L’obesity it affects approximately 42% of the adult population of the United States and contributes to the onset of chronic diseases, including diabetes, cancer, and other conditions. While popular healthy diet mantras advise against midnight snacking, few studies have comprehensively investigated the simultaneous effects of late dining on the three major players in regulating body weight and thus obesity risk: intake regulation. caloric, number of calories burned and molecular changes in adipose tissue.
A new study by researchers at Brigham and Women’s Hospital, a founding member of General Brigham’s health system, found that when we eat it significantly affects our energy expenditure, appetite, and the molecular pathways in fat tissue.
The results of the Research have been published in the scientific journal Cell Metabolism.
Eating late: that’s why it’s not a good habit
“We wanted to test mechanisms that could explain why eating late increases the risk of obesity,” explained senior author Frank AJL Scheer, Ph.D., Director of the Medical Chronobiology Program in Brigham’s Sleep and Circadian Disorders Division. “Previous research from us and others has shown that eating late is associated with an increased risk of obesity, increased body fat and decreased weight loss success. We wanted to understand why ”.
“In this study, we asked ourselves, ‘Does the time we eat matter when everything else is kept consistent?'” Said lead author Nina Vujović, Ph.D., researcher in the medical chronobiology program in Brigham’s Sleep division. and Circadian disorders. “And we found that eating four hours later makes a significant difference to our hunger levels, how we burn calories after eating and how we store fat.”
Vujović, Scheer and their team studied 16 patients with a body mass index (BMI) in the overweight or obese range. Each participant completed two laboratory protocols: one with a strictly scheduled advance meal schedule and the other with the exact same meals, each scheduled approximately four hours later in the day.
In the last two to three weeks before starting each of the protocols in the lab, participants maintained fixed sleep and wake times, and in the last three days before entering the lab they followed strictly identical diets and meal times at home. In the lab, participants regularly documented their hunger and appetite, provided frequent small blood samples throughout the day, and had their body temperature and energy expenditure measured.
To measure how late eating affected the molecular pathways involved in adipogenesis, or how the body stores fat, the researchers collected adipose tissue biopsies from a subset of participants during laboratory tests in early and late feeding protocols. to allow comparison of gene expression patterns / levels between these two food conditions.
The results revealed that eating late had profound effects on hunger and the appetite-regulating hormones leptin and ghrelin, which affect our urge to eat. In particular, levels of the hormone leptin, which signals satiety, decreased over 24 hours in the late feeding condition compared to the early feeding condition.
When participants started eating late, they also burned calories at a slower rate and showed fat tissue gene expression toward increased adipogenesis and decreased lipolysis, which promote fat growth. In particular, these findings convey the converging physiological and molecular mechanisms underlying the correlation between eating late and increasing the risk of obesity.
Vujović explained that these findings are not only consistent with a large body of research suggesting that eating late may increase the likelihood of developing obesity, but shed new light on how this could occur. Using a randomized crossover study and closely monitoring behavioral and environmental factors such as physical activity, posture, sleep and light exposure, the researchers were able to detect changes in the different control systems involved in energy balance. , an indicator of how our bodies use the food we consume.
In future studies, Scheer’s team aims to recruit more women to increase the generalizability of their findings to a larger population. Although this study cohort included only five female participants, the study was set up to control the menstrual phase, reducing confusion but making it more difficult for women to be recruited. Moving forward, Scheer and Vujović are also interested in better understanding the effects of the relationship between mealtime and bedtime on the energy balance.
“This study shows the impact of late versus early consumption. Here, we isolated these effects by controlling for confounding variables such as caloric intake, physical activity, sleep and light exposure, but in real life, many of these factors can themselves be influenced by meal times, “he said. supported Scheer. “In larger-scale studies, where tight control of all these factors is not possible, we must at least consider how other behavioral and environmental variables alter these biological pathways underlying obesity risk.”
Valentina Chiozzi, the nutritionist biologist, said: “Often the mistakes that are made at dinner have their origin in breakfast. Those who skip the morning meal or do it incorrectly tend to arrive in the evening with a lot of backward hunger. This habit leads to eating voraciously, quickly and without even tasting the food “.
“In this way, the sense of satiety arrives late, when by now more calories have been introduced than would be necessary to consume. In addition, in the evening there is more time at the table with the family, many add wine or dessert to pamper themselves a little after a tiring day. This can favor an accumulation of fat over time. In addition, we tend to eat late and this can disturb the quality of sleep, especially if the meal is abundant ”.
As for eating a sandwich for lunch, the expert observed: “The sandwiches that are generally found around are made with refined flours and are not always well balanced. Sometimes they are too much poor in nutrients because they are rich in calories, but low in vitamins, minerals and antioxidants. Vegetables are often scarce and the quality of flours too, and in many cases it happens to have to settle for greasy and heavy sandwiches.
Typically the sandwich is full on the spot, but then the lack of fiber makes itself felt and at the glycemic peak follows the reactive hypoglycemia that triggers hunger again after a couple of hours from the meal. Another aspect that comes into play is the psychological one. The sandwich is eaten quickly, perhaps standing up, so it feels more like a hunger breaker, rather than a real lunch. The result? It doesn’t satisfy like a full meal ”.
Eating late can create sleep disturbances, here’s how to avoid them: “The ideal is to have a light dinner (but not too much, to avoid waking up hungry in the middle of the night!), Composed according to criteria of the “healthy dish” proposed by the Harvard Medical School of Medicine.
In other words, it must be a full meal of all nutrients: good quality whole-grain carbohydrates, proteins, vegetables and fats, but with smaller portions than lunch. The ideal is to ensure that the energy intake of the day is progressively reduced, just as the popular saying goes: “have a king’s breakfast, a prince’s lunch and a poor man’s dinner”.
“The goal is to go to bed without dinner on the stomach and having completed a good part of the digestion. This guarantees a more restful and continuous sleep, without awakenings caused by the digestive processes that engage the body in activities that even at the hormonal level should be managed during the day. Let’s think about the secretion of melatonin, the hormone that regulates sleep. Its normal secretion by the pineal gland can be altered by excessively large meals, and this affects the quality of sleep ”.
“As a rule, in the evening it would be good limit fried foods or prepared with demanding cooking and rich in fat (bechamel, sauces, fillings with creams) because they lengthen digestion times and tire the liver. Same thing goes for alcohol ”.
“A healthy dinner could consist of a portion of Whole grains (perhaps a little less abundant than what is eaten at lunch), a portion of proteins cooked simply and a good portion of seasonal vegetables, perhaps enriched with a handful of oil seeds. They are rich in magnesium, a mineral that promotes relaxation and the synthesis of melatonin precursors ”.
“If there are no particular metabolic or digestive problems, a glass of wine at dinner is allowed. However, it should be borne in mind that alcohol can strain the liver and weigh down digestion. So it’s better not to abuse it and enjoy a good glass every now and then, as a small occasional pleasure! “.
Sometimes you feel the need to eat something delicious late: “If the evening meal is well structured and you take into account the time between dinner and when you go to bed to sleep, the evening snack shouldn’t be used. It would be better to avoid eating before going to sleep and to ensure a deep and restful sleep ”.
“If you want a pampering or a ritual to relax, an unsweetened herbal tea is much better! However, if you just can’t resist or have eaten too little for dinner or have to stay awake longer than expected, you can remedy with some almonds or other oily seeds. They are excellent and foster the sense of satiety and contentment! “.
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