For the past few years, the concept of meal timing has been in the news frequently. While some sources support the idea, others say it doesn’t really matter. What’s the truth? Does when you eat make a difference?

Most of us eat over 15 or more hours each day, with more than a third of the calories being consumed occurring after 6:00 pm. In one study, 156 participants used a smartphone app to track what and when they ate or drank for three weeks. The only time when people ate very little was between 1:00 to 6:00 am. In addition, people met their calorie needs by about 6:30 pm, so everything after that was extra calories.

This is vastly different from how our ancestors lived. They ate their meals during daylight hours, which is thought to be linked to better health outcomes. The idea that our response to food varies at different times of day isn’t new. The ancient Chinese believed that energy flowed around the body in parallel with the sun’s movements and that our meals should be timed to reflect it.

An increasing amount of research shows that when you focus more on the timing of your meals (limiting the hours during the day when you eat), it can help you burn more fat, improve your health, and lose weight. One small study involving eight overweight men with prediabetes had them consume all their food during either a six-hour or a 12-hour window, starting at their usual breakfast time (between 6:30 and 8:30 am). After five weeks, the men on the six-hour plan were more insulin-sensitive, and their blood pressure was roughly 10 points lower. Also, they had less “desire to eat” in the evening, even though they had to stop eating by 2:30 pm at the latest.

Other studies have examined the early-in-the-day against the late-in-the-day eating concept. The breakfast diet is when you take in 700 calories at breakfast, 500 at lunch, and 200 at dinner. The dinner diet (our typical one) is when you take in 200 calories at breakfast, 500 at lunch, and 700 at dinner. The results show that the breakfast dieters had more than double the weight loss the dinner dieters had.

A different study randomly assigned participants to eat 50% of their calories at lunch and 20% at dinner or vice versa. The remaining calories were divided between breakfast and snacks. Also, both groups were told to cut calories and fat, eat more vegetables and fruits, and work toward an hour of exercise five days a week. After three months, the “big lunch” group had lost more weight. Further, the big lunch group had improvements in insulin resistance.

There are several reasons why meal timing is so beneficial. One is that the consistency and timing of your meals/snacks throughout the day helps keep your body energized. Your body needs a certain amount of energy each day and at different times throughout the day to thrive. Regular meals and snacks allow for more opportunities in the day to give our body the energy and nutrients it needs to function optimally. Your organs secrete hormones at various times of the day. If you’re not eating in line with those hormones, you could be feeding your body calories at a time when it’s less receptive to them.

For instance, your sensitivity to the hormone insulin, which enables the glucose from the food you eat to enter your cells and be used as fuel, is greater during the morning than at night. So, if you eat late, that glucose remains in your blood for longer, which over the long term can increase the risk of developing type 2 diabetes, where the pancreas no longer produces enough insulin.

Complex processes, such as the metabolism of fats or carbohydrates from the diet, require coordinating numerous processes occurring in the gut, liver, pancreas, muscle, and fatty tissue. If the conversation between these tissues becomes scrambled, they become less efficient. This is why it’s beneficial to consume most of your calories earlier in the day when your metabolism is at its most efficient.

One significant influencing factor is your circadian rhythm. This is the molecular clock that regulates the timing of pretty much every physiological process and behavior within your body, from the release of hormones and neurotransmitters to blood pressure and from the activity of your immune cells to when you feel more sleepy, alert, or depressed. It affects every cell of your body and keeps them in sync with each other and with the time of day outside through signals from a small patch of brain tissue called the suprachiasmatic nucleus (SCN).

The SCN is regulated by a subset of light-responsive cells at the back of the eye called intrinsically photoreceptive retinal ganglion cells (ipRGCs). Consistent meal timing has been shown to promote regulation of the circadian rhythm. Also, your body is getting fuel when it can use it. However, it’s essential not to graze all day. If you do, it prevents your body’s migrating motor complex (MMC) from firing. The MMC is an electromechanical wave of muscle contractions through your gut that acts to sweep through leftover undigested food. When we eat continuously, unable to do its job, and the build-up of residue can lead to increased bloating for some people.

When it comes to fasting, your body naturally does this each night, from whenever you finish eating to when you have breakfast in the morning. It should be somewhere between 8 – 14 hours each day. This allows your body to shift gears from its fed to fasted state, and you’ll experience metabolic benefits. The issue with late-night eating is that it extends the overall window during which food is consumed. This gives our digestive systems less time to recuperate and reduces the opportunity for our bodies to burn fat – because fat-burning only occurs when our organs realize that no more food is coming their way.

However, light isn’t the only thing that can change the timing of our clocks. Recent evidence suggests that the timing of exercise can tweak the clocks in our muscle cells. Another factor is sleep. An estimated 87% of the general population maintains a different sleep schedule on weekdays than on weekends. This means people tend to eat breakfast at least an hour later at the weekends, resulting in so-called “metabolic-jetlag.”

Meal Timing vs Nutrient Timing

Besides meal timing, you might have heard of nutrient timing (or anabolic window). The concept gained popularity in 2004 when Dr. John Ivy published Nutrient Timing: The Future of Sports Nutrition. Since then, many nutritional programs and books have promoted nutrient timing as the key method for losing fat, gaining muscle, and improving performance. This is why it’s been used by professional bodybuilders and athletes for decades. However, research shows that it has limitations for individuals who don’t fall into these groups.

Nutrient timing is based on the idea that the body is in the perfect condition for nutrient absorption within 15–60 minutes after exercise. The theory is based on two fundamental principles carbohydrate replenishment and protein intake. After a workout, if you give your body an immediate supply of carbs, it’ll help maximize glycogen stores, improving performance and recovery. Since working out breaks down protein, post-workout protein helps repair and initiate growth by stimulating muscle protein synthesis (MPS).

While these principles are correct to some extent, human metabolism and nutrition aren’t so simple. Research shows that timing may only be relevant if you train several times a day. Other research demonstrates that training with lower muscle glycogen is beneficial, especially if your goal is fitness and fat loss, which means that immediate replenishment may reduce the benefits you receive. Experts recommend that regular individuals focus on their total daily needs for protein, calories, and other nutrients rather than nutrient timing.

When it comes to the pre-workout window, it may actually be more critical. Depending on your goals, the correct timing for taking certain supplements may aid performance. Also, a well-balanced, easily digestible meal eaten 60–150 minutes before a workout may improve performance, especially if you have not eaten for several hours. However, if your goal is fat loss, training with less food may help you burn fat, improve insulin sensitivity and provide other important long-term benefits.

Another vital element is hydration. It’s important to drink around 12–16 oz of water and electrolytes before a workout. As far as vitamins go, they may affect workout performance. So, it may be best not to take them close to your activity.

Best Way to Time Meals

The easiest way to time your meals is to eat during daylight hours since your body is most sensitive to insulin during this time. This is why the calories you consume in the evening often get stored as fat. Your goal should be to eat during a 12-hour window each day, such as from 7 am to 7 pm. After the scheduled time, you stop eating for the day.

During the day, you need to eat regularly because this helps reassure your body that you do have access to adequate food. Consistent meal timing plays a crucial role in helping your body develop reliable hunger cues. It just takes time to develop and strengthen your ability to hear it. It’s vital to realize that some days you’ll need to eat more often and in larger portions, whereas other days you might find you aren’t as hungry. This is normal!

The other important element is how much you’re eating at specific times. The evidence suggests that our bodies may do best when we eat more in the morning than at night. So, you want to make sure to eat within 2 hours of waking up in the morning. This will provide your body with fuel to start the day. Your breakfast should be balanced and provide sufficient protein (starting at 20 g), quality carbohydrates from fruit/beans/whole grains, and essential plant-based fats (such as seeds, nuts, or avocados). This will keep you fuller longer, reduce blood sugar spikes throughout the day, and keep your hunger hormones in check.

If you find that you’re never hungry in the morning, try to have something small, so your body has some form of nourishment. It’s important to note that caffeine suppresses appetite.

After the first meal of the day, depending on what it was and how balanced, most people need to eat again every 3-4 hours. By including protein-rich, high-fiber foods, along with vegetables, fruits, and fats in all your meals, you’ll likely result in feeling full and satisfied for longer. One thing to keep in mind is that regardless of how long it’s been since you’ve last eaten, if you’re hungry, you need to eat.

Your goal should be to eat more in the morning and at lunch because you have a better chance of using that fuel as energy. So, even if you had a big breakfast, have a hearty lunch. Treat it how you’d normally treat dinner. Ideally, you’ll consume about 75 percent of your calories by 4 pm. You want to keep dinner light and lean and limit snacking after that. It’s good practice to give your body a chance to digest before bedtime by finishing your last meal or snack a few hours before going to sleep. The best thing is to eat a light dinner and then close the kitchen. Remember, earlier is better.

The key is to focus on consistency, daily calorie intake, food quality, and sustainability. You want to strive for greater consistency in the timing of your sleep and meals to help all your clocks get in sync. For sleep, go to bed at a time that will allow you to get the recommended seven to eight hours every day of the week. Getting more exposure to bright light during the day and dimming the lights in the evening can help shift the timing of your SCN.

If you have a structured meal plan, it makes eating well less stressful. Not only do you know when to eat, but you also know how much and what types of foods to eat to get the right balance of protein, fat, and carbohydrates. Just remember to leave room for spontaneity and social gatherings every once in a while.

Bear in mind that there’s no such thing as a perfect meal-timing schedule. Your perfect food schedule will be unique to you. Many factors can influence it, like your physical activity level, the type of exercise you participate in, the duration of your physical activity, and even genetics. So, while strict timing of meals and snacks is unnecessary, there are benefits to having a consistent eating schedule.

Your goal should be to rely on your hunger cues and your body’s signals to guide you on when to eat throughout the day. By aligning your meals with your natural circadian rhythm, it can help you function optimally and lead to many health improvements.