Several of our internal body systems can go awry without healthy sleep habits, which can affect how our body weight fluctuates. Our metabolic system is responsible for converting food into energy that our bodies can use. When our metabolic system is thrown off balance from a lack of sleep, it can impact both weight gain and loss.

Understanding the specific relationship between sleep and weight may help motivate and educate you on how to maintain both a healthy weight and healthy sleep habits.

Sleep deficiencies over a prolonged period can negatively affect a healthy metabolism,1 affecting weight through various biological pathways. In some instances, these pathways intersect and build on each other to affect weight gain even more. Keep reading to learn a few of the ways a lack of sleep can affect your metabolism.

How sleep affects the metabolism

  1. It helps keep your appetite in check.
  2. It helps manage stress.

  • 1. It helps keep your appetite in check.

    When you’re absolutely exhausted, you may find yourself craving junk food. That’s because when we don’t get enough sleep, two hormones that regulate our appetite are affected. The level of leptin, a hormone that makes us feel satisfied when we have had enough to eat, decreases.2 Lack of sleep also increases levels of ghrelin, also known as the “hunger hormone.” As a result of these hormonal changes, we may feel hungrier and compelled to eat more than we would if we were well-rested.2 3

  • 2. It helps manage stress.

    Without enough sleep, our bodies release more cortisol—often referred to as the “stress hormone”—into the blood stream.3 The elevated level of cortisol slows down the metabolism, impairing the body’s ability to convert sugar into energy, making it harder to lose weight.

Sleep and physical activity

Sleep deprivation causes tiredness, which may hinder physical activity, ultimately decreasing how many calories the body burns throughout the day. It makes sense—when we are tired from a lack of sleep, a 20-minute nap sounds more inviting than a 20-minute workout routine.

But the fatigue and exhaustion that accompany sleep deprivation aren’t the only reason sleep impacts physical activity. Sleep disturbances can also lead to physiological changes that more directly impact fitness level. Research on the effects of sleep deprivation suggest that sleep is very important for building muscle and using the fuel from our food to increase our strength.

When people experience just one night of sleep deprivation, they may display an impaired ability to build muscle6—or more specifically, the synthesis of skeletal muscle protein that our bodies normally undergo after we eat is significantly impaired.4 5

Does lack of sleep cause weight gain?

If you’re not getting enough sleep, your body is tired and trying to find fuel in different ways—affecting how you eat, what you eat, how your body builds muscle mass, and of course, how motivated you are to exercise. So, it’s no surprise that those with unhealthy sleep habits are more likely to gain weight than those with healthy sleep habits.

There is an abundance of research specifically showing that those who sleep too little or too much are at a higher risk of weight gain.2 3 6 7

How a lack of sleep can lead to weight gain

Sleep deprivation is shown to lead to weight gain even in those who do not eat more or exercise less.

Even when eating and exercise habits are maintained, research shows that a lack of sleep still increases the likelihood of weight gain.8 These findings suggest that sleep influences weight beyond its effect on diet and workout habits. So even if you can maintain a well-balanced diet and exercise routine without sleep—which would become almost impossible after a certain period of time—your lack of sleep can still cause weight gain.

The more sleep deprived people are, the more weight they gain.

Getting less than the recommended 7 to 9 hours of sleep each night for the average adult increases their risk of weight gain.8 9 10 The amount of weight gained, however, appears to depend on the extent of the sleep deprivation. One study showed that compared to people who sleep at least 7 hours per night, those who sleep only 6 hours per night gain more weight. Furthermore, compared to those who sleep 6 hours per night, those who sleep only 5 hours per night have been shown to gain even more weight.9

Can sleep and weight loss

Just as sleep deprivation can lead to weight gain through its effects on the physiology of our metabolism, our appetites, and our physical activity, it can also impair our ability to lose weight. However, while there is much more research on the tendency of sleep deprivation to lead to weight gain, there are also some studies that show that poor sleep hygiene makes it harder to lose weight.

For example, a multicomponent weight-loss program that included addressing sleep hygiene behaviors led to successful weight reduction, highlighting the importance of addressing sleep when working to lose weight.11

Sleep and weight are inextricably linked through their relationship to metabolism, eating, and exercise. Finding the right balance of nutrition, exercise, and sleep is the best way to promote healthy weight and to support your overall health.

The importance of good sleep hygiene

Establishing healthy sleep habits is essential to maintaining general health. Promoting a healthy lifestyle goes hand-in-hand with ensuring that you are not only getting enough sleep, but also getting quality sleep.

*These statements have not been evaluated by the U.S. Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.

References:

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  3. Cooper CB, Neufeld E v., Dolezal BA, Martin JL. Sleep deprivation and obesity in adults: a brief narrative review. BMJ Open Sport — Exercise Medicine. 2018;4(1):392. doi:10.1136/BMJSEM-2018-000392
  4. Prokopidis K, Dionyssiotis Y. Effects of sleep deprivation on sarcopenia and obesity: A narrative review of randomized controlled and crossover trials. J Frailty Sarcopenia Falls. 2021;6(2):50-56. Published 2021 Jun 1. doi:10.22540/JFSF-06-050
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