Sleep and weight: How they are connected

Get your diet under control and start exercising, and you’ll be home free. Or is that really the whole truth? What many people don’t know is that your sleep controls your hunger in a way that can affect your weight loss. Here’s what we know about the impact of sleep on your weight and health.

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Acute and chronic sleep deprivation is now almost a pandemic in developed countries. A survey of adults in the US found that one-third of respondents slept less than seven hours per night on average. This is alarming because research shows that sleep is an incredibly important part of human health, especially when it comes to metabolism and weight control.

A review published in the National Library of Medicine highlights the growing body of evidence suggesting that sleep deprivation has negative effects on metabolism and contributes to weight gain in both adults and children. Let’s take a closer look at some of the mechanisms at play here.

Sleep deprivation and weight gain

People who sleep less are more likely to gain weight and develop obesity than those who get enough sleep. Epidemiological studies show that people who sleep an average of 5 hours per night are almost 40% more likely to become overweight than people who sleep an average of 7 hours.

This may seem logical: if you don’t get enough sleep, you are too tired to exercise or go to the gym. This, in turn, will cause you to gain weight. However, it turns out that the relationship between sleep and weight gain is somewhat more complex.

Hormonal reaction in the body during sleep deprivation

When you sleep, your body releases a small amount of growth hormone, which is important for maintaining a healthy metabolism. Although levels are low during the day, they are responsible for increasing the rate at which cells break down fat and convert it into energy. If you don’t get enough sleep and haven’t eaten all night, your body thinks it is in a state of starvation.

In starvation mode, the body activates a survival mechanism that increases levels of the hormone ghrelin, which stimulates hunger, and decreases levels of growth hormone. When you sleep, growth hormone is released naturally, which helps break down stored fat. When you don’t sleep properly, this process is disrupted.

Chronic effects of sleep deprivation

Chronic sleep problems can also alter the body’s metabolic processes, causing weight gain. In a study of adults who participated in a sleep program, researchers found that participants felt less hungry after sleeping 8 hours compared to after sleeping 5 hours. The amount of ghrelin, the hunger-stimulating hormone in the blood, decreased.

Another randomised study found that participants who had slept poorly for two weeks lost as much weight as the group that slept for five hours in the above-mentioned study. However, those who had slept poorly had higher levels of ghrelin and lower levels of growth hormone than the others. They also had higher levels of cortisol, a hormone that promotes fat storage.

Ghrelin and increased hunger during sleep deprivation

Ghrelin, a hormone that increases during sleep deprivation, makes us feel hungry, eat more, and crave fatty foods. Studies show that people who have received ghrelin injections feel hungrier. This has also been seen in injections given to people who have undergone gastric bypass surgery to reduce hunger.

During sleep deprivation, ghrelin levels are significantly higher than when you are well rested. Studies actually show that sleep deprivation can have the same effect on ghrelin levels as fasting. This may be the reason why people who sleep too little and do not eat enough during the day are often drawn to foods high in fat and carbohydrates.

Can lower metabolism

Adenosine is a by-product of the conversion of fats and carbohydrates and makes us feel tired. When we sleep, adenosine levels in the blood rise, which slows down the metabolism. The more adenosine that builds up in the blood during the night, the more tired we feel when we wake up in the morning. In other words, the lethargy you feel when you have sleep problems comes from adenosine building up in the blood and slowing down your metabolism.

Varying levels of adenosine in the bloodstream may be one way that sleep affects weight. Studies suggest that when adenosine levels are high, metabolism slows down, causing people to feel less hungry, eat less, and have a lower metabolic rate.

What we can take away from this

It is clear that sleep is an important part of a healthy lifestyle, with the potential to improve overall quality of life. What is less clear is what we can do to get enough sleep. However, evidence suggests that a helpful and important thing to do when experiencing sleep problems is to have a bedtime routine and to sleep for long enough. This contributes to a better lifestyle and helps you maintain a healthy weight.

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*Weight loss is individual, so we cannot guarantee how much/how quickly you will reach your goal. The important thing is all the health benefits. We distance ourselves from unhealthy ideals and crash diets, and do not recommend calorie counting if you are underweight, ill, or pregnant.