This pattern of eating aligns with our circadian rhythms, the innate 24-hour clock that governs many aspects of our health, from daily hormonal fluctuations and body temperatures to our sleep-wake cycles.
Because of our way Internal clocks are working, and our bodies are primed to digest and metabolize food early in the day. As the day progresses, our metabolisms become less efficient. Studies show that a meal eaten at 9 am can have very different metabolic effects than the same meal eaten at 9 pm
This emerging area of research, known as chronic nutrition, represents a paradigm shift in how nutrition researchers think about food and health. Instead of focusing solely on nutrients and calories, scientists are increasingly looking at meal timing and discovering that it can have surprising effects on your weight, appetite, chronic disease risk, and your body’s ability to burn and store fat.
“This is something no one has looked at until recently — it’s always what you’re eating, and what the energy content of your food is or carbohydrates, protein and fats,” said Marta Garolette, professor of physiology and nutrition. at the University of Murcia in Spain where he studies meal timing and its effect on obesity and metabolism.
In today’s busy world, it is common for people to skip breakfast and binge at night after a long day at work. Whenever possible, researchers say it would be best to do the opposite — or at least leave dinnertime for a few hours of your bedtime.
Garaulet found in her research that even in her native Spain, which is famous for its late-eating culture, people who typically eat a big lunch in the middle of the day and a light dinner have fewer metabolic problems than people who consume a lot of calories at night.
“In Spain, our main meal is in the middle of the day, from 2 to 3 p.m.,” she said. “We eat 35 to 40 percent of our calories in the middle of the day. And even though we eat dinner late, we don’t eat as much.”
Big breakfast and light dinner
When you eat your meals is just one of the many nutritional factors that can affect your metabolic health. And for some people, like night shift workers, it’s impossible not to eat late-night meals.
But for those whose schedules allow, research suggests that eating the largest meal of the day in the morning or afternoon rather than at night may be beneficial.
in a new study Posted in Obesity ReviewsThe scientists looked at data from nine rigorous clinical trials involving 485 adults. They found that people who were assigned to follow a diet in which they consumed most of their calories early in the day lost more weight than people who did the opposite. They also had greater improvements in blood sugar, cholesterol levels, and insulin sensitivity, which is a marker of diabetes risk.
in another study Published in Cell Metabolism In October, scientists recruited a group of adults and examined what happened when they followed an early eating schedule for six days. The schedule included breakfast at 8 am, lunch at noon, and dinner at 4 pm
On a separate occasion, they had the same participants follow a late-eating schedule, delaying each meal four hours over the course of six days. The study was small but tightly controlled, and involved 16 people who were closely monitored, fed all of their meals, and kept a strict sleep-wake schedule in a lab setting.
Why eating late makes you hungrier
The researchers found that despite eating the same foods and maintaining the same levels of physical activity, the participants were significantly hungrier when they followed a delayed eating schedule.
A look at their hormone levels showed why: Eating later caused levels of ghrelin, a hormone that increases appetite, to rise, while at the same time suppressing levels of leptin, a hormone that causes satiety.
The study found that eating later caused the participants to burn less fat and fewer calories, prompting their fat cells to store more fat.
said Frank Scheer, senior author of the study and director of the Medical Chronobiology Program in the division of sleep and circadian disorders at Brigham and Women’s Hospital.
Other studies have had similar results. In one randomized trial at Johns HopkinsScientists found that healthy young adults burned less fat and had a 20 percent increase in blood sugar levels when they ate dinner at 10 p.m. compared to when they ate the same dinner on another occasion at 6 p.m.
“Obviously, the timing of your meals matters — not just what you eat, but when you eat it,” said Jonathan John, assistant professor of medicine at Johns Hopkins University and an author of the study. “Eating later makes you less glucose tolerant and makes your body burn less fat than if you ate the same food earlier in the day.”
How to follow an early eating schedule
Scientists who study meal timing say the following strategies can help you improve your health.
- Don’t miss breakfast. Garaulet and her colleagues found that skipping your morning meal It increases the risk of obesity. Morning is when our bodies are primed to metabolize food. If you don’t usually feel hungry in the morning, eat something light, and then have a big lunch. “Try to eat the majority of your calories in the morning or afternoon, but not at night,” Garaulet said.
- Carbs in the morning are better than carbs late in the day. If you’re going to eat sweets or simple carbohydrates like bread, pasta, and pastries, it’s best to do so in the morning or early afternoon, when we’re most sensitive to insulin, rather than at night, Garaulet said.
- Try to eat dinner early in the evening. Start moving dinner at least an hour earlier than usual. Ideally, you should aim to eat dinner at least two to three hours before bed.
- Make dinner the smallest meal of the day. Even if you can’t eat an early dinner, you should try to make breakfast and lunch the largest meals of the day and dinner the smallest. If you are used to eating a small lunch and a large dinner, change the order. You can make your dinner a meal rich in vegetables to brighten it up. “Just try to shift more calories into breakfast and lunch,” said Courtney Peterson, associate professor in the department of nutritional sciences at the University of Alabama at Birmingham.
- Try to time meals at least five days a week. Sometimes it’s not practical to eat a small or early dinner, and that’s okay. In studies, Peterson has found that people who eat light dinners five days a week instead of seven still gain benefits such as better blood sugar control and less daily fatigue. “Don’t think of this as all or nothing,” Peterson said. “Maybe some days you can’t do that because you go out to eat with your family. But then other days you can and it’s great. It’s important to do what’s practical for you.”
The biology of meal timing
Scientists have discovered several mechanisms that explain why an earlier eating schedule is better for your health. Our bodies are better able to release insulin, a hormone that controls blood sugar levels, in the morning.
We also tend to be more sensitive to insulin earlier in the day, which means our muscles are better able to absorb and use glucose from our bloodstream. But as the day progresses, we become less sensitive to insulin. By nightfall, the beta cells in the pancreas that produce insulin become sluggish and less responsive to the rise in blood sugar.
Another important factor is hormone-sensitive lipase, an enzyme that releases fats from our fat cells. This enzyme is usually more active at night so it can provide our bodies with energy to keep our organs functioning while we sleep.
But Garaulet found that eating late at night suppresses this enzyme — essentially preventing your body from burning fat. She said: “We see a big difference between people who eat dinner say four hours before they go to bed, and those who eat dinner about one hour before they go to bed.”
Do you have a question about healthy eating? e-mail EatingLab@washpost.com We may answer your question in a future column.