Though there are many conflicting ideas about how best to lose weight, leading to a slew of diet options – low-carb, low-calorie, keto, and paleo, to name a few – one factor that is often ignored is the timing of your meals. The way many of these diets are designed, it doesn’t matter when you eat, as long as you control what you eat. However, recent studies have shown that this may be a mistake: Eating meals later in the day may contribute to difficulty attaining and maintaining a healthy weight.

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The Most Important Meal

For many Americans, the largest meal of the day is dinner/supper. Although in previous generations – and even today, in many European countries – lunch was the largest meal, the automation of agriculture combined with the modern prevalence of office and factory jobs means that many people don’t have the time or resources to dedicate to a large midday meal, let alone breakfast. Since the bustle of getting families out the door to work or school often leaves even less time for a hearty breakfast, the evening meal typically becomes the caloric leader for the day.

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However, they say breakfast is the most important meal for a reason. Research has shown you should set aside that extra time for a healthy meal in the morning for the best energy regulation. A clinical study recently published in Cell Metabolism indicated that participants who ate the bulk of their calories earlier in the day fared better in terms of energy expenditure and appetite suppression than those who ate more later in the day, especially those who ate their evening meals close to bedtime.

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The study followed 16 participants, all classified as overweight or obese, who were assigned one of two diets: half ate all meals earlier in the day, with breakfast being the most calorically dense, lunch less so, and dinner the lightest, while the other half did the reverse, delaying mealtimes by 250 minutes and eating the most calories during dinner. The participants then traded diets midway through the study.

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Effects of Eating Before Bed

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Although the “midnight snack” is a nearly ubiquitous concept in modern society, eating late at night may actually be negatively affecting your sleep, your metabolism, your energy levels, and your appetite, all of which have a direct impact on your ability to maintain a healthy weight.

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Some effects of late-night eating found by this study include lowered body temperature throughout the day, reduced calorie expenditure, increased storage of fat as adipose tissue, and reduced breakdown of that adipose through lipolysis. Researchers also tracked the participants’ levels of ghrelin, the hormone that tells your body it is hungry, and leptin, the hormone that tells your body it is full. They found that the former was increased and the latter decreased in those with later eating habits. Participants also self-reported varying feelings of hunger or satiation relative to their assigned daily calorie distribution, confirming these findings.

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Although some studies contradict findings on metabolism and energy usage variations after eating late at night, there seems to be a broad consensus that eating the bulk of your calories earlier in the day contributes to appetite suppression throughout the rest of the day. This decrease in appetite may lead to weight loss outcomes by reducing the total calories consumed throughout the day. On the other hand, participants who ate more calories later in the day experienced increased appetite and got less sleep.

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Because sleep deprivation reduces self-control and increases impulsivity, sleep deprivation may make it harder to maintain dietary restrictions. Tiredness and sleep loss also make us crave junk food, which researchers theorize is because of the quick energy provided by sugars and simple carbohydrates often found in those foods.

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This makes weight loss and maintenance more difficult. Conversely, though, if you’re attempting to gain weight to reach healthy levels, it may be helpful to shift your eating schedule later in the day and consume more calories at night to stimulate your appetite.

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Timing Is Relative

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It’s important to note that for the purposes of these studies, participants were put on a strictly timed sleep-wake cycle. However, studies have shown that some people function better on a slightly different circadian rhythm, being more active late at night and sleeping through the morning, as opposed to waking up early in the morning and going to sleep shortly after dark. This delayed sleep cycle is particularly prevalent in neurodivergent teens and adults.

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Bear in mind that when applying the findings of these studies, what is considered “early” or “late” is relative to your personal circadian rhythm, with “early” referring to the time closest to when you wake, and “late” referring to the time closest to when you go to sleep.

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Current research, meanwhile, may be limited by the available sample sizes, the lifestyles of participants able to commit to a multi-week inpatient study, and significant gender imbalances.

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Safe Dieting

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You should always talk to your doctor or a qualified dietician before altering your food habits in any significant way, especially if you have any health conditions or take any medications that might be affected by the change in diet. Everybody is different, but your doctor can help you choose the diet that is best for your body type and health needs.

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