Sleep is quite possibly more important than our diet and exercise combined. It’s probably the most overlooked subject when it comes to losing weight.

The science behind sleep is getting more and more interesting as more things are being discovered. The process of sleep appears to be changing the chemistry within our body which leads to multiple chain reactions that I’ll talk about below.

Here is a list of a few things that happen when we are sleep deprived and therefore why we should prioritise our sleep before anything else when it comes to fitness goals.

  1. The hormones Leptin and Ghrelin go out of balance which causes significantly increased appetite.

    Ghrelin is a hormone released in the stomach that signals hunger. The levels of ghrelin before eating are usually high and low after eating.

    Leptin is released from fat cells and suppresses hunger by signalling fullness in the brain.
    Without adequate sleep, the body produces more ghrelin and less leptin, leaving you hungry and increasing your appetite.

    A study of over a thousand participants found that those who slept for short durations had 14.9% higher Ghrelin and 15.5% lower Leptin levels. The short sleepers also had a higher BMI (Body Mass Index).

    It’s easy to see that this is something we’ve all been through without even realising.
  2. Lack of sleep increases the hormone Cortisol in your blood which can be responsible for storing fat as well as many other side effects because it goes out of balance.
  3. Sleep helps prevent insulin resistance.

    The hormone Insulin is responsible for moving sugar from your bloodstream to your cells so it can be used as fuel. When the insulin resistance increases there is more sugar floating in our blood and we produce extra insulin to help move it out.

    That not only is a precursor for both type 2 diabetes and weight gain but also makes you hungrier and tells your body to store more energy as fat.

    In one study 11 men in a lab were allowed only 4 hours of sleep for six nights and as result, the ability of their bodies to lower blood sugar levels decreased by 40%.
  4. Overweight people often suffer from sleep apnea which is periods of sleep where they can’t breathe properly and the oxygen delivered to the body is too less which makes them even less restful when they wake up.
  5. Your willpower to resist cravings decreases. It is proven that lack of sleep reduces our ability to resist foods as well as make the right choice in many other rational decisions. More cravings equals lower chance of losing any fat in a long run.
  6. When we are sleep deprived there’s a much higher chance to skip our workouts or at least our performance decreases a lot. In addition to that our activity level throughout the day could reduce as well and that obviously will lead to fewer calories burned. (Exactly the opposite of what you need when being on a fat loss journey)
  7. Sleep deprivation causes a decrease in Serotonin. This is a hormone that signals happiness and if it’s decreased the normal sunny day that should be perfect can easily go sideways into frustration and anxiety which leads to another world of chain reactions.

How to optimise Sleep for Fat Loss?

There are multiple things that you can do and should do. Just so I don’t repeat myself I highly recommend you read my other article ”How To Easily Lose Fat Naturally Without Fad Diets Or HIIT Workouts” where you’ll find the ”12 Tips To Optimise Your Sleep For Fat Loss And Optimal Health”.

You’ll also find interesting materials about circadian rhythm and books that I recommend.


I often use one health pyramid to illustrate the importance of Sleep and other factors when it comes to Fat loss or sports performance. Sleep is placed at the bottom and it’s with the highest priority. Whenever I start with a new client I always ask what their sleep hygiene looks like.
The point is that, if you don’t optimise your sleep you’ll struggle to lose weight and even more so to maintain it. Study all the things that I teach you in this article and even join the Coach PK Inner Circle to really dive in and take your fat loss journey to a whole another level.
You should get to the point where you feel relaxed and in control knowing that your fat is never coming back.

Thank you for reading and I hope you found what you’re looking for. If you have any questions or suggestions please shoot me a message through the chatbox.