Sleeping Late At Night Associated with Obesity and Big Bellies

Published on June 12, 2024
Sleeping Late At Night Associated with Obesity and Big Bellies

When people notice their weight creeping up, they often blame their snacks or lack of gym visits first. Yep, snacking on carrots and skipping rope sure helps to stay in shape. However, get ready for a surprise: getting enough sleep is actually a big deal in controlling weight (1).

As important as a balanced diet and regular exercise are in weight loss, so is getting adequate restful sleep. Even if we don’t realize it, sleep deprivation can significantly influence our health and weight. But it has been proven beyond a reasonable doubt that lack of sleep is a risk factor for weight gain and obesity (1).

A lack of sleep affects all of us, and we can all relate to the tiredness that results from a poor night’s sleep. As a result, even the most well-intentioned intentions often fall by the wayside the next day (1).

As a result of not getting enough sleep, our desire to work out and complete tasks reduces dramatically. Regarding eating, we tend to choose unhealthy options rather than more nutritious ones. What about not getting enough sleep encourages us to prefer a slice of cake over a salad (1)?

As part of our research for this article, we looked into the connection between sleep duration and body weight. The underlying scientific concepts that govern these biological processes have also been examined (1).

Less Sleep Equals More Weight Gain

Much research has been done on the link between sleep and weight gain. According to the findings, we’re more likely to gain weight if we don’t get enough sleep (2).

They observed the following behaviors in a recent clinical experiment in participants who had been denied sleep:

  • They consumed a great deal more energy through their food.
  • They favored fatty foods more than other kinds of food.
  • Their rate of energy use remained the same.

Participants’ daily caloric intake increased by about 300 calories when they were sleep-deprived. The majority of these additional calories came from lipids.

They found that even one night of inadequate sleep resulted in people eating an additional 385 calories the following day in another study, which gathered data from over 170 participants who were submitted to partial sleep deprivation (2).

Sleep deprivation has increased the calories a person consumes, although this does not affect overall energy expenditure. The weight increase is inevitable when this pattern is followed for several days. With as little as 200 extra calories a day, it is possible to gain considerable weight (2).

For context, if you put a pound of fat in perspective, it has 3,500 calories. If you follow the same eating habits as someone who is sleep-deprived, you could acquire a pound of weight in as little as ten days. Over 2.7 kilograms (almost four pounds) of weight growth per year (2)!

As a result, the order in which we eat is equally critical. Weight gain was also more common in people labeled “night owls,” people whose activity levels peak later in the day and who often go to bed considerably later than the average person. As the day wears on, so does their level of activity. Late-sleepers eat about 250 more calories per day than persons who sleep “normally.” Due to this trend, they ate more fast food and fewer fresh fruits and vegetables (2).

Why is It That When We Are Exhausted, We Crave Foods High in Calories?

This may be a feature that has been preserved since the beginning of our evolution.

Cave dwellers who didn’t get enough sleep would have needed the extra energy to watch for potential dangers. Our modern civilization, where calorie-dense food is readily available and dangerous animals are less common, has made this habit counterproductive (3).

There are still many unanswered questions about how sleep and weight gain are linked. However, a growing body of evidence shows that not getting enough sleep alters our bodies’ biological processes, our brains’ functioning, and our behavior in daily life (3). 

When people are deprived of sleep, their daily caloric intake increased by an average of 300, and most of these additional calories came from fats.

Another study compiled data from more than 170 participants subjected to partial sleep deprivation. The findings showed that even just one night of inadequate sleep caused subjects to consume an average of 385 additional calories the following day (3).

However, even though the subjects consumed more calories while sleep-deprived, they did not increase their overall energy expenditure. When this routine is maintained for several days in a row, the end outcome is a gain in weight. Putting on significant extra weight might be accomplished with as few as 200 additional calories daily (3).

To put this into perspective, one pound of fat has the same calories as 3,500 calories. If you eat in the same manner as someone who is sleep-deprived, you could gain one pound of weight in fewer than ten days if you are sleep-deprived and make the same eating choices. That’s a possible weight gain of over 2.7 kilograms (almost four pounds) per year (3)!

It indicates that the timing of our meals is also essential. Another study suggested that persons considered “night owls,” whose activity levels peak later in the day and who go to bed much later than other people also had a higher risk of gaining weight (3). 

This is because their activity levels peak later in the day. It was shown that those who sleep late consume roughly 250 more calories than people who sleep “normally.” In addition, they ate more fast food and fewer fresh fruits and vegetables (3).

It’s likely a trait stored away throughout our evolution’s early stages. It’s possible that a caveman who didn’t get enough sleep required the additional energy to stay alert to potential threats. However, in modern society, when calorie-dense food is readily available, but dangerous animals are not as common, this behavior is now working against us (3).

There is still many mystery around the particular mechanisms that influence sleep and weight growth. However, many data illustrates how not getting enough sleep can change the biochemical processes in our bodies, how our brains operate, and how we behave in our day-to-day lives. When we take into consideration all of these different aspects, we find that in the:

  • All three of these impacts are interconnected, but it is simpler to notice their differences when they are grouped into these three distinct categories. 
  • Chemical messages are transmitted to the brain from the body. These messages are processed by our brain, which causes us to react in particular ways.

Now that we’ve covered the basics let’s get into the nitty-gritty of how not getting enough sleep impacts our bodies and minds and how the connection between those two factors can wreak havoc on our weight (3).

Hormones and Groans: The Reasons Why Fatigue Sends the Incorrect Signals

Hormones are chemical substances that perform the role of messengers, relaying information from one area of our body to another. When we don’t get enough sleep, many of our hormones become imbalanced, and some of these hormones are directly implicated in the process by which we put on extra weight (4).

It is recognized that these two hormones play a significant role in regulating our desire to consume food. These two hormones are called ghrelin and leptin. They have actions nearly opposite to one another: ghrelin causes us to feel hungry, whereas leptin is primarily responsible for giving us the sensation that we are full. Ghrelin is the hormone that tells us it’s time to eat, and leptin is the hormone that informs us when we’ve had enough (4).


Leptin is mainly produced by fat cells in the body. Its primary function is to control hunger, which allows it to regulate fat levels effectively. The amount of fat stored in the body strongly correlates with the quantity of leptin secreted. More fat equals more leptin (4).

The levels of the hormone leptin rise in a healthy individual who is carrying excess fat, and this sends a signal to the brain to limit appetite in response. The quantities of fat accumulated in the body can be reduced as a result of the body’s ability to use some of its fat reserves as a source of energy (4).

When we get enough sleep, our leptin levels should gradually rise at night, reaching a peak at about two in the morning. It’s possible that our body temperature gradually increases throughout the night to prevent us from feeling hungry when we should be sleeping (4).

According to the findings of several research that investigated the relationship between leptin levels and the amount of time spent sleeping, it appears that leptin levels are lower in those who are sleep deprived (4).

The levels of leptin in our bodies stay abnormally low when we don’t get enough sleep. The brain is under the impression that the body requires an increased energy supply (4).

After that, the brain will start sending hunger signals, eventually leading to us eating even though we don’t require the extra energy. Because the body believes that it needs to prepare for emergencies, it stores any calories that it takes in as fat (4).


The term “hunger hormone” refers to ghrelin, primarily produced in the stomach. This is because ghrelin is the hormone responsible for making us feel hungry (4).

The hormone ghrelin levels in the blood rise just before we eat, and it is believed that this causes the pangs of hunger that cause us to eat. After we’ve eaten, the amount of ghrelin in our bodies begins to fall (4).

Because the foods we eat affect our levels of the hormone ghrelin, and because carbohydrates and proteins cause a higher decrease in ghrelin than fats, choosing foods that are better for you may leave you feeling fuller than choosing, for instance, a burger from a fast-food restaurant (4).

Because our bodies don’t have as much of a need to burn as many calories when we’re not active, our levels of the hormone ghrelin naturally decline when we sleep. But our ghrelin levels do not drop as much as they should when we don’t get enough sleep. Even when there is no requirement for additional calories, one may experience feelings of hunger (4).

Sleep deprivation, therefore, makes us feel both hungrier and less full than we are. This occurs because it affects the levels of two essential hormones. It is not difficult to understand how this circumstance might, and undoubtedly will, result in weight gain (4).

Sleep and Diabetes

Insulin is another crucial hormone known to be altered when an individual does not get enough sleep. When our bodies become resistant to the effects of insulin, we are diagnosed with type 2 diabetes. When we think of insulin, we almost always concentrate on the vital part it plays in controlling the amount of sugar in our blood. Less often recognized is that it plays a crucial role in regulating the amount of fat our bodies store (4).

The release of insulin is the signal that signals our cells to take in sugar, which they subsequently use for energy. Our cells then use this sugar that they have taken in. However, it is also the signal for cells to begin producing fat for our bodies to store. Thus it has a dual purpose. When there is a higher level of insulin in the body, there is an increase in the amount of fat that is stored (4).

Studies have indicated that those who don’t get enough sleep have fat cells that are less responsive to insulin after it has been released. Insulin resistance is the first step in developing type 2 diabetes and is the term used to describe this condition (4).

These three hormones, leptin, ghrelin, and insulin (along with a few others that aren’t listed here), send the message to our bodies that we need to store fat when we aren’t getting enough sleep. While our systems are working to ensure that we have the energy to survive in our current condition of sleep deprivation, the end outcome may be increased body mass (4).

But that’s not the end of the excitement! How our brains operate while we are sleep-deprived is another factor contributing to this combination of sleep deprivation and weight gain (4).

There’s a party atmosphere up here, and sleep and the brain are both participating.

There’s a party atmosphere up here, and sleep and the brain are both participating.

There has been many research done on what occurs in the brain during sleep deprivation, and it is common knowledge that not getting enough sleep can significantly impact how our brains perform their functions. In a word, we lose control of our impulses and develop an insatiable need for pleasurable experiences. The next step is to investigate why (5).

In several studies, brain scans are used to examine how the brain reacts to certain foods or sights when it hasn’t had enough sleep versus how it reacts when it has had enough sleep. These investigations can provide us with precise knowledge regarding the processes that occur in particular brain regions when an individual is deprived of sleep (5).

Sleep deprivation has been demonstrated to affect two essential brain regions, according to imaging scans of the brain, which has been shown to impact weight growth. The amygdala and the prefrontal cortex are two parts of the brain (5).

The prefrontal cortex is highly vulnerable to sleep loss and is essential for several functions, including the following:

  • attention-span
  • decision-making
  • memory
  • problem-solving
  • self-control (amongst many other functions).

When we don’t get enough sleep, there is less activity in this brain region. As a result, we are less capable of making difficult decisions, exhibiting self-control, and having strong willpower (5).

Effects of Sleep Deprivation on Mood

In one brain imaging study, participants were divided into two groups: those who had a regular amount of sleep and those who had been sleep-deprived. From the beginning of one day to the end of the next, no sleep was permitted in the latter (just under 32 hours without sleep) (5).

In the following step, both groups were instructed to look at images and judge them as either pleasant or neutral, while MRI scans monitored their brain activity.

According to the results, subjects who had been sleep-deprived were much more likely to assess the photographs as agreeable than subjects who had been well-rested. When they studied their brain activity, it was found that their pleasure and reward centers were more active (5).

What precisely does this mean? An area of the brain called the amygdala, which is involved in regulating emotions and emotional behavior, is more responsive to pleasurable experiences (such as lying on a sofa watching TV) and rewarding ones (such as eating sweets) when we are sleep-deprived (5).

Our brain’s reward system uses the prefrontal cortex and amygdala to direct our behavior toward things we enjoy (like food, drink, and enjoyable hobbies) while steering us away from unpleasant experiences (like pain, conflict, and tasks we’d rather avoid) (5).

The good news?

Sleep deprivation can hurt our bodies capacity to regulate weight, but it’s not all bad news. Researchers are beginning to show that we can reverse these effects by increasing the quality and quantity of our sleep (5).

For instance, one positive study has revealed that we consume considerably less sugar when we get enough sleep. People went about their daily routines as usual. A second group was given tips and assistance on how to extend their time in bedtime naps (5).

The value of a good night’s sleep cannot be overstated. In addition to better weight control, you can see that taking steps to improve your sleep will also help you obtain a better night’s rest. Talk to sleep experts if you’re having trouble sleeping. They’ll work with you to figure out what’s causing your sleep issues and find a solution (5).

People who struggle with weight gain may be shocked to learn that addressing their sleep issues might help them acquire better control over their eating habits, willpower, and weight (5).


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