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This Is Your Metabolism on Sleep Deprivation 

Is the state of your sleep curtailing your weight loss? If so, you aren’t alone. The majority of Americans get less than 6 hours of sleep per night. Are you among them? Does 6 hours a night actually sound like a luxury? If so, the answer to your weight loss difficulties may not begin with changing your diet and exercise but may first require an appropriate bedtime and better quality rest. Research into the metabolic effects of sleep deprivation reveals some startling insights about the role of rest in metabolic functioning. Read on to see just how your metabolism is altered with even a few nights of insufficient or disrupted sleep.


How does your body process the carbohydrate (glucose) that you eat? Answer: a hormone called “insulin.” Failing to get adequate sleep for even a few nights has been found to significantly impact the body’s ability to manage its blood sugar levels. Insulin resistance occurs when higher amounts of insulin are needed to reduce blood sugar levels because the body is unable to use it as effectively. Being resistant to insulin causes glucose (blood sugar) to accumulate in the blood instead of being absorbed by cells for energy. This progressive resistance leads to numerous ailments such as prediabetes, type 2 diabetes, polycystic ovary syndrome, metabolic syndrome, and many more conditions.


Raise your hand if you’ve stayed up late and the next day gorged on all manner of poor food choices? There’s a significant correlation between sleep shortage and appetite. Recent studies have shown that our “appetite-regulating hormones,” ghrelin and leptin, are profoundly influenced by sleep duration - and the impact doesn’t just happen with long-term or dramatic sleep deprivation. Leptin is a hormone that signals satiety to our brains. It’s the “I feel full” message we get. Ghrelin, on the other hand, is known as the “hunger hormone” that signals our brains that we’re hungry. In numerous studies, sleep reduction was associated with leptin decrease and ghrelin elevation - a double whammy against any weight management or health goal! More ghrelin + less leptin = “I still feel hungry!” The resulting hunger cues are usually satisfied with poor food choices like carbohydrate-dense, sweet and salty foods. Reduce these unhealthy cravings and hormonal confusion by prioritizing “lights out” no later than 10:00 p.m.

Fat Loving

Not only does lack of sleep lead to increased risk of diabetes due to increased blood sugars, but what does excess sugar in the body also lead to? Weight gain! Our bodies can only process a certain amount of carbohydrate (glucose) at one time, and the rest is stored as fat. Therefore, ongoing insufficient sleep leads to more and more potential fat gain. In addition, when insulin levels are elevated, our bodies are unable to burn fat! Researchers have found significant differences in how fat tissue responds to insulin with as few as four nights of disrupted sleep. Besides the physiological response to store fat, let’s state the obvious. When you lack adequate sleep, your energy levels plummet. When your energy is low, one of the first things to fly out the window is movement and/or exercise.

Growth Deficient

Sleep is crucial for appropriate recovery and cell restoration. Many of us have felt these benefits especially after a challenging workout or productive day in the yard. A hormone that aids in this process is growth hormone (GH), which promotes the growth of muscles. It is anabolic to tissue in our bodies and catabolic to fat mass (a serious win-win!). Growth hormone is released during REM sleep, which occurs typically several times a night for people who obtain sufficient sleep. Each time we fall into REM sleep, a burst of GH is released, which allows the body to use it to build muscle AND burn fat. For those who get insufficient sleep and/or disrupted sleep (never achieving REM cycles), the GH hormone is never released, muscle mass isn’t built, and the body doesn’t burn fat as readily. In fact, more fat is stored! Furthermore, the timing of GH release is based on the body’s circadian rhythms, with more being released earlier in the night in comparison to the later hours. A sleep schedule from 10 p.m.- 6 a.m. (8 hours) actually results in more GH than the same 8-hour duration from 12 a.m.- 8 a.m. Not only does sub-optimal sleep disrupt the amount of GH released, but so does insulin. When insulin is present, it inhibits the secretion of growth hormone and results in minimal GH release. What does that mean for you? More insulin = less growth hormone, which (in turn) means less muscle gain and less fat burned.


Our bodies naturally respond to stress throughout the course of the day by increasing and decreasing cortisol (a steroid hormone that helps us respond to stressors). The natural level of cortisol during the day is highest in the morning and gradually tapers off throughout the day. By the time we’re getting ready for bed, we’re under minimal “stress,” and melatonin (our natural sleep hormone) can kick in to allow for restful sleep. In people who get adequate sleep, cortisol levels decrease at a steady rate. In studies when individuals got only 4 hours of sleep per night, evening cortisol levels were elevated and decreased 6 times slower when compared to the control subjects. This increase in cortisol actually leads to an increase in belly fat, which is very detrimental for overall health, given its association with inflammation and obesity, among other influences.

Are you seeing a pattern yet? When we deprive our bodies of the quantity and quality of sleep they need, we send ourselves into a revolving door of imbalanced and confused hormones. When our hormones are out of whack, we feel the repercussions in numerous, negative ways. Inadequate or disrupted sleep could very well be the most significant stumbling block between you and your weight loss or body composition goals. When you begin to improve your sleep habits (with good choices around other lifestyle factors like diet and exercise/movement), you will immediately begin to reap the physical and mental benefits. Likewise, the energy and hormonal balance that adequate sleep offers can help you commit to bigger health intentions and boost your overall weight loss progress.

How to Create a Better Sleep Routine:

  • Avoid caffeine in the afternoon. Caffeine’s half-life is about 7 hours, which means even though you may not feel that afternoon coffee when you go to bed, it’s actually still operating in your system.
  • Minimize screen time, especially in the hour or two prior to bed.
  • Limit processed foods and overconsumption of refined carbohydrates (e.g. high-sugar foods). Instead, focus on meeting your quota of fibrous vegetables, adequate protein, and healthy fats.
  • Get moving! Increasing your movement throughout the day will help you manage stress and cultivate hormonal balance - two achievements that can allow you to rest more easily - literally and figuratively - each night. 
How much sleep do you get each night? Do you feel sleep quantiity or quality has influenced your weight loss or health? Share your questions and strategies, and thanks for reading!


Written by Becca Hurt, MS, RD, Program Manager of Life Time WeightLoss

This article is not intended for the treatment or prevention of disease, nor as a substitute for medical treatment, nor as an alternative to medical advice. Use of recommendations in this and other articles is at the choice and risk of the reader.


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