Is Sleep the Missing Link to Weight Loss? Most Certainly!
Sleep and weight loss

Is Sleep the Missing Link to Weight Loss? Most Certainly!

This article is a PERFECT MATCH

… if any of these statements sound interesting:

  • Less sleep is associated with more body fat.
  • Too little sleep makes you buy more crap food.
  • Your body believes it’s hungry because of too little sleep.
  • Your hormones go NUTS on too little sleep.

I heard a lot of hmm-interestings, so let’s jump right in.


What Do the Stats Say?

The stats say Americans are fat.

The stats also say Americans get too little sleep.

Check this out:

Obesity rate and sleep length

Obesity is increasing while sleep length is decreasing. Coincidence? Image credit to Dr. Michael Breus' book The Sleep Doctor's Diet Plan.

Just to clarify: 1/3 are obese, and another 1/3 are overweight (they didn't make it on the list)...

Anyway, while the stats are interesting, they don’t say much about the connection between sleep and weight. It’s just a correlation so far.

Let’s dig deeper.

lack of sleep makes you fatter

Lack of Sleep Makes You Fatter

(*Note: We’ll just look at the connection between sleep and weight. Sleep deprivation has many more nasty side effects… I wrote about it here.)

The claim is clear:

Sleep less --> weigh more.

Let’s digest some science:

  • This American study looked at 68,183 women over a period of 16 years. Conclusion? Sleep 7 hours and you’re fine, sleep 6 hours and you gain weight, sleep 5 or less hours and you gain more weight. [1]
  • This study in Japan looked at 35,247 employees (mostly men) and concluded that “short sleep duration was associated with weight gain and the development of obesity over 1 year in men”. [2]
  • Another American sleep study stated that losing just 16 minutes of sleep per night increased the risk of obesity. [3]
  • In a Stanford University study they looked at the relationship between 1024 people’s sleeping habits and their weight. The data revealed that sleeping less than 8 hours was associated with obesity. [4]


Lack of sleep makes you fatter. That’s what the research of thousands of people tells us.

(Check out this Harvard article for confirmation.)

So, why is that?

Here’s a plausible reason.

Lack of Sleep Makes You Eat More Carbs and Snacks

Lack of sleep makes you crave sweets.

Oh yeah.

A sleepy man can’t resist some M&Ms…

Research backs this up. (Read this, it’s eye-opening.)

  • People were allowed to sleep 5.5 hours on one night and 8.5 hours on another and then measured how many free SNACKS they downed the next day. On less sleep they ate 221 calories more –> if you get too little sleep every day that’s some nasty weight gain due to snacking… [5]
  • The same study stated that the increased snack intake happened between 11pm and 7am… That’s when you could be asleep.
  • Haha, this is a fun study: Grocery shopping on 2 days, once sleep deprived and once after a normal night of sleep. Guess what, sleep deprived grocery shopping ended up with significantly more junk food… [6]
  • In this study they stated that less than 6 hours of sleep resulted in an increase in appetite for high sugar foods. [7]

Apparently, if you don’t sleep enough, you crave more crap food. You eat more crap food but you also buy more crap food… So, never go grocery shopping on too little sleep.

Interesting, right?

Now, why is that?

Because of your hormones. (Yes, this is also true for MEN.)

Before we check out some hormones, let’s recap what we know so far:

Some of the factors contributing to weight loss through better sleep – having more energy for exercising, having less need for the sugary, temporarily energy-boosting snacks that lead to weight gain – are rather obvious and quite easy to understand. – Dr. Michael Breus from The Sleep Doctor’s Diet Plan

Now to the less obvious part.

Your Hormones Go NUTS on Too Little Sleep

lack of sleep makes you go nuts

First of all, what are hormones anyway?

Hormones are chemical messengers in your body. I like how the sleep doctor Dr. Michael Breus puts it: “Hormones act like traffic signs and signals by telling your body what to do and when and making sure its machinery runs smoothly and maintains homeostasis, or balance.”

Cool, huh?

In other words, if hormones go nuts your body gets friggin' lost! It gets off balance.

And that happens on too little sleep.

Let’s learn more.

(By the way, if you’re sceptic now, don’t worry. It’s EASY TO UNDERSTAND and it's some brag-about-knowledge...)

We’ll look at 5 hormones that are affected by sleep and influence weight gain – insulin, ghrelin, leptin, cortisol, and growth hormone.

(Pssst… There’s one more thing: I don’t think that hormones go nuts on too little sleep, that’s just the natural way our body responds to a lack of sleep. Naturally, we would only deprive us of sleep in emergency cases, and the following reaction of the hormones would actually help us survive and not make us fat.)

Insulin Makes You Store Fat

Lack of sleep makes you insulin resistant

No, insulin is not just the diabetes hormone.

Insulin is your major fat-storing hormone (and it’s darn important for survival).

In short: When you have more insulin, you store more fat.

Naturally, insulin reacts to carbohydrates. But, and that’s important now, if you don’t get enough sleep, you become temporarily insulin resistant. [8]

And guess what, this again leads to weight gain. [9]

It's easy: If you don't get enough sleep you become temporarily less sensitive to insulin. This lets you produce more insulin. A higher insulin level makes you store more fat. And more stored fat means more weight.

Okay. That's insulin. One hormone that gets affected by sleep and makes you gain weight.

And it gets worse…

Ghrelin & Leptin: The Remote Control for Your Hunger and Appetite

Remote control…

Cool idea. But it’s not mine, I stole it from Dr. Michael Breus’ book The Sleep Doctor’s Diet Plan.

Here’s what he says:

Two hormones, ghrelin and leptin, hold the remote control for your appetite. Ghrelin is the green light that says, “Go get some food!” Leptin is the red light that says, “Stop eating now!”
– Dr. Michael Breus

Now, what happens if you get too little sleep?

In short:

Too short nights lower the level of leptin and boost the production of ghrelin --> you’re hungrier all day long.


There are different studies that back this up. [10] [11] Sleep less than 6.5 hours and you end up hungrier because of those hormones. Plus it’s even a negative correlation, which means, the less sleep you get, the higher is the production of the hunger hormone ghrelin… Sleep less, be hungrier.

That’s bad news for the people who want to lose weight and get too little sleep… It’s just so much harder, if not impossible to lose weight. It’s hard to fight against the own body. Because the body truly believes you’re hungry even if you’re full.

That sucks. But it explains a lot.

Again, if you get less sleep, you will automatically be hungrier and crave sweets.

What else?

Cortisol, the stress hormone (it gets nasty).

Damn it! Cortisol Causes You to Break Down Muscles for Energy…

lack of sleep makes you break down muscles for energy

My buddies arm wrestling... Yes, a lack of sleep might cause YOU to lose muscles.

You’ve probably heard it before:

Stress causes your body to produce cortisol.


Because if you’re stressed you need additional energy to cope with whatever you’re facing – a tiger, a fight with your arch-enemy, or, more likely, a lot of work…

As you need extra energy, you need the hormone cortisol that converts stored energy into usable energy. So naturally, cortisol is super helpful and helps you be wide awake in the right moments…

Stress increases cortisol.

You know what else also increases cortisol production?

Right, a lack of sleep.

Lack of sleep increases cortisol production, making you store fat and burn muscle. A high cortisol level also increases your appetite. – Dr. Michael Breus

This sucks a ton! Except if you want to lose lean muscle, gain fat, and crave more food…

Let’s jump to the 4th hormone that is affected by sleep and causes weight gain.

Angel --> Human Growth Hormone <-- Devil

Growth hormone keeps you young and sexy

If you get enough sleep you're more likely to produce more HGH and stay young and sexy...

You definitely want a lot of Human Growth Hormone (HGH).

This is the stay young, slim & sexy hormone.

And guess what, HGH production is highest during deep sleep.

If you get less sleep, you automatically get less deep sleep, and therefore less HGH… simple as ABC.

What does HGH do anyway?

HGH decreases the rate at which your cells utilize carbs and increases the rate at which they use fats --> great if you want to lose fat.

Poor sleep reduces HGH. That in turn increases the storage of fat…

That’s just how it is.

So, if you want to stay young, slim & sexy --> get enough sleep.

Lack of Sleep --> Unbalanced Hormones

Hormones dictate many of our body’s functions. And adequate sleep balances our hormones.

In other words: Too little sleep makes your hormones get out of balance.

Here’s again what happens on too little sleep:

  • Insulin is increased (due to short-term insulin resistance) so you store more fat.
  • Leptin is reduced so you eat more because there’s nothing telling you to stop.
  • Ghrelin is increased so you eat more because it’s telling you to do so.
  • Cortisol is increased so you eat more and use muscles as energy.
  • Human Growth Hormone is reduced so you store more glucose as fat.

All in all a lack of sleep makes you more likely to gain weight.

So, if you’re trying to lose weight and different diets didn’t help, you’re probably not getting enough sleep…

Give yourself 30 to 60 minutes more time to sleep and see what happens. Just try it for a week or so.

Try that especially if you want to lose fat and not muscles… (read on.)

One More Fascinating Study

This is a study with dieters. [12]

Group 1: Same diet, 8.5 hours of sleep

Group 2: Same diet, 5.5 hours of sleep

Now, what happened?

Interestingly enough, both groups lost the same amount of weight… Group 1 lost fat and group 2 lost lean body mass (aka muscle mass). That’s one point for more sleep. Another point for more sleep is that group 2 claimed to be much hungrier… This made it harder to stay on the diet.

Want to lose fat? --> Get more sleep.

Sounds easy, right?

It is in theory, but many (especially overweight) people don’t sleep well.

And that’s the crux.

The Double-Edged Sword

Sleep more and lose weight


Welcome to the last part.

Get this:

Being overweight or obese is a double-edged sword. Not only does obesity contribute to sleep problems, but sleep problems can also contribute to obesity. – Shawn Stevenson from Sleep Smarter

We learned that a lack of sleep definitely can make you gain fat. Now, if you’ve gained a lot of fat (for whatever reasons) you probably sleep worse. And that again can make you gain more weight.

In a study from Johns Hopkins University they concluded that losing belly fat improves your sleep. [13]

One really cool way to lose fat is to replace one hour of TV with one hour of sleep. Yes, this simple change could result in substantial weight loss over time. The study suggests that swapping this hour of TV for sleep could result in a loss of more than 14 pounds a year… [14]

So, if you already sleep well, you might just want to get some extra sleep.

Trouble sleeping?

If you don’t sleep well, you might want to check out my article on lifestyle-sleep mistakes. (If you have serious sleep disorders you want to check with your doctor.)

Hear how sleep research specialist Eve Van Cauter called sleep deprivation: “The royal route to obesity.”


Don’t get enough sleep and you’re on the royal route to obesity…

I love that term. And now that you’ve read the article you know it’s true.

So let’s get to the conclusion.


Get more sleep.

I’m excited.

We’ve learned some really cool facts about the sleep/weight connection.

Let’s sum it up.

The stats say Americans are fat and don’t get enough sleep.

Many studies state there actually is a causation: A lack of sleep makes people fat.

And studies back this up: A lack of sleep makes people eat more crap food.

This has to do with an imbalance of our hormones due to a lack of sleep.

  • Insulin is increased (due to short-term insulin resistance) so you store more fat.
  • Leptin is reduced so you eat more because there’s nothing telling you to stop.
  • Ghrelin is increased so you eat more because it’s telling you to do so.
  • Cortisol is increased so you eat more and use muscles as energy.
  • Human Growth Hormone is reduced so you store more glucose as fat.

In short: If we get too little sleep our hormones play against us. The odds are against us. It’s simple: Too little sleep is the royal route to obesity…

Get this (it stars HULK):

You see, it isn’t always about willpower. So many amazing and strong people fail at weight loss because they’ve unknowingly stacked conditions against themselves. By being sleep deprived, your inner incredible hulk highjacks your brain and you can’t resist doing the very activity that you promised yourself not to do. – Shawn Stevenson

AWESOME! Your inner incredible hulk…

This is so true!

No wonder a sleepy man can’t resist M&Ms… Hulk wants them so badly.

What else did we learn?

Well, you might lose weight on too little sleep, but just the wrong weight, namely muscles… So if you want to lose fat (and that’s what you want to lose), you need enough sleep. (How much is enough? Check my article here.)

And last but not least the double-edged sword:

Being overweight contributes to poor sleep. And poor sleep makes people overweight…

What’s the solution?


Cut an hour of TV and go to bed. This alone can help you lose weight.

The right diet could help too. Remember? Less belly fat improves the quality of your sleep. (Check out what Nils and I eat here…)

The credo is: Get enough sleep or you might end up being heavier than you like (because the odds on too little sleep are against you).

Here’s the conclusion in the short form:

The research is clear and conclusive: Giving your body the rest it needs will enable you to lose weight even if you do not alter your diet or fitness routine. Furthermore, no matter how conscientious you are about what you eat and how active you are, a poor sleep pattern is likely to torpedo your good intentions and allow those extra pounds to creep onto your body and stay there! – Dr. Michael Breus

Alright. That's it from my side. Now it's your turn. Tell me, have you experienced yourself that a lack of sleep led to a hungrier you? Leave a comment below.

Jonas Salzgeber

What's up? My name's Jonas. I'm Swiss (not Swedish). I'm a life enthusiast and I'm curious about everything that gives me an advantage, boost, level upgrade... "That drink will make me unbeatable? I'll down it!" Haha. My motto? Go to bed a little wiser every day & be the best version of yourself.

  • Great article Jonas! I learned a lot from this article. It was very well presented and all is really common sense. It’s too bad we’ve lost our common sense nowadays.


  • […] This is a guest post by Jonas Salzgeber. A more detailed version of the post has previously been published on his personal blog. […]

  • This is really interesting, You are a very skilled blogger. I have joined your feed and look forward to seeking more of your fantastic post. Also, I have shared your web site in my social networks!

  • Stacey McGregor says:

    Great article Jonas. Women who sleep less than 7 hours tend to gain more weight and it’s more difficult to lose weight for them.

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