[Written in partnership with RENN Asia Wellness, but the editorial team had full control over the content.]
It’s no secret that good sleep is important.
But in addition to boosting mental clarity and improving mood, quality sleep actually significantly impacts how the body metabolises energy.
Yes, that means that poor sleep can lead to weight gain or an inability to lose weight.
We turned to Jonathan Chew, the founder of RENN Asia Wellness, to shed more light on all our questions on sleep and its link to our metabolic health.
But is sleep really the issue?
Apparently, the answer is often yes. Very often, in fact.
“In my experience, what looks like a lack of motivation is frequently underpinned by poor sleep, whether quantity, quality, or disrupted circadian rhythm,” Jonathan explained.
“When someone tells me they just don’t have the energy to exercise or stay focused or just generally fatigued, sleep is one of the first areas I investigate. Or rather, asking about sleep is a ‘must’ question to ask everyone.”
But is sleep the root cause, or just a symptom? Well, Jonathan says that depending on the case, it can be both.
To elaborate, sometimes poor sleep is a symptom of blood sugar instability, nutrient imbalances, or hormonal shifts. But other times, it is the root cause, especially when it leads to elevated cortisol, impaired insulin sensitivity, or inflammation.
“So in my wellness programmes, sleep is always a priority pillar—not just a footnote,” Jonathan added.
But how is bad sleep bad?
We know that bad sleep can affect your energy levels, but how specifically does it affect issues involving your metabolism? Here’s the tea.
1. Disrupted sleep raises blood sugar levels
Poor sleep can increase blood sugar levels because lack of sleep impacts insulin sensitivity.
Insulin moves glucose (sugar) from the bloodstream into the cells, where it’s used for energy or stored in the liver. When sleep deprivation disrupts this process, the cells become less responsive to insulin.
As a result, glucose remains in the bloodstream longer than it should, causing blood sugar to spike.
The long-term effects of this can be severe, because impaired blood sugar control can increase the risk of developing diabetes.
Studies reveal that individuals who consistently get fewer than five hours of sleep per night are twice as likely to develop prediabetes compared to those who sleep seven hours.
2. Sleep deprivation boosts hunger and appetite
Poor sleep influences hunger hormones, notably leptin and ghrelin, which work together to regulate appetite. Poor sleep raises ghrelin (the hunger hormone) and suppresses leptin (satiety). It also dysregulates insulin.
If people wake up groggy and need sugar for energy, sleep is very likely part of the problem, not just the food itself.
Furthermore, research shows that people who get less sleep are prone to choosing foods high in calories and lower in nutrients.
“When someone complains of sugar cravings or can’t seem to lose fat despite dieting, I look at sleep duration and quality,” Jonathan mused.
3. Poor sleep increases stress hormones
It’s a cycle: Poor sleep can increase stress levels, while high stress can make it challenging to get restful sleep.
This vicious cycle significantly affects metabolic health, primarily because of the hormone cortisol, commonly known as the “stress hormone.” Cortisol follows a natural rhythm, peaking in the morning to help with wakefulness and dipping at night to promote relaxation.
When sleep is compromised, cortisol levels can remain high throughout the day. This increase in cortisol disrupts the sleep-wake cycle, impairs the body’s ability to burn fat, and encourages muscle breakdown.
What’s more, prolonged high cortisol levels have been linked to conditions like inflammation, high blood pressure, and osteoporosis, impacting metabolic health.
Reducing stress through sufficient sleep is vital in maintaining balanced cortisol levels and, in turn, a balanced metabolism.
4. Sleep deprivation lowers energy for physical activity
Exercise is a fundamental part of metabolic health. It aids in regulating blood sugar, enhances insulin sensitivity, and helps maintain a healthy weight. However, when you’re sleep-deprived, the motivation and energy for physical activity decrease, leading to a more sedentary lifestyle.
The combination of all the above factors means that poor sleep is often a huge reason for weight gain or an inability to shed those extra pounds.
“I’ve seen it many times. Poor sleep drives up cortisol, which in turn promotes fat storage (especially visceral fat), reduces muscle repair, and impairs glucose handling,” Jonathan said.
“Even if you’re eating clean and moving daily, chronic sleep loss can stall progress or even reverse it. So yes, optimising sleep is sometimes the missing key in body transformation cases.”
What are the key steps to having better sleep?
The advice here is going to be pretty straightforward—but these things are often easier said than done.
First up is maintaining consistency. Going to bed and waking up at the same time each day, even on weekends, can help regulate the body’s natural clock and improve sleep quality.
Exposure to morning sunlight is a good idea, since it sets your circadian rhythm.
Regular exercise and increased fibre intake can also enhance sleep quality and duration. Herbal teas and mind-body tools like yoga nidra or breath regulation can prove to be helpful, too.
You could also consider magnesium supplements, as this ingredient promotes relaxation and eases tension if falling asleep is challenging.
“Each plan is customised, but I always go natural first before even thinking of melatonin or sleep meds,” Jonathan said. “These are usually known as sleep hygiene.”
Can you have too much sleep?
The ideal amount of sleep for most adults ranges between seven and nine hours per night, though individual needs vary.
While little sleep is bad, it turns out that excessive sleep can be a red flag, too.
“If someone consistently needs more than 9–10 hours and still feels groggy, I look deeper—could it be mitochondrial dysfunction, poor sleep quality despite long duration, or even depression? Sleep should be restorative, not excessive compensation,” Jonathan said.
Don’t sleep on sleep
If you’re struggling with weight gain, frequent hunger, sugar cravings, or stress, sleep quality may be a contributing factor.
By focusing on consistent sleep habits and minor changes to your daily routine, you can achieve lasting health benefits that support a balanced metabolism and overall wellness.
- Learn more about RENN Asia Wellness here.
- Read other articles we’ve written about RENN Asia Wellness here.
Featured Image Credit: cottonbro studio via Pexels
