There’s an obesity epidemic in our modern society, but while most of us blame unhealthy diets and a lack of regular exercise, there’s one thing that’s often overlooked: poor sleep.
When you’ve had a bad night’s sleep, you won’t have the energy to go to the gym and those donuts will be a lot harder to resist. But the sleep and weight loss connection goes deeper than that.
Not getting enough sleep can mess with your hunger hormones, your metabolism, and your fat loss. And not getting sleep at the right times for your body clock can also make or break your weight loss efforts.
Get your sleep and sleep timing right and you can maximize your weight loss efforts and make weight management much easier. Get them wrong, however, and you’ll not only struggle to lose weight, you could gain additional weight.
Below, we’ll explain the connection between sleep and weight loss, and how you can improve your sleep to maximize your weight loss.
The link between sleep and weight is a strong one. Here’s how a poor night’s sleep is reflected in your waistline.
When you don’t get enough sleep, your hunger hormones are thrown out of whack. Ghrelin, the hormone responsible for hunger, rises, while leptin levels, the hormone responsible for satiety, fall. So, you’ll have a larger appetite, leading to an increased food intake.
Your self-control takes a hit after sleep loss, meaning it’s much harder to resist high-calorie, high-carbohydrate junk foods. And your endocannabinoid system, involved in appetite regulation and the reward centers of your brain, is heightened, meaning your cravings for these foods go up, too.
Sleep deprivation also impacts how well the hypothalamus region of your brain works, and this region plays a huge role in appetite regulation and energy expenditure.
Finally, there’s the simple fact that if you’re awake for longer, there’s more opportunity to eat. You may burn more calories being awake and active compared to being asleep, but research still shows you’re more likely to consume more calories than you burn by staying awake longer.
And science proves it. Research shows people can eat 385 extra calories a day after a night of partial sleep restriction.
A meta-analysis on sleep and obesity found people who were short sleepers (defined as sleeping less than five hours a night) had increased odds of being obese. And it doesn’t take much to increase those odds.
The research showed a reduction of just one hour of sleep per day was associated with a roughly 0.35 kg/m² increase in body mass index (BMI).
Sleep deprivation looks different for all of us, though. Everyone has an individual sleep need, the amount of sleep you need each night. It’s determined by genetics, just like height and eye color, and it’s not eight hours for everyone.
One study suggests the average sleep need is 8 hours 40 minutes, plus or minus 10 minutes or so, but 13.5% of the population may need 9 hours or more sleep a night.
You can use the RISE app to take the guesswork out of it and find out your sleep need down to the minute. The app uses a year’s worth of your phone use behavior and proprietary sleep-science-based models to work out your sleep need.
Read more about how to calculate your sleep need here.
When you don’t get enough sleep, your energy levels and motivation take a hit, making it much harder to get out for a run or hit the gym, or do much physical activity and calorie burning at all.
Beyond workouts, you burn fewer calories by default when you get insufficient sleep. Research has found resting metabolic rate — the rate your body burns calories while resting, the biggest part of how many calories you burn a day — is significantly lower after getting four hours of sleep for five nights.
So, when sleep-deprived, you end up eating more calories and burning fewer calories, a recipe for weight gain.
A lack of sleep causes your body to store more fat, even if you’re not eating more calories.
Research found short sleepers (defined here as habitually getting less than 6.5 hours a night) produced about 50% more insulin and had about 40% lower insulin sensitivity than average sleepers (defined as getting 7.5 to 8.5 hours a night).
Increased insulin levels can lead to insulin resistance, which puts you at risk of type 2 diabetes and obesity. When your body becomes resistant to insulin, you can’t absorb glucose as easily. You may end up with excess glucose in your blood, and when this isn’t used as fuel, it can be stored as fat in the body (especially around the belly), causing weight gain this way.
So, not only does sleep deprivation cause you to eat more calories, burn fewer calories, and store more body fat, it can also sabotage other things you’re doing to try and lose weight.
For example, one study looked at overweight participants who underwent caloric restriction for two weeks while either getting 8.5 or 5.5 hours of sleep a night. We’re sure you can guess who lost the most weight.
The group who got 8.5 hours of sleep lost more body weight than the 5.5-hour group, and they experienced less hunger, too.
The researchers concluded: “Lack of sufficient sleep may compromise the efficacy of typical dietary interventions for weight loss.”
So, if you’re cutting calories and dieting, you need to meet your sleep need to make the most of this weight loss strategy.
If you’re trying to lose weight, chances are you’re trying to lose belly fat, too. And that, too, is linked to poor sleep.
Regularly sleeping for five hours or fewer a night has been linked to both obesity and abdominal obesity. People who regularly sleep for six hours or fewer a night also tend to have higher BMIs, fat percentage, and abdominal circumferences than those who sleep for seven to eight hours.
And a new study from 2022 found when people slept for four hours a night for 14 nights, they ate more calories, gained more weight, and gained more belly fat, both subcutaneous fat (the fat found just under the skin) and visceral fat (the fat around the organs) than the control group.
Sleep deprivation causes an increased level of the stress hormone cortisol, and high cortisol levels can cause your body to store fat, especially around the belly area. Sleep deprivation can also lead to insulin resistance, which not only ups your odds of type 2 diabetes, it can trigger your body into storing more fat around — you guessed it — the belly area.
It’s not just about how long you sleep for, however. Low sleep efficiency (being awake a lot of the time you’re in bed) has been linked to obesity and abdominal obesity. And reduced or disturbed sleep has been linked to glucose intolerance and insulin resistance, which are linked to type 2 diabetes, weight gain, and belly fat again.
And beyond sleep, those who live out of sync with their circadian rhythms (more on what this means soon) are more at risk of obesity and abdominal obesity.
It’s not just about getting enough sleep, you also need to get it at the right times for your body — and that’s where your circadian rhythm comes in.
Your circadian rhythm is your body’s internal biological clock. It runs on a roughly 24-hour cycle and dictates when you feel awake and sleepy, when your body produces certain hormones, and when your body temperature fluctuates, among other things.
You might be meeting your sleep need, but if you’re living out of sync with your circadian rhythm, you’ll still struggle to lose weight, and may even gain more weight.
But, it’s more than just sleeping. There’s one master clock in your brain, but there are also body clocks located in almost every tissue and organ system in your body, including in your immune system, metabolism, and digestive system. These clocks are called peripheral clocks and they can get out of sync with your master clock.
Light is the most powerful zeitgeber — something that times your circadian rhythm to the outside world — but eating can also have this effect. When you eat at odd times, like late at night or at irregular times each day, you can cause your peripheral clocks to become out of sync with your masterclock, which then in turn throws your metabolic processes off course.
What’s more, your peripheral clocks adjust to changes much more slowly than your master clock. This is what’s behind the digestive issues that often come with jet lag and why even those who just eat late dinners on the weekend aren’t immune.
How does this all lead to weight gain? Research shows those who sleep and eat about 12 hours out of sync with their circadian rhythms (common in night shift workers) have 17% decreased leptin, 6% increased glucose, and 22% increased insulin — a recipe for overeating and weight gain.
Their sleep efficiency was also reduced by 20%, meaning they’re vulnerable to all the weight gain risks of sleep deprivation, too.
Even if you’re not a night shift worker, you could still be sabotaging your weight loss by being out of sync with your circadian rhythm.
A 2021 study looked at mice who were three hours out of sync. The mice out of sync gained more weight, had higher blood pressure, and fattier livers than those in sync with their circadian rhythms, even when they were both fed the same high-fat and high-sugar diet.
When the mice got back in sync with their circadian rhythms, however, they were no longer as susceptible to the poor health outcomes of their unhealthy diet.
“When the external world doesn’t match the internal body’s cycles, metabolism pays the price,” said the study’s senior author, Mitchell A. Lazar. “We saw this in our study, and we believe that this happens similarly when people work odd hours that don’t align with how human bodies are wired.”
Beyond working late or at night, you could be out of sync with your circadian rhythm if you have social jetlag, which is when you sleep later on the weekends compared to the week. These irregular sleep times mess up the timing of your circadian rhythm.
You’re not alone if you have social jetlag, though, about 87% of us have it and go to bed at least two hours later on the weekend than in the week. But having social jetlag is associated with having a higher BMI, and associated with a two-fold increased risk of metabolic syndrome, which includes diabetes, high blood pressure, and obesity.
Beyond sleeping at the right times and having a regular sleep pattern, make sure you’re eating in sync with your circadian rhythm, too.
The RISE app predicts your circadian rhythm each day and shows you when your body naturally wants to wake up, wind down for bed, and be asleep. You can then sync up your sleep and meal times to match.
Got your diet plan and gym membership ready? Don’t forget about your sleep, too. Now we’ve explained the link between sleep and weight loss, it’s time to learn how you can get adequate sleep at the right times for you to help you lose the pounds, maintain a healthy weight, and protect yourself from weight gain.
Sleep debt is the running total of how much sleep you owe your body. In the RISE app, we measure it over the past 14 nights.
For example, if your sleep need is 8 hours 30 minutes, but you’ve only been getting 7 hours a night recently, you’ll have built up quite a bit of sleep debt.
The good news about sleep debt is you can pay it back. Here’s how:
By keeping sleep debt low, you’ll be reducing the chances of increased ghrelin, insulin, and cortisol from sleep deprivation leading to weight gain. Plus, you’ll have more self-control to stick to your diet and more energy to hit the gym.
Need proof that more sleep can help with weight loss? New research from 2022 found that when participants who slept for 6.5 hours a night increased how long they slept by about 1.2 hours a night, they managed to reduce their caloric intake by 270 calories a day. This would translate to 26 pounds of weight loss over three years.
“Many people are working hard to find ways to decrease their caloric intake to lose weight — well, just by sleeping more, you may be able to reduce it substantially,” said researcher Esra Tasali.
The RISE app can work out how much sleep debt you’re carrying and keep track of it as you pay it down.
Don’t let a messed-up body clock stop you from losing weight. You can live in sync with your circadian rhythm by:
By living in sync with your circadian rhythm, you’ll keep your hunger hormones and insulin in check, have an easier time falling asleep at your desired bedtime (to avoid the ill effects of sleep deprivation), and protect yourself from a whole host of health issues.
If your circadian rhythm doesn’t match your lifestyle — perhaps you’re a night owl who needs to be up early for work — you can learn how to reset your circadian rhythm here. Don't know what chronotype you are? Learn more here.
Sleep hygiene is the set of daily habits you can do to fall asleep faster and reduce how often you wake up during the night. This will help you both keep your sleep debt low and stay in sync with your circadian rhythm, by helping you fall asleep at the right time.
Here’s what to do:
In the 2022 study we mentioned above, study participants were able to increase their sleep duration, and therefore reduce their daily caloric intake, just by improving their sleep hygiene.
You can learn more about sleep hygiene here. You can also turn to RISE to discover 20+ sleep hygiene habits and the exact time you should do them based on your circadian rhythm each day.
The connection between sleep and weight loss is a strong one. When you don’t get enough sleep everything from your hunger hormones to your fat storage is impacted, leading to overeating, weight gain, and belly fat. You may find it harder to resist unhealthy foods and motivate yourself to go to the gym, and you may lose less weight even when dieting. But good sleep doesn’t often feature in weight loss programs.
Beyond getting enough sleep, however, you need to get it at the right times for you i.e. in sync with your circadian rhythm.
By keeping sleep debt low and living in sync with your circadian rhythm, you can make sure you don’t gain extra weight, make losing weight easier, and keep the pounds off once you’ve lost them.
The RISE app can help. It’ll tell you your unique sleep need, how much sleep debt you have, and predict your circadian rhythm each day, so you can match your sleep and meal times to it. Plus, the app can guide you through 20+ sleep hygiene behaviors to make sleep, and therefore weight loss, even easier.
Yes, sleep can affect your weight loss. Sleep deprivation can cause you to eat more calories, burn fewer calories, store more fat, and lose less weight, even when dieting.
Yes, sleep affects your weight. Not getting enough sleep can cause you to eat more calories, burn fewer calories, and store more fat and belly fat, and it increases your odds of obesity.
Sleep is important for weight loss as it helps to keep your hunger hormones, glucose tolerance, and cortisol in check. It also keeps your self-control and energy high, so you’re more likely to eat well and exercise.
You need to get your individual sleep need, the genetically determined amount of sleep you need each night, to maximize weight loss. The average sleep need is 8 hours 40 minutes, plus or minus 10 minutes or so, but 13.5% of us may need 9 hours or more sleep a night. The RISE app can work out your individual sleep need. Research shows short sleep duration is linked to weight gain.
The best time to sleep to lose weight is a time that matches your circadian rhythm and is at roughly the same time each night. Later sleep times have also been linked with obesity.
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