It is evident that being overweight or obese can have a negative impact on your health. Excess body fat is correlated with high blood pressure, heart disease, respiration problems, stroke, diabetes, and many more medical conditions. While it is clear how diet and exercise impact body weight, we are particularly interested in the connection between body mass and sleeping patterns.
There is a rise in obesity and sleep problems in the world, and it didn’t take us long to make a connection between those two. This rise is mostly attributed to less exercise and eating more unhealthy food.
The interactions in our body are quite complex, and while a lack of sleep can lead to gaining weight, being overweight also leads to disruptions in your sleep. Excess weight can lead to snoring and sleep apnea, and obesity is linked with increased chances of developing restless legs syndrome. Poor sleep leads to changes in your metabolism, hormone expression and it also affects parts of your brain, making you more hungry and less satisfied after a meal.
The Risks Based on Your Body Weight
Body mass index (BMI) is often used to estimate your relative body fat based on your height and weight. While it is not a completely precise system, it can give you an idea if you should pay more attention to your weight. There is a number of online calculators that you can use to identify your BMI, and then find out where you stand.
- Underweight (BMI <19)
- Healthy weight (BMI 19-24.9)
- Overweight (BMI 25-29.9)
- Obese (BMI 30-34.9)
- Morbidly obese (BMI over 35)
The results are based on the average body construction, so they can be off for athletes who have more muscles, or older people that have lost muscles on account of body fat.
You don’t have to worry if you are a few pounds overweight, as it might not have a negative impact. However, the more you weight, the more likely you are to get one of the medical conditions linked to excess body fat.
Impact of Sleep Deprivation on Hormones Responsible for Weight Gain
Sleep deprivation negatively impacts your body’s ability to use insulin. Insulin is crucial for removing glucose from the bloodstream and bringing them to cells that later use these molecules to get the energy they need to function correctly. Insulin resistance is linked to sleep deficit, and when our body is less sensitive to insulin, it produces more of it. That leads to storing fat in the wrong places, like your liver, and that is exactly how you become obese and more prone to suffer from a disease like diabetes.
The interactions between the two hormones, leptin and ghrelin, control hunger. Ghrelin is a peptide produced by the stomach, and its primary role is to stimulate appetite. The levels of ghrelin are high before the meal, and then they drop afterward. Ghrelin also has a long-term effect on body weight regulation, and its levels are usually higher in obese people. Ghrelin also promotes lower metabolism and increased storage of fat. The other hormone responsible for hunger is leptin. It is produced by fat cells (adipocytes), and increased levels of leptin is a signal that you are full. Decreased leptin levels stimulate hunger, so it is pretty clear how these two hormones work together to signal your brain that it is time to eat.
Sleep loss makes your daily leptin levels drop, while it increases ghrelin, making it nearly impossible to lose weight. In addition to that, sleep deprivation also increases the levels of cortisol, a stress hormone that among many other functions, controls how your body uses different nutrients. It is associated with fat gain and activation of reward centers that makes you want more food. Increased levels of ghrelin and cortisol turn off the parts of your brain that indicate satiety, so you’re going to feel hungry all the time, even if you just had a lunch that should be satisfying.
To make things even worse, sleep deprivation impairs the activity of your frontal lobe, an area in charge of complex decision making. When you are over-tired, the activity of your amygdala is increased as well. That makes you want to eat high-calorie food more. And since your decision making is disturbed by the lack of sleep, you are more prone to give in to those urges and forget about eating healthy.
Orexin or hypocretin is a hormone responsible for keeping us awake, and it also plays a role in appetite cycle. The interactions between orexin and other hormones are yet to be researched, but it just shows how complicated our bodies are, and how hard our brain is working to keep everything in place.
Evolutionary Explanations for Links Between Sleep and Body Weight
Large meals make you sleep, which makes a lot of sense evolutionary since our ancestors were always in the search for food. When they were full, it meant that they had time to sleep. Sleep conserves energy and also gives the body time to repair and grow. Growth hormone is released during deep sleep, so it is essential that children get sufficient sleep. Hunger, on the opposite, can prevent rest, and our ancestors had to make sure they found food before going to sleep.
A potential evolutionary explanation to the relationship between weight gain and sleep may be explained by the availability of food-induced by seasonal changes in daylight. Our ancestors ate more during the summer when there was plenty of food, and they also slept less because of the shorter nights. During the winter, there was less food available, so they had to sleep longer to conserve energy better. Now, we had plenty of food available all year long. But when we get less sleep, our brain can still perceive it as a season when we eat more, and that’s why we gain weight.
Sleeping Conditions Caused by Excess Body Weight
Gaining weight can lead to snoring, sleep apnea, hypoventilation, and restless legs syndrome. Extra weight can lead to larger neck size, and also to a reduced lung volume due to the increased stomach. This can cause problems and collapse the airway.
Snoring is often the first sign that something is off with your sleep. Snoring is merely disturbed airflow, but it can lead to more damaging conditions. Storing extra fat in the tissue around your airway often leads to snoring. Other obstacles can induce snoring, such as enlarged tonsils and adenoids, a smaller lower jaw (retrognathia), a deviated septum in the nose, or large tongue (macroglossia). Children particularly have problems with enlarged tonsils.
Sleep apnea is a condition of blocked airways that lead to nightly pauses in respiration. When the airflow completely stops, it is called apnea, while partial cease of airflow is called hypopnea. The symptoms of sleep apnea are fatigue, excessive daytime sleepiness, impaired memory, concentration, and mood. Sleep apnea can lead to more severe consequences. It can increase the risk of heart failure, hypertension (increased blood pressure) and diabetes. It’s also correlated with a higher risk of a stroke and sudden death. If you are experiencing any of the mentioned symptoms and suspect that you are suffering from sleep apnea, pay a visit to your doctor. They’ll refer you to a sleep specialist who will run a series of test and give you a diagnosis. If you are suffering from sleep apnea, don’t worry, continuous positive airway pressure (CPAP) therapy is highly effective.
Hypoventilation is another respiration-related condition that affects obese people. People usually exhale carbon dioxide, but being overweight can prevent that during the night. It can be so severe that some people can’t even catch up and get rid of all the carbon dioxide during the day. That can lead to a lot of cardiovascular problems as well as death.
Restless legs syndrome is a sleep disorder described by the strange sensation of discomfort in legs during the night. People who experience this often have an urge to move and relieve the pain. There could be many causes behind the restless legs syndrome including iron deficiency and pregnancy. Being obese is also one of the factors that highly increase the chances of obtaining this condition. The relationship between those two is not fully understood, but it is suspected that chemical messenger in the brain called dopamine is involved.
People with restless legs syndrome often find themselves grabbing a midnight snack. This is shown to relieve the symptoms temporarily but can lead to more weight gain.
Sleep-related eating disorder is a condition of abnormal sleep behavior or parasomnia. People affected by this disorder are repeatedly found eating during their sleep. This action is involuntary, and they can even consume inedible food. They often realize what happened after they found missing food or mess in the kitchen when they wake up in the morning.
While it is not shown that overweight people are more likely to suffer from this condition, it is evident that this disorder can lead to gaining weight.
Lack of Sleep and Exercising
Besides affecting your diet, sleep deprivation also has an impact on your exercise. Lack of sleep leads to more sleepiness and fatigue during the day, as well as less motivation to do things. That will make a hard task of going to the gym even harder.
Sleep also affects gym performance, and more rest means increased gains. Remember that during the deep stage of sleep, your body releases growth hormone that is important for your muscles. Sleep also lets your body restore properly after an exercise.
Lack of sleep means a higher production of cortisol, a stress-inducing hormone. More cortisol means less growth hormone, so it seems like a never-ending cycle.
More muscles mean more fat burning, so make that first step and start exercising. It will impact every aspect of your life. You’ll lose weight, improve your health and sleep, increase your circulation leading to better concentration and memory. With so many positive effects, there is no reason why you shouldn’t try being active.
Can Sleeping More Help You Lose Weight?
A large study was done at Case Western Reserve University, and it included more than 68,000 women. Women were all nurses, and first, they filled the questionnaires about their sleeping and other life habits, and their weight was measured. Over the next 16 years, researchers tracked how different parameters changed in relation to how much sleep each woman got during the night.
During those 16 years, 10.5% of women in this study experience weight gain of 15 kilograms. Nurses who slept for seven to eight hours on average had the lowest risk of 15-kilogram weight gain. Women who slept five hours or less were 32% more likely to experience 15kg weight gain, while those who slept 6 hours on average had 12% more chances of gaining 15 kilograms.
Other variables were included in the statistical analysis, and still, sleep time was the key factor to weight gain. Nurses who slept for less than seven hours were 15% more likely to suffer from obesity.
There are many more studies with similar results, including this study done in the Institute for Clinical and Experimental Medicine in Prague.
The Bottom Line
Sleep deprivation can lead to an increase in appetite and can impact your metabolism and the way your body responds to food. It also impairs your decision making and makes you crave high-calorie food while leaving you less satisfied after a meal.
Along with a healthy diet and exercise, healthy sleeping habits play a significant role in weight maintenance. If you are struggling to lose weight, it would be best for you to try and change all of these aspects of your life. That will lead to better and faster results.
Dusan is a biologist, a science enthusiast and a huge nature lover. He loves to keep up to date with all the new research and write accurate science-based articles. When he’s not writing or reading, you can find him in the kitchen, trying out new delicious recipes; out in the wild, enjoying the nature or sleeping in his bed.