Push-ups or plank position? Lunges or burpees? High-intensity interval training (HIIT workouts) or something more low impact? When it comes to burning belly fat, which one should you choose? Our answer isn’t any of these, and it’s not actually a core exercise at all.
What if we told you there’s a way to lose belly fat that doesn’t involve a gym membership? And no, it’s not an hour of cardio every morning or 100 crunches a day, either. In fact, you can do this activity in your sleep — literally.
Science is finding out just how important sleep is to our weight and body fat. Getting the right amount of sleep for you each night can help you lose the pounds and keep them off, including around the belly area. But it’s not just about how long you spend in bed each night. Sleeping at the right times, or in other words syncing up with your circadian rhythm, is also integral to keeping belly fat at bay.
Below, we dive into why keeping your sleep debt low and syncing up with your circadian rhythm are some of the best exercises you can do to burn belly fat, and you don’t need to move a muscle to do them.
Belly fat isn’t solely caused by bad sleep, of course. An unhealthy diet, lack of exercise, stress, and other unhealthy lifestyle factors, like alcohol and smoking, play a role. But sleep is the one that’s often overlooked.
Several studies show sleep duration is integral to weight management. One study found those sleeping five hours or less a night had a larger body mass index (BMI) and waist circumference than those who slept for seven or more hours a night. The researchers concluded short sleep duration was significantly associated with an increase in general and abdominal obesity.
Sleep deprivation can also lead to insulin resistance, which can trigger the body into storing more fat around the midsection. Plus, lack of sleep can increase cortisol levels, which can also trigger more fat storage around the belly.
More research shows habitual short sleepers — defined as regularly sleeping for six hours or less a night — tend to have higher BMIs, fat percentages, and abdominal circumferences compared to average-duration sleepers — defined as sleeping seven to eight hours a night.
In fact, after analyzing several sleep studies, the researchers concluded:
“In addition to other health promotion measures, a good night’s sleep should be seen as a critical health component by clinicians in the prevention and treatment of obesity and type 2 diabetes.”
It’s not just habitual short sleepers, though. A 2022 study had participants sleep for four hours a night for 14 nights. Compared to getting nine hours of sleep a night, sleeping for this short a time caused them to eat more calories, without burning any extra calories. What’s more, they gained body weight in general as well as both subcutaneous and visceral abdominal fat.
Subcutaneous fat is the fat that sits just under the skin that we can see. Visceral fat, on the other hand, sits deep within the belly area around organs like the liver and intestines. This is the dangerous type of fat that’s been associated with high blood pressure, high cholesterol, insulin resistance, type 2 diabetes, stroke, heart disease, and certain types of cancer.
It’s not all about sleep duration, either. Research shows low sleep efficiency — the measure of how long you spend in bed actually sleeping — is associated with obesity and abdominal obesity. Having low sleep efficiency means it takes you a long time to fall asleep or you wake up often in the night.
Disturbed sleep has also been linked with glucose intolerance and insulin resistance, which are predictors of type 2 diabetes and can lead to more body fat storage.
One of the things that causes you to eat more calories when you’re sleep deprived is your hunger hormones being thrown out of whack. Not getting enough sleep leads to an increase in ghrelin — the hormone that makes you hungry — and a decrease in leptin — the hormone that stops you feeling hungry.
When you’re tired, your self-control takes a hit, too, meaning you’re much more likely to reach for processed, high-carbohydrate foods, instead of healthy snacks. Levels of certain endocannabinoids increase when you don’t get enough sleep. These signal to the brain’s pleasure receptors, making eating feel more enjoyable and increasing your cravings. Plus, when you’re low on energy, you’re much less likely to want to get your heart rate up and tend to skip exercise altogether, meaning those extra calories aren’t burned.
Pro tip: Getting enough sleep each night looks different for everyone. We all have an individual sleep need — the amount of sleep we need to be our best — that’s determined by genetics, just like our height and eye color.
While the average sleep need is 8 hours 10 minutes, plus or minus 44 minutes or so, 13.5% may need 9 hours or more sleep a night. To find out your sleep need, turn to the RISE app, which uses your phone use behavior and proprietary, sleep-science-based models to calculate exactly how much sleep you need.
The link between belly fat and sleep goes further than just how long you sleep for each night. When you sleep also makes a difference. This is where your circadian rhythm comes in.
Your circadian rhythm is your internal body clock that runs on a roughly 24-hour cycle. Research shows those who do things that disrupt their circadian rhythms — like work night shifts or sleep and eat at irregular times — have a higher risk for general obesity and abdominal obesity.
Sleeping and eating out of sync with your body clock throws everything out of whack. One study found those who slept and ate about 12 hours out of sync — which happens if you work night shifts — had 17% decreased leptin, 6% increased glucose, and 22% increased insulin. Being this out of sync also reduced sleep efficiency by 20%, which as we’ve shown is associated with abdominal obesity itself.
You don’t need to be 12 hours out of sync to see adverse effects, though. Social jetlag is when your social clock is out of sync with your biological clock. This might happen when you enjoy a later bedtime on the weekend than you do in the week. But research shows those with social jetlag have higher BMIs, more fat mass, and were more likely to be obese, even when taking into account sleep duration.
Even relatively small amounts of social jetlag can make a difference. Those with one to two hours of social jetlag have been shown to have 1.29 the prevalence of metabolic syndrome — which includes obesity, diabetes, and high blood pressure — than those with less than one hour of social jetlag. When that goes up to two hours of social jetlag — something many of us get on the average weekend — the prevalence rate is 2.13.
Now we’ve shown you how sleep and your circadian rhythm can impact body fat, and belly fat specifically, it’s time to talk about losing it.
You can’t “spot reduce” belly fat. That means while ab workouts like side planks, mountain climbers, and sit-ups can help tone up your abdominal muscles, they won’t specifically make you lose stomach fat. And sure, aerobic exercise and strength training will help you lose fat and belly fat, but you can’t forget about sleep.
While it’s not an exercise, sleep is an integral part of weight management and fat loss. And if you’re looking for activities to do to help you lose belly fat naturally, sleeping right should be at the top of your list. Plus, if you’ve been eating right and exercising, and you’re finding you can’t lose weight, your sleep may be the culprit. Here’s what to do.
Once you know your sleep need, aim to get that amount of sleep each night. Research shows even getting an extra hour of sleep or two — going from sleeping six or less to seven or eight hours a night — would result in 1 square inch less visceral fat gain.
But meeting your sleep need every single night isn’t always necessary. This is where you should consider your sleep debt. Sleep debt is the amount of sleep you owe your body over the last 14 nights. It’s measured against your sleep need, so if you need 8 hours 30 minutes sleep a night, but you’ve only been getting seven hours, you’ll have quite a lot of sleep debt.
First, you need to know how much sleep debt you’re dealing with. The RISE app works out how much you’re carrying. We recommend keeping this number below five hours to feel and function your best each day, and to help with your weight loss journey. If you find you’ve got more than five hours of sleep debt, you can catch up on sleep and reverse the damage.
You can reduce sleep debt by:
As we’ve shown, it’s not all about sleep duration. While you can lose belly fat overnight — by meeting your sleep need — you want to be sleeping at the right times for your body, too. The RISE app predicts your circadian rhythm each day so you can see when your body naturally wants to be awake and asleep.
To keep things aligned, you should:
Exercise is important for weight loss, of course. It can help you burn fat as well as build muscle. But if you’re trying to shift belly fat, exercises for your core muscles, full-body workouts, and even working with a personal trainer will be wasted if you don’t get your sleep right.
By keeping your sleep debt low and syncing up with your circadian rhythm, you can not only reduce the chances of poor-sleep-induced weight gain, but you can make losing belly fat easier to do too.
Turn to RISE to help. The app works out how much sleep debt you have and keeps track of it as you pay it back and it predicts your circadian rhythm each day to help sync up. Plus, RISE tells you the best time to do 20+ sleep hygiene habits to help you get the sleep you need each night to help you lose belly fat each day.
One home workout you can do to help you lose belly fat is sleep. Keep your sleep debt low and sync up with your circadian rhythm to help you lose belly fat and prevent additional weight gain.
To lose tummy fat fast, you should eat a balanced diet, exercise, and focus on your sleep. Keeping your sleep debt low and syncing up with your circadian rhythm can help prevent future weight gain and make losing current belly fat easier.
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