The Importance of Sleep for Weight Loss & General Health

Sleep. Something that (at times) many of us wish we could do all day long (or at the very least, get more of).

In this fast-paced world, many of us fail to get the appropriate amount of sleep that our bodies require.

This lack of sleep comes with many negative health consequences (some of which we will go over later), affecting many of our fitness goals.

When we ask what the optimal amount of sleep is, we usually hear something along the lines of 7-9 hours a night.

I’d say the majority of us know this recommendation. However, many are unaware of the importance of sleep, the effects it has on losing weight and obesity, as well as the negative health consequences that come from inadequate sleep.

In this article, I aim to give you a crash course in sleep and, most specifically, how a lack of sleep impacts our ability to lose weight.


The Importance of Sleep for Weight Loss

In his book, Why We Sleep, the author puts it quite eloquently:

“Sleep is the single most effective thing we can do to reset our brain and body health each day — Mother Nature’s best effort yet at contra-death.”

Sleep for no more than 2 hours for several nights in a row, and you will likely have plenty of physical and mental signs that express why inadequate sleep is not a beneficial thing to your overall health. 

That is some reasonably apparent anecdotal evidence that sleep matters to many different processes of our body. All you have to do is think back on a time when you slept poorly (for one reason or the other), and how you felt afterward. Chances are, you experienced common symptoms like fatigue, inability to focus, irritability, and daytime sleepiness.

Of course, the lack of sleep for just one night may not seem like that big of an issue, especially if you’re still young. In fact, many people report feeling energetic and in a better mood, but don’t fall for that. This is simply a reaction within the brain as a response to the sudden lack of sleep. Your brain releases more endorphins, which, in turn, increase the production of dopamine. The bad news is, this effect is short-lived, and insufficient sleep is going to catch up to you very quickly.

There is plenty of scientific data proving this point, as well.

For example, “Sleeping less than 7 hours per night on a regular basis is associated with adverse health outcomes, including weight gain and obesity, diabetes, hypertension, heart disease and stroke, depression, and increased risk of death”. (1)

Some of the effects associated with sleeping less than 7 hours per night are: (1)

  • impaired immune function
  • increased pain
  • impaired performance
  • increased errors                                                                                                                   
  • greater risk of accidents.

We need sleep to function properly and stay healthy. But things don’t end there. We also need sleep for fitness.

Effects of Sleep on Fat Loss

This is where things get interesting.

Obesity has been closely correlated with short sleep duration…..”As sleep has decreased over time, the prevalence of obesity has increased” (2).

Though correlation does not equal causation, some reasons lack of proper sleep may lead to obesity are; increased food intake, hedonic eating as opposed to hunger-driven eating, fatigue that causes a less physically active individual, as well as overeating. (2)

There’s also evidence that “…short sleep duration is associated with higher total caloric intake, higher absolute intake of fat, and diets with relatively higher fat and lower protein composition, and limited evidence that short sleep duration is associated with lower intake of fruits and vegetables and diets of lower quality.” (3)

The reasons for this correlation of inadequate sleep with negative dietary impacts are likely multi-factorial, including (but not limited to): (3)

  • affected appetite-related hormones (e.g, leptin & ghrelin);
  • pleasure pathways;
  • and increased duration of probable food intake.

More research is needed, however, to determine how poor sleep truly affects diet.

Another important factor worth looking into is energy metabolism within the body. In other words, how sleep (or lack thereof) impacts your body’s ability to burn fat as an energy source as opposed to lean tissue.

In one study from 2010, researchers wanted to determine how sleep length affects fat loss efforts (4). In it, researchers had ten overweight (but otherwise healthy) middle-aged individuals stay in bed for either 8.5 hours (slept around 7 hours and 25 minutes) or 5.5 hours (slept for around 5 hours and 14 minutes) for two weeks. Conditions were swapped at least twelve weeks apart. 

In both conditions, the subjects ate about 1450 calories (which was a reasonably significant caloric deficit for them) and got about 18 percent of their calories from protein (which came out to about 65 grams of protein daily). Essentially, everything but the sleep duration was the same in both conditions, and here is where it gets interesting:

In both cases, subjects lost about 6.6 pounds of weight during the intervention. In the 8.5-hour condition, folks lost about 50 percent fat and 50 percent lean tissue. But, in the 5.5-hour state, participants lost 20 percent fat and 80 percent lean mass. Only a fifth of the weight loss was actual fat.

With all else being the same, sleeping for two more hours each night resulted in roughly 2.3 times more fat loss.

To date, this is one of the best studies that genuinely represents the importance of sleep for effective fat loss.


What IS “Normal Healthy” Sleep and How Much Do We Need?

Normal healthy sleep can be characterized by these four key aspects (5):

– Sufficient duration
– Good quality
– Appropriate timing & regularity
– Absences of sleep disturbances and disorders

In other words, normal healthy sleep is; consistent, quality sleep, with no disturbances, for a sufficient amount of time.

So the million-dollar question is, how much sleep do I need?

The answer is….. It depends!

Not what most of us want to hear, but as with the majority of the different aspects of health, our individuality plays a significant role in the prescription and/or recommendation given.

“..there is no magic number or ideal amount of sleep to get each night that could apply broadly to all. The optimal amount of sleep should be individualized, as it depends on many factors. However, it is a fair assumption to say that the optimal amount of sleep, for most people, should be within the age-appropriate sleep duration recommended ranges.” (6)

The majority of evidence supports the general recommendation that adults aged 18-60 should get seven or more hours of sleep a night (consistently) for optimal health.

A Quick Recap

Though sleep (as a whole) is not fully understood, the importance of it cannot be denied.

Lack of sleep can lead to many issues, such as:

– Decreased ability to burn fat and build muscle;

– Decreased athletic performance;

– Reduced accuracy and explosive strength;

– Reduced testosterone and growth hormone;

– Impaired cognition, memory, ability to focus, and critical thinking;

– General fatigue;

– Increased appetite and cravings;

And even more severe issues, including:

– Anxiety and depression;

– Impulsive behaviors;

– Paranoia;

– Impaired immunity;

– Cardiovascular disease;

– Daytime sleepiness (which can be dangerous, especially for driving and other similar tasks);

– Insulin resistance and an increased risk of developing diabetes;

The most consistently recommended sleep duration for those aged 18-60 for optimal health is seven or more hours of sleep per night (though the actual appropriate amount per individual will vary).

Adequate sleep should always be one of your key focuses when optimal health is the goal.

If you’re struggling in your weight loss, strength, or general health and fitness goals, evaluate the adequacy and quality of the sleep that you’re getting per night.

If you are getting in less than 7 hours, aim to get those numbers up, as well as keeping an eye on your quality of sleep.

I hope this article has helped you in increasing your knowledge of health and fitness.

Please feel free to comment below with your thoughts and/or opinions, as well as what your stance is on sleep and its connection with weight loss, obesity, and overall good health.

Also, don’t forget to share this article if you believe it may benefit a spouse, friend, or relative.

Thanks for reading and best of luck with all of your fitness goals!

Michael Cruz


References & Sources







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