bed.”

–And what happens if we have dinner or something to eat at dawn??

– Iva Marques: Absolutely nothing, because we are biologically very efficient, but what we do is what is called ‘chronodisruption’, that is, at 9 p.m. the secretion of melatonin is activated and causes all the body’s biological clocks to stop. put them in rest and repair mode, especially after 11 p.m. Eating food too late can lead to lower absorption and metabolization rates. A late dinner (11-12 at night) results in a late increase in blood glucose: the central clock, which has been focused since 9 pm on resting and repairing, becomes desynchronized with the clock of the stomach and pancreas, which secrete insulin. «It’s like a bicycle with one wheel moving forward and the other backward. Not going well.

Late dinners, social jet lag (going to bed systematically late), shift work and exposure to blue light from screens work as chronodisruptors

The researcher Alfredo Fernández summarizes these theses in that the majority of calories and carbohydrates should be ingested at lunchtime and early in the afternoon, avoiding dinner at night: «In addition to the quantity and content of macronutrients and micronutrients, “The timing of food intake during daylight periods, versus that which occurs during the night, is essential for the well-being of an organism and could represent an interesting strategy to maintain metabolic health or promote weight loss.” .

– With Spanish schedules and dinners approaching midnight, chrononutrition is difficult to follow. Perhaps the most appropriate thing would be to follow the Mediterranean diet with European customs?

– Fernandez: The Mediterranean diet model is associated with a healthy food profile, but it also takes into account other aspects such as socialization, or dedicating a reasonable amount of time to meals. This sometimes causes, for example, dinner to be delayed until around 9:00 p.m., which is not the most appropriate for controlling our biological clock. However, other European countries with an earlier schedule, such as Norway or Finland, do not present better data regarding the incidence of cardiovascular diseases. What we could improve is the mistake that we are going to bed shortly after having dinner, since we should have a light dinner and leave at least an hour or an hour and a half before going to rest.

The chocolate test


of chocolate (500 calories) ingested by two groups of women for two weeks, some in the morning and others at night, showed in the former a spontaneous reduction in food intake that was not seen in the latter.

– Could it be summarized in eating during the hours of the day, going from more quantity to less? That thing about having breakfast like a king, eating like a prince and having dinner like a beggar…

– Indeed, the greatest amount of food should be concentrated in the hours in which we are most active, that is, during daylight hours, and eat a smaller amount of food from mid-afternoon. This can be a problem in shift work.

– Is there a difference between eating a couple of ounces of chocolate at 10 in the morning or doing it at 10 at night?

– Well, with two ounces of chocolate there may not be much, but different effects have been described with the consumption of a high amount (100 grams, about 500 kilocalories) of chocolate in the morning or at night for two weeks. A study with women showed that those who took chocolate in the morning showed a reduction in spontaneous food intake that was not observed in women who took it in the afternoon/evening, while the latter showed a lower appetite for other sweet foods and better sleep quality.

– And does the order in which we eat food also matter?

– More studies are needed. But there is a new line of research to analyze the impact of food on blood glucose control, interesting for people with prediabetes or diabetes. It has been observed that consuming foods rich in fiber (vegetables and fruits) first, followed by protein foods (meats and fish) and leaving carbohydrates (cereals) for last could reduce sugar spikes after meals and reduce blood glucose concentration. If we eat a plate of vegetables with a little rice and salmon, we should eat the vegetables first and leave the rice for last, because this would reduce sudden increases in blood sugar.

Early and more protein dinner

Alfredo Fernández advises not to skip breakfast and to make it important, 25% of the total intake: “Cereals, a good cup of coffee with milk, yogurt and a piece of fruit.” A small mid-morning lunch, close to 10-15% of daily calories, “would help concentrate intake when we are most active.” We should dedicate an hour to food “before 3:00 p.m., and make it the most important intake of the day, 30% of the kcal. For example, vegetables with rice and fish with some bread and fruit. For dinner, before 9 p.m., more proteins (meat or fish) and few carbohydrates. Make it 20% of the kcal. “The higher plasma concentration of glucose that carbohydrates contain contributes to weight gain due to the lower metabolic rate, that is, less energy expenditure during sleep.”

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