Losing weight is hard. You need to think about working out, eating the right things, and getting enough sleep. But as well as what you eat, don’t forget to think about when you eat.
Eating too close to bedtime or at night can not only make losing weight hard, it can actually cause you to gain more weight. And that’s not to mention the whole host of other health issues late-night eating can lead to.
Below, we’ll dive into why late-night eating can sabotage your weight loss efforts and what time you should aim to be done with dinner each day to stop that from happening.
Many of us know reducing calories, exercising, and getting enough sleep can help us lose weight. But you might be sabotaging your weight loss efforts simply by eating your last meal too late in the day.
There’s a few reasons for this:
Let’s dive into those three things in more detail.
Firstly, our food choices tend to be unhealthier in the evenings. Our self-control has often been used up on other things earlier in the day, so we tend to reach for junk food or sugary snacks.
One study found later timing of your last meal, eating more frequently, and a shorter duration between your last meal and sleep were linked to consuming a higher number of calories. The research concluded that later meal timings, especially close to sleep, could lead to weight gain due to eating more calories each day.
It’s not just the excess calorie intake that can cause weight gain, though. Calories may be used more efficiently in the morning than in the evening, and your body is better at digesting food when it expects you to be active, i.e. during the day.
One study found higher body mass index (BMI) was linked to shorter sleep duration, later sleep timing, and eating food after 8 p.m. But even when sleep duration and timing were accounted for, eating after 8 p.m. was still associated with having a higher BMI.
Your circadian rhythm is your body’s internal biological clock. It runs on a roughly 24-hour cycle and dictates things like your sleep-wake cycle, when your body produces certain hormones, and when your body temperature fluctuates. You have one master body clock in your brain and peripheral body clocks found elsewhere in the body, like in the immune system, muscles, and digestive system.
Light is the main influence on the timing of the master clock, but meal timing can influence the timing of your peripheral clocks.
So, eating too late in the day (misaligning your meal timing with your light timing) can cause your body clocks to become out of sync with each other, which in turn can throw your metabolic processes off course. Over time, this desynchrony increases your risk of obesity and abdominal obesity.
One study found when mice were fed a high-fat diet out of sync with their circadian rhythms they gained significantly more weight than mice fed the same diet in sync with their circadian rhythms. For humans, the takeaway is it’s likely better to eat during the day, instead of at night when our bodies aren’t expecting food.
Shifting your calories as well as your meal timings earlier could also help you lose weight. People who ate a high-calorie breakfast lost more weight over a 12-week program than people who ate a high-calorie dinner.
As a general rule: finish up dinner two to three hours before bed. This will keep your body clocks in sync and also mean late-night meals won’t disturb your sleep — which can also lead to weight gain.
The RISE app can tell you when to have your last meal based on your circadian rhythm each day.
Time-restricting eating (TRE) is when you only eat during a limited window each day, such as between 8 a.m. and 8 p.m. Most of the time, this is in sync with your circadian rhythm and not too late in the day.
Research suggests eating all your meals within a 12-hour window prevents excessive weight gain. And yet more research shows time-restricted eating results in an average weight loss of 3% and a loss of fat mass, even without any caloric restriction.
Time-restricted eating has also been shown to boost immune function, reduce infection, and reduce inflammation. Helping individuals avoid the clock desynchrony that comes from differently-timed meal and light signals is one reason why TRE might help with weight loss and more.
Intermittent fasting often goes one step further. You may eat only during shorter windows of time, such as six or eight hours, or you may cut your calories as well as eating within set hours. There’s no set definition for time-restricted eating and intermittent fasting, and the two are often used interchangeably.
A 2018 study found intermittent fasting with a six-hour feeding window and all meals eaten before 3 p.m. improved insulin sensitivity, blood pressure, oxidative stress, and reduced appetite. And these benefits were found even when participants didn’t lose any weight.
So, you may choose to finish up your last meal even earlier to have a longer window when you’re not eating overnight. For example, if you have breakfast at 7 a.m., you’d want to finish dinner by 7 p.m. to be eating within a 12-hour window.
Heads-up: More research needs to be done on the long-term effects of time-restricted eating and intermittent fasting.
Leptin is a hormone responsible for satiety. That too runs on a circadian rhythm, with a peak around 2 a.m. (chronotype dependent), when you would naturally be sleeping, and the lowest point around noon (again, chronotype dependent), when you would naturally be awake and active.
In simple terms, that means you should feel hungry during the day and shouldn’t feel hungry at night, which allows you to sleep soundly.
But when you don’t meet your sleep need (the genetically determined amount of sleep you need) leptin levels are lower and ghrelin, the hormone responsible for hunger, is higher. This leads to overeating and weight gain.
But sleep loss isn’t the only thing that affects leptin levels. Overweight individuals have a flattened leptin circadian rhythm, meaning that peaks and dips aren’t as strong, and they may feel hunger during the night.
This, of course, may lead to overeating, weight gain, and eating during the night, which promotes circadian misalignment and sleep loss.
Use RISE to find out your individual sleep need and start aiming for this each night to keep your hunger hormones in check. Learn more about why you're always hungry here.
Getting enough sleep each night is integral to losing weight as sleep deprivation messes with your hunger hormones, increasing ghrelin and decreasing leptin.
But the time of day you eat also has an impact on your sleep. Eat too late in the day and you’ll increase your odds of heartburn and digestive issues keeping you up, and late meals also make it more likely you’ll wake up during the night, too.
All this makes it harder to meet your sleep need, and when you don’t meet your sleep need, you’ll start building up sleep debt. This is the running total of how much sleep you owe your body.
In the RISE app, we measure it over the past 14 nights. You can use the app to find out your individual sleep need (it’s not eight hours for everyone!) and how much sleep debt you’re carrying.
The sleep debt you have, the more likely you are to overeat and gain weight. Your diet will also take a hit: you’ll be craving unhealthy foods and have less self-control when you’re sleep deprived, too.
Finishing up your last meal two to three hours before bed will not only help with weight loss directly, it’ll help you get the sleep you need each night, which will also help with weight loss.
Eating and sleeping at the wrong times can change how your body stores fat. When you’re living out of sync with your circadian rhythm, your glucose tolerance is lowered. This means your body can’t dispose of glucose in your blood efficiently, and any glucose it can’t use may be stored as fat, especially around the belly area. Impaired glucose tolerance is also associated with insulin resistance, a risk factor for obesity and type 2 diabetes.
Your circadian rhythm anticipates when you’ll be awake and asleep and adjusts your metabolism to match. Everything from saliva production to colon movements to insulin sensitivity follows a circadian rhythm.
Your glucose tolerance does too, and it’s lower in the evening and at night than in the morning. That means the same meal can impact your glucose levels differently depending on when you eat it.
One study had participants eat the same meal at 8 a.m. and 8 p.m., then sleep at night. Glucose tolerance was 17% lower in the evening than in the morning. Participants then ate at the same times, but slept during the day, and their evening glucose tolerance became even worse.
This shows glucose tolerance is dictated by a circadian rhythm, but also that living out of sync with your circadian rhythm can lower glucose tolerance, which could increase your risk of diabetes and obesity.
What’s more, eating when you have high melatonin levels can impair your glucose tolerance as the hormone reduces your insulin resistance.
Melatonin helps to prime your body for sleep, so you’ll have high melatonin levels late in the evening and at night. You may also have high levels if you’re out of sync with your body clock and your body is producing melatonin during the day, or if you take melatonin supplements during the day.
You can learn more about what melatonin does here.
Although there’s no set time for when you should stop eating to improve glucose tolerance, it’s yet another reason to keep meal times to during the day, and to avoid eating in the lead-up to bedtime.
If you find yourself reaching for ice cream or popcorn at the end of the day more out of habit than hunger, here’s what you can do:
Once you’re done with your last meal for the day, brush your teeth. You’ll be much less likely to reach for an evening snack if you’ve already tended to oral hygiene and don’t want to redo that again.
You’re going to feel late-night hunger pangs if you haven’t eaten enough or eaten well during the day.
Spread your food intake across the day, so you eat less in the evening. An October, 2022 study showed participants who front-loaded their food intake had greater satiety and lower hunger, allowing them to reduce calorie intake later in the day. Make sure you’re eating breakfast and lunch — don’t skip them in an attempt to hit your weight loss goals or when you’re too busy at work.
Avoid junk food and sugary snacks, which don’t do much for you nutritionally. Eat a diet rich in veggies, fruits, complex carbohydrates, healthy fats, and protein.
If you do find yourself hungry late at night and can’t wait until breakfast, opt for a healthy snack, like low-fat yogurt or fresh fruit.
To help you lose weight and break the habit of late-night eating, consider time-restricted eating or intermittent fasting.
You might choose a 12-hour eating window that starts with a 7 a.m. breakfast, and therefore has to end by 7 p.m. Or you might opt for an even shorter window, finishing dinner earlier.
The RISE app can tell you the best time to have your last meal depending on your circadian rhythm each day. You’ll get a reminder three hours before your Melatonin Window each night.
Your Melatonin Window is the one-hour window of time when your body’s rate of melatonin will be at its highest. This is the ideal time to go to bed as melatonin primes the body for sleep.
Sometimes you don’t even realize you’re reaching for a post-dinner snack, and a helpful reminder is all you need.
Often, we reach for late-night snacks because it feels relaxing to snack on chips or chocolate in front of the TV. If this is the case for you, swap mindless eating for other relaxing late-night activities.
Set up a wind-down routine that involves things like reading, journaling, listening to music, or doing yoga. Brushing your teeth can be included here too to reduce the temptation to snack.
Use the RISE app to build your ideal evening routine, and get a reminder at the time you should start winding down for bed.
The bottom line is eating too close to bedtime can lead to everything from weight gain to diabetes to disrupted sleep, which itself can cause you to gain weight.
To maximize your weight loss efforts, you need to think about when you eat, as well as what you’re eating. And getting the timing of meals right can help with weight management once you’ve shifted the pounds, as well as give you plenty of other health benefits.
Aim to finish up your final meal two to three hours before bed, and consider finishing up even earlier than this to boost your weight loss efforts further.
Use the RISE app to see when you should have your final meal each day based on your individual circadian rhythm. The app can also guide you through 20+ sleep hygiene habits to help you meet your sleep need each night and live in sync with your circadian rhythm, two things that also help to maximize weight loss.
Eating before bed can make you gain weight. You tend to go for unhealthier foods late at night and late-night eating can throw your body clocks out of whack and disturb your sleep, both of which can lead to weight gain.
Eating late can cause belly fat as it disrupts sleep, messes up your body clocks, and people tend to go for unhealthier food options late at night. Stop eating two to three hours before bed to stop this from happening.
There’s no set time you should stop eating to lose belly fat, but, as a guideline, you should avoid eating two to three hours before bed to stop it from disrupting your sleep and body clocks, which can cause belly fat gain. Studies show early dinners can help people lose weight.
The benefits of not eating at night include higher odds of falling asleep faster, staying asleep all night, and staying in sync with your circadian rhythm – all things that help you maintain your weight, give you energy, and improve your mental and physical well-being.
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