Keeping a consistent eating schedule can help regulate your circadian rhythm—your body’s internal clock—and boost metabolic health, while spacing out your meals appropriately can aid blood sugar regulation and energy levels.

Here’s expert-backed advice on how to time your meals and craft your day’s eating schedule.

Why—and when—to eat breakfast

Professor of nutrition and registered dietitian Lisa Young advises eating breakfast within one to two hours of waking up to help you stabilize your blood sugar and reduce your risk of metabolic syndromes like Type 2 diabetes and obesity, and of cardiovascular disease and mortality. “If you’re not a morning person, it’s okay to keep it light,” she tells Fortune, but you should still eat a little something, even if you’re not that hungry.

“Skipping breakfast may lead to lower energy, overeating later, and poor concentration,” she explains, adding that having a balanced breakfast with complex carbohydrates, protein, and fat will support steady energy and better appetite regulation.

Not only will missing your morning meal impact how you feel, but it could also increase your risk of chronic disease: A 2019 review on meal timing and metabolic risk found that skipping breakfast was linked to greater instances of obesity. 

Young generally encourages eating most of your calories earlier in the day rather than later. One study observed that people who ate a bigger breakfast and smaller dinner had greater weight loss and waist circumference reduction—which is a key indicator of cardiometabolic health and mortality risk—versus those who ate a bigger dinner and smaller breakfast.

When you should eat lunch

Young advises having lunch between noon and 1:30 p.m., explaining that, ideally, you should aim to eat every three to five hours. If you find yourself feeling hungry between meals, or if meals are more than four to five hours apart, she encourages adding in protein- and fiber-rich snacks to hold you over.

You don’t want to go too long without eating—or skip meals altogether—Young says, because it can lead to fatigue, irritability, and overeating, and it may disrupt your metabolism and blood sugar balance.

The best time to eat dinner

Young suggests eating dinner before 7:30 p.m., or at least two to three hours before bedtime, in order to give your body time to digest and ensure your sleep won’t be disrupted. An early dinner—around 5:30 p.m.—can also be beneficial for your overall health, bringing the benefits of preventing heartburn and gastrointestinal distress.

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There’s also substantial data demonstrating that eating too late at night has been associated with a higher overall calorie intake and an increased risk for obesity. One study suggests that the hormone responsible for feeling full, leptin A, decreases later in the day, which can lead to late-night overeating. A 2022 study of two groups comparing eating later versus earlier also found that the later eating group’s odds of being hungry during the day doubled compared with the earlier group—and they were more likely to overeat starchy, salty foods and meat. The late eating group also burned fewer calories during the day than those in the early eating group.

Why keeping a regular eating schedule matters

Timing your meals isn’t only about how far apart to space them—it’s also important to keep to a regular eating schedule to aid your circadian rhythm, or your body’s internal clock. 

“Eating meals at consistent times best supports your internal clock and digestion,” Young says. Research reveals that irregular meal times can disrupt your circadian rhythm and your sleep, because circadian hormones, including cortisol and melatonin, interact with mealtimes and clue your body in on when to peak its energy and when to rest. Those hormones also play vital roles in regulating metabolic processes, as studies show that eating at inconsistent times can increase your risk of developing metabolic syndromes like diabetes.

While she advises generally following these guidelines, Young acknowledges that your eating pattern does depend, to a great degree, on your lifestyle, needs, and hunger levels.

“Tuning into your hunger and how you feel is most important,” she says. “What matters most is balanced, portion-aware eating that fits your lifestyle and keeps you energized. Ask yourself how you feel best.”

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