This eating pattern aligns with our circadian rhythms, the innate 24-hour clock that governs many aspects of our health, from our daily hormonal fluctuations and body temperatures to our sleep-wake cycles.
Because of the way our internal clocks are ticking, our bodies are ready 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 a.m. can have very different metabolic effects than the same meal eaten at 9 p.m.
This emerging area of research, known as chrono-nutrition, represents a paradigm shift in how nutrition researchers think about food and health. Instead of just focusing on nutrients and calories, scientists are increasingly looking at meal timing and finding it can have dramatic effects on your weight, appetite, risk of chronic disease, and health. your body’s ability to burn and store fat.
“It’s something that until recently no one in the nutrition field had considered – it’s always been what you eat and what is the energy content of your food or carbohydrates, proteins and fats. “, said Marta Garaulet, professor of physiology and nutrition. at the University of Murcia in Spain which studies mealtime and its effects on obesity and metabolism.
In today’s busy world, it’s common for people to skip breakfast and stuff themselves in the evening after a long day at work. The researchers say that when possible, it would be best to do the opposite – or at least space your dinner a few hours away from your bedtime.
Garaulet discovered in his research that even in his native country SpainFamous for its late-drinking culture, people who typically eat a heavy lunch at noon and a light dinner develop fewer metabolic problems than people who eat 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 consume 35 to 40% of our calories in the middle of the day. And even if we dine late, we don’t eat much.
A hearty breakfast and a light dinner
The timing of your meals is just one of many dietary factors that can influence your metabolic health. And for some people, like night shift workers, it’s impossible not to consuming meals late at night.
But for those whose schedules allow it, research suggests that having your biggest meal of the day in the morning or afternoon rather than the evening could be beneficial.
In a new study published in obesity journals, scientists reviewed data from nine rigorous clinical trials involving 485 adults. They found that people who were on diets where they consumed most of their calories earlier in the day lost more weight than people who followed the reverse. They also had greater improvement in their blood sugar levels, cholesterol levels and insulin sensitivity, 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 feeding schedule for six days. The schedule included breakfast at 8 a.m., lunch at noon, and dinner at 4 p.m.
On another occasion, they asked the same participants to follow a late meal schedule, with each meal pushed back four hours over a six-day period. The study was small but tightly controlled, involving 16 people who were closely monitored, provided all of their meals, and adhered to a strict sleep and wake schedule in a laboratory setting.
Why eating late makes you hungrier
Researchers found that despite eating the same foods and maintaining the same levels of physical activity, participants were significantly hungrier when they followed the late meal schedule.
A look at their hormone levels showed why: Eating later spiked their levels of ghrelin, a hormone that increases appetite, while simultaneously suppressing their levels of leptin, a hormone that causes satiety.
The study found that eating later allowed participants to burn less fat and fewer calories, and tricked their fat cells into storing more fat.
“To our surprise, we found that all three of these mechanisms were consistently altered in the direction that would promote weight gain,” said Frank Scheer, lead study author and director of the division’s medical chronobiology program. sleep and circadian disorders. at the Brigham and Women’s Hospital.
Other studies have had similar results. In a randomized trial at Johns Hopkinsscientists found that healthy young adults burned less fat and had a 20% increase in blood sugar when they dined at 10 p.m. compared to the same dinner on another occasion at 6 p.m.
“Clearly the timing of your meals matters — not just what you eat, but when you eat it,” said Jonathan Jun, associate professor of medicine at Johns Hopkins and study author. “Eating late makes you less glucose tolerant and also causes your body to burn less fat than if you had eaten the same food earlier in the day.”
How to follow an early eating schedule
Scientists who study mealtimes say the following strategies may help you optimize your health.
- Don’t skip breakfast. Garaulet and his colleagues discovered that skipping his morning meal increases your risk of obesity. It is in the morning that our body is ready to metabolize food. If you’re usually not hungry in the morning, eat something light and then eat a big breakfast. “Try to eat the majority of your calories in the morning or afternoon, but not in the evening,” Garaulet said.
- Morning carbs are better than end of day carbs. If you are going to eat sweets or simple carbohydrates like bread, pasta and pastries, it is better to do it in the morning or early afternoon, when we are most sensitive to insulin, rather than the night, Garaulet said.
- Try to eat dinner early in the evening. Start by moving your dinner at least an hour earlier than usual. Ideally, you should aim to have dinner at least two to three hours before you go to bed.
- Make dinner the smallest meal of the day. Even if you can’t eat dinner early, you should try to make breakfast and lunch your biggest meals of the day and dinner your smallest. If you usually eat a breakfast and a big dinner, change the order. You can make your dinner a vegetable-heavy meal to lighten it up. “Just try shifting more calories to breakfast and lunch,” said Courtney Peterson, associate professor in the department of nutritional sciences at the University of Alabama at Birmingham.
- Try to plan your meals at least five days a week. Sometimes it’s not convenient to eat a small dinner or an early dinner, and that’s okay. In studies, Peterson found that people who ate a light dinner five days a week instead of seven still experienced benefits like better blood sugar control and less daily fatigue. “Don’t think of it as hit or miss,” Peterson said. “Maybe some days you can’t make it because you go out to eat with your family. But on other days you can do it and that’s fine. It is important that you do what is convenient for you.
The biology of mealtimes
Scientists have discovered several mechanisms that explain why an early meal schedule is better for your health. Our body is more apt to secrete insulin, a hormone that controls blood sugar, in the morning.
We also tend to be more sensitive to insulin early 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 and less sensitive to insulin. At night, beta cells in the pancreas that produce insulin become sluggish and less sensitive to increases in blood sugar.
Another important factor is hormone-sensitive lipase, an enzyme that releases fat from our fat cells. This enzyme is usually most active at night, so it can provide our body with the energy needed 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. “We see a big difference between people who eat dinner, say, four hours before bedtime,” she said, “and people who eat dinner about an hour before bedtime.”
Do you have a question about healthy eating? E-mail EatingLab@washpost.com and we may answer your question in a future column.