Sleep and Weight Loss

Not sleeping will make you fat

Most of us have heard that sleep is important for recovery, to process the day or even for our memory, and most of us have experienced how it feels when we did not get a full night of sleep.

But did you know that having irregular sleep, too little sleep or interrupted sleep can lead to weight gain?

What is sleep deprivation and what is the cause of it?

We speak of sleep deprivation when you get less than 5-6h of sleep a night. 1

The causes of poor sleep are broad and go from psychological stress to changes in your social life, like having a baby, or sleeping in a different environment, to hormone imbalances that can lead to difficulties falling and/or staying asleep.

Why do I gain weight when I don’t sleep enough?

Sleep deprivation has an impact on every aspect of our endocrine system which regulates metabolism and body weight.

For example, your cortisol level is highly connected to the circadian rhythm, it usually is the highest in the morning and slowly decreases throughout the day to then reach its lowest point around midnight.2 If your sleep is disrupted it affects your cortisol level and can lead to increased levels during the day leading to a rise in blood sugar and insulin.

Insulin on the other hand is the hormone that makes it possible for glucose to enter the cell to then be used for energy or to be transformed into fat. In other words, if your insulin levels are constantly high, you will gain fat and it will be incredibly difficult to lose weight.

Additionally, high cortisol levels as well as high insulin can interfere with the conversion of the thyroid hormone T4 to T3, leading to a reduced function of those hormones and therefore a downregulated metabolism which also contributes to weight gain.

Besides these major factors did you ever experience that you were hungrier after a night of poor sleep? The cause for increased hunger is that our hunger and satiation hormones Ghrelin and Leptin get out of balance, which makes you want to eat everything you see the next day.3

As you can see it is like a domino effect starting with a poor night sleep. 

What can I do?

It can be incredibly hard and frustrating when it comes to sleep, but there are ways to improve your sleep and to get you back on track.

First, stabilize your blood sugar. Having very high glucose levels before going to bed leads to an overproduction of insulin which then leads to a glucose crash during the night forcing you to wake up. To keep your blood sugar stable, avoid eating high carb or sugary foods and drinks before bed and avoid drinking alcohol.

If you work on your computer, have a smart phone and watch TV at night chances are high you are getting too much blue light inhibiting the production of melatonin. Turn off all electronic devices by 6pm to avoid this issue. If that is not possible you can try to use blue light blocking glasses.

As most of our melatonin is built in our gut, it is important to address gut issues. Talk to your health care provider about possible ways to improve your gut health.

If you have trouble falling asleep supplements like high quality melatonin, GABA, magnesium, and zinc can be useful.

Other ways to improve your sleep are to sleep in a cool, dark room, go to bed and wake up always around the same time and to avoid drinking large amounts of water before going to bed.

In summary:

Sleep has an enormous impact on our overall health. When it comes to weight gain, even one night of poor sleep can kick of a cascade of hormonal imbalances leading to increased fat storage, hunger and decreased satiation, and fat reduction.


  1. Sleep Deprivation: Causes, Symptoms, & Treatment. Sleep Foundation. Published November 3, 2020. Accessed August 6, 2021.
  2. Hirotsu C, Tufik S, Andersen ML. Interactions between sleep, stress, and metabolism: From physiological to pathological conditions. Sleep Sci. 2015;8(3):143-152. doi:10.1016/j.slsci.2015.09.002
  3. Can Overeating Cause Sleep Disturbances? Sleep Foundation. Published November 20, 2020. Accessed August 7, 2021.
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