Sleep deprivation can do far more than make us grumpy and groggy. Inadequate rest — deemed less than 7 hours per night for adults — has been linked to adverse health outcomes ranging from depression to obesity. Sleep can be impacted by many elements, including: stress, illness, gender, hormones, age, shift work and lifestyle factors. According to the Centers for Disease Control and Prevention (CDC), ~35% of American adults aren’t getting enough sleep on a regular basis, 70 million suffer from sleep deprivation and around 40% are considered obese. So, is there a connection between sleep and weight loss? The short answer is yes. However, most people looking to manage their weight tend to focus on the traditional measures of eating less and moving more and don’t consider the power of sleep as a key factor for successful weight loss. 

How does sleep affect metabolism?

Sleep is controlled by circadian rhythms that tell your body when to rest and modulate many other physiological processes. When you are sleep-deprived, the circadian rhythm is interrupted; not only do you feel groggy, but your metabolism is also a tad on the dazed and confused side. 

Metabolism encompasses all the biochemical processes that occur within a living organism: essentially, converting what we consume into the energy needed to survive. When we are active, metabolic rate increases; but when we sleep, it slows down by about 15% — allowing an opportunity for restoration. When sleep is deficient and circadian rhythm is disrupted, metabolic dysregulation occurs and has been linked to weight gain. Although the physiological link is complicated and multifactorial, research suggests that the three main metabolic consequences connecting weight gain to lack of sleep include:  

• Altered glucose regulation: As mentioned in the article, Why Sleep Matters For Your Metabolic Health, research has found a link between lack of sleep and insulin resistance — putting people who are sleep-deprived at greater risk for glucose intolerance and type 2 diabetes.
  
  
• Lower levels of energy expenditure: Although a direct link between sleep loss and total energy expenditure has not been well-established, those with fatigue resulting from insufficient sleep report reduced physical activity and lower energy.
  
  
• Dysregulation of appetite: Restriction of sleep not only results in more time to eat, but causes an upregulation of appetite hormones.

Sleep and weight loss: How does sleep affect appetite?

If you are short on sleep and you find yourself experiencing the junk-food munchies, you are not alone. The more you are awake, the more opportunity there is to over-consume food — as documented in a review linking lack of sleep to increased snacking and number of meals consumed per day. Additionally, cravings for foods that tend to be higher in calories and carbohydrates have been clinically reported in individuals experiencing sleep deprivation. 

On a metabolic level, sleep deprivation can lead to an imbalance of appetite control hormones, fueling the desire to eat. Ghrelin is a neurotransmitter hormone that stimulates appetite by signaling your brain that you are hungry and prompting you to eat. Conversely, leptin suppresses hunger and signals the brain you are full. This balancing act is all good and well if you are getting your 7-hours of sleep, but when sleep deprivation sets in, the body responds by making more ghrelin and less leptin — which can lead to overeating. 

Helping to fuel the connection between sleep and weight, a 2022 study of chronically sleep-deprived adults found that sufficient rest at night reduced the amount of food eaten during the day by almost 300 calories. Putting those study results into perspective, if a reduced calorie intake were to be maintained over a three-year period, it would amount to a weight loss of ~25-pounds — just by getting enough sleep. 

How do sleep apnea and obesity factor in?

Sleep apnea can lead to sleep deprivation, which as we just discussed throws your metabolism off-kilter. According to the American Sleep Apnea Association, sleep apnea occurs in ~3% of normal weight individuals and over 20% of those who are considered obese. Sleep apnea occurs when the throat muscles relax and block your airway during sleep, causing you to stop and start breathing. In obese patients, weight loss has been clinically shown to play a role in alleviating symptoms and decreasing severity of sleep apnea. On the flip side, there is also evidence that treating sleep apnea decreases obesity. 

What is sleep hygiene?

In addition to the alarmingly high percentage of Americans who suffer from untreated sleep apnea, many of us are sleep-deprived even without such an anatomical cause —and so we, too, are at risk for the related adverse outcomes of weight gain, metabolic disorders and other chronic diseases, mental illnesses, decreased work productivity and family relationship difficulties. Stress is but one of many “environmental factors” that can affect the quantity and quality of your sleep … and yet there are strategies and practices you can employ to better manage these factors. Enter what is referred to as sleep hygiene.

Sleep is a biological necessity, but optimal sleep is what might be considered a learned behavior. Sleep hygiene involves paying close attention to factors such as a disruption-free bedroom environment and daily routines that promote consistent, uninterrupted sleep. The basics needed to improve your slumber are simple:

• Create a sleep-inducing bedroom environment
• Optimize and take control of your sleep schedule
• Craft a bedtime routine
• Foster pro-sleep habits during the daytime

Taking specific actions for each of the above can make it easier to fall asleep, stay asleep, and wake up well-rested, ultimately making weight loss more attainable. Learn more in How To Sleep When Stressed And Anxious and How Does Blue Light Affect Your Sleep?

Key takeaways

Although not a panacea for weight loss, getting adequate sleep clearly impacts the numbers on the scale. We’ve established that sleep deprivation impacts appetite and feelings of hunger and that lack of sleep can wreak havoc on metabolism. The standard recommendations of a healthy diet and regular physical activity are important pieces of the weight loss puzzle, but an understanding of the relationship between sleep and weight loss could be a pivotal factor in reducing obesity rates and the development of more effective weight-loss programs. Talk to your medical provider if you (or a loved one witnessing your sleep patterns) think that on an all-too-frequent basis you’re not sleeping well or for the recommended 7-hour duration; it could be a sign of sleep apnea, untreated anxiety or other ailments that could be medically addressed. Or, if the causes are within your control, learning more about sleep hygiene and the ways to improve it (everything from just dimming the lights two hours before bedtime to more involved practices such as taking up meditation or yoga) can go a long way to ensuring that your metabolic and overall health is maximized by more consistent and higher-quality sleep.