A common midlife mystery women face during the menopause transition is, “I’m gaining weight, but I follow the same routines I always have and can’t figure out what’s changed. Is this perimenopause, my metabolism, or something else altogether?”
It’s impossible to answer that question without exploring individual lifestyle factors and health history, but during this period of hormonal shifts, physical and emotional stressors, life’s daily demands, and the natural effects of aging, it’s normal to notice some changes to how your body looks, feels, and functions.
The metabolism, or how our body converts nutrients from food into energy to keep physiological processes working properly, is a complex, sensitive system. It’s determined by our genes, age, hormones, body composition, and factors such as what we eat, how much we move during the day, certain medications, and how we sleep. Directly and indirectly, the quality of your sleep (and how much of it you get) can affect how your metabolism functions, and thus how your body burns calories and holds on to weight.
If you’re experiencing weight concerns during menopause that aren’t responding to diet and exercise in the way you’d expect, one thing to consider is the role sleep plays in metabolic function. Understanding this relationship can help make sense of what’s going on with your metabolism during midlife, which is often a time when regular, restorative sleep becomes more elusive, and we face new sources of stress.
Here are three major ways sleep affects metabolism:
1. Sleep patterns influence the hormones that regulate metabolism and appetite
We know it feels like you can’t catch a break from hormone swings during perimenopause, given all the effects of fluctuating and declining estrogen, progesterone, and testosterone. The truth is, all hormones fluctuate to some extent based on internal and external cues—it’s how your body runs essential processes like digestion, circulation, tissue repair, and more. So, while changing hormone levels aren’t necessarily abnormal or a bad thing, the ratios between them need to stay balanced so that they can cue your body to do what it needs to do. Interference from things like stress, dietary changes, and sleep deprivation can throw hormone levels out of balance and affect systems like your metabolism.
Some of the hormones involved in metabolism that are particularly sensitive to disrupted sleep are:
Cortisol – You may know cortisol as the “stress hormone,” and recognize it as the subject of many social media videos lately. And no wonder, since it does an awful lot in our bodies and having imbalanced levels can cause noticeable symptoms. While cortisol does play a big role in your body’s stress response, it has other functions too, like rising and falling throughout the day to cue your body to wake up and get drowsy during the sleep-wake cycle. As for its involvement in metabolism, cortisol works alongside other hormones, like insulin, to regulate blood sugar.
Most of the time, cortisol’s fluctuations are normal, natural, and necessary. However, sources of stress, like poor or insufficient sleep, can cause cortisol levels to stay elevated instead of following the ideal ebb and flow of their daily rhythms. Over time, this can interfere with how efficiently your metabolism works and result in:
- Elevated blood glucose: High cortisol triggers the release of glucose into the blood. At continued high levels, cortisol keeps signaling to the body to release more glucose, as though a tap has been left open. If the body can’t process the excess glucose and use it as energy, it converts it to abdominal fat instead.
- Increased fat storage and body composition changes: Persistently high cortisol levels can encourage the body to hold on to visceral fat surrounding the internal organs, especially around the abdominal area.
- Increased cravings for sweet, starchy comfort foods: Elevated cortisol, along with other hormones, is thought to increase cravings for highly palatable, high-calorie foods which, in excess, can contribute to weight gain.
Insulin – Insulin is a hormone that helps the body metabolize fat, protein, and carbohydrates. One of its main roles is to help different tissues absorb glucose from the bloodstream so it can be converted into energy—in other words, insulin’s a major player in regulating blood sugar.
Sleep loss, especially when it’s chronic, reduces the body's sensitivity to insulin, meaning cells in the muscles, liver, and body fat become less responsive to its signals. When that happens, glucose can build up in the bloodstream instead of being absorbed by our cells and turned into energy. Over time, this can lead to insulin resistance and contribute to metabolic disorders like Type 2 diabetes or metabolic syndrome in people who may already be at risk.
Ghrelin and Leptin – These two hormones regulate hunger and satiety (a sense of fullness and satisfaction after eating) and have important roles in managing the body's energy intake (eating and drinking) vs expenditure (burning calories). Ghrelin, made mostly in your stomach but also secreted by the brain, small intestine, and pancreas, is often called the “hunger hormone” because it stimulates the appetite.
Leptin, otherwise known as the “satiety hormone,” is produced by fat cells when your body recognizes that it has enough energy reserves. It suppresses hunger by telling your brain you’ve had enough of the right nutrients to replenish your energy.
Together, these hormones help your body prioritize which nutrient sources to use for fuel and sense when energy stores are low so you can fill them back up with a meal.
Like other hormones, ghrelin and leptin respond to inputs like physical activity, dietary habits, circadian rhythms, levels of other hormones, stress, and—you guessed it—sleep. Lack of sleep or poor-quality sleep can cause ghrelin levels to spike and leptin levels to drop; this can lead to increased cravings for calorie-dense foods for quick hits of energy and difficulty sensing fullness, making it easier to eat past satisfaction and consume more than your body needs.
2. Deep sleep is necessary for cellular recovery and repair that supports metabolic function
A good night’s sleep is more than just the amount of time you spend in bed—the sleep stages matter.
If we’re healthy and sleeping well (that is, not dealing with sleep disorders or interruptions during the night) we can expect to cycle through rapid-eye movement (REM) sleep and multiple stages of non-REM sleep several times a night. During these stages, our brain wave activity changes and follows different patterns; these cycles determine when we dream, organize memories and process information, or carry out cellular healing to restore tissues to optimal function and repair them after injury and inflammation.
The stage called deep sleep, also known as slow-wave sleep, helps us wake up feeling well-rested and is critical for cellular recovery. And properly functioning cells are essential for a properly functioning metabolism!
Lack of deep sleep, either because of trouble getting to that stage or from not spending enough time in it, can interfere with:
- Metabolic flexibility: Put simply, metabolic flexibility is the body’s ability to switch between fuel sources (glucose or fat) depending on its energy needs for a given activity. Good metabolic flexibility is a helpful indicator that your body is able to regulate blood sugar, burn fat as fuel instead of storing it, and balance energy intake and expenditure efficiently throughout the day.
- Muscle building and recovery: Metabolism isn’t just about breaking down nutrients from food—it's about putting them to work, too. During deep sleep, a healthy metabolism helps your muscles recover from inflammation or damage from illness or injury. It also helps build new muscle tissue. This is especially important during midlife, since muscle loss is common during both aging and menopause and is a big contributor to decline in metabolic rate.
- Cellular repair: Your muscles aren’t the only things that go through repair and restoration during deep sleep. All cells get this tune-up treatment overnight, including those involved in metabolism; without that recovery, functions like hormone modulation and blood sugar regulation can be impaired or remain imbalanced.
It's typical to get less deep sleep as we age, but the menopause transition can make it even harder to get the amount we need. This period of life is full of things that keep us awake, be they hot flashes and night sweats caused by declining estrogen; night awakenings due to hormone shifts; circadian rhythm disruptions; sleep disorders; stress and anxiety; or interruptions from kids, partners, or pets.
Gennev’s Chief Medical Officer Dr. Rebecca Dunsmoor-Su points out that prolonged lack of deep sleep can reduce the basal metabolic rate (how many calories we burn at rest), keep cortisol levels higher than they ought to be, and generate some insulin resistance, all of which can contribute to changes in what kind of body fat we accumulate and where we store it, particularly during menopause when the body is adjusting to a whole host of new conditions.
3. Sleep loss and fatigue can lead to behavioral changes that may influence metabolic health over time
Time for a judgement-free truth: The best-laid plans can often go awry when chronic sleep loss is involved. Poor sleep and fatigue affect energy levels, coordination abilities, emotions and mood regulation, memory and cognitive abilities, and appetite, so is it any surprise that we might not feel up to our ideal routines if we’re frequently not sleeping well?
Of course not! Tired minds and bodies want to save energy, not spend it, so it’s normal to choose less taxing activities when we’re not well-rested. Menopause can compound this, introducing levels of fatigue that can catch many women off guard and interfere with their quality of life.
The resulting cycle might sound like a familiar one: long stretches of poor sleep leave you perpetually exhausted while juggling a never-ending to-do list. For many, that makes it harder to consistently do things that support metabolic function and optimal sleep patterns, like prioritizing exercise or eating foods that provide plenty of complex carbs, protein, and healthy fats. That’s not a personal shortcoming, by the way—life asks a lot of us all, and today’s culture doesn’t always make it easy to nail sleep, nutrition, and physical activity the way we’re told we should.
In the long run, this cycle of fatigue from sleep loss, little exercise, and a diet that might offer quick calories without enough nourishment can take a toll on metabolic health as the body tries to keep all systems working efficiently. Without adequate fuel and recovery, it must make some adjustments to compensate, like holding on to body fat and lowering the basal metabolic rate to conserve energy (thus burning fewer calories), and has a harder time keeping hormones balanced and blood sugar stable. If these conditions continue for too long, it may increase the risk of more serious metabolic disorders and chronic disease associated with poor sleep.
Feel better, sleep better, and support your metabolism
Sleep and metabolism are incredibly complicated topics, and both aging and menopause can make them even more so. It can be difficult to say exactly what the culprit is for some of these complaints, but if you’re troubled by changes to your sleep, your body composition, or your energy levels, you don’t have to struggle through them alone.
Consider making an appointment with a menopause-trained Gennev physician or Registered Dietitian Nutritionist who can help you understand your metabolism, make sense of your symptoms, and find relief through personalized care plans.
If you or your doctor suspect you may have a sleep disorder due to symptoms that don’t respond to medications, hormones, behavioral or habit changes, you may want to be evaluated for sleep apnea. It’s a common sleep disorder that affects women more frequently after menopause and can be linked to other health conditions. You can’t diagnose yourself, but convenient at-home sleep studies are available through companies like Complete Sleep. If you do have sleep apnea, Complete Sleep also offers custom mouth guards, covered by insurance, for an easy-to-use treatment option that can support better, more restful sleep.
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