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Sleep loss can be detrimental to your fitness goals because it can negatively influence your ability to lose weight and your ability to maximize building muscle mass and strength.

If you’re an active individual then sleep is sacred because sleep is when your body takes the time and energy to repair and regenerate muscle that has been broken down during exercise. If you’re giving 100% in the gym but not focusing on recovery you could be missing out on a lot of muscle mass. If you care less about building muscle, consider that muscle is a key component to a fast metabolism in order to burn fat and lose weight. Whether your goal is to lose weight, increase muscle mass or maintain peak performance then prioritize getting at least 7-9 hours of sleep each night of the highest quality possible. 


Sleep Deprivation Causes Weight Gain

Sleep deprivation has been shown to cause weight gain because it increases cortisol levels and throws your appetite out of whack. You have two key hormones that regulate your appetite, the first is leptin which is the hormone that suppresses appetite and the second is ghrelin which is the hormone that stimulates appetite. Sleep deprivation causes a decrease in leptin, so you don’t feel as full and increases ghrelin, so you feel hungrier.

The result? You are more likely to eat more.

But wait, it doesn’t stop there.

Sleep deprivation increases the secretion of the stress hormone cortisol, and your body responds by wanting to store more body fat.

So, not only is your appetite not working in our favour by increasing the likelihood that we will eat more but your body stores more body fat. What’s worse is that sleep deprivation increases poor eating choices. Research has shown that you begin to crave high-calorie foods and because sleep deprivation can negatively affect your mood, you are more likely to reach for foods that will make you feel better.

Research has confirmed that individuals who consistently get poor quality sleep have a higher body mass index. Among menopausal women only 23% of good sleepers were obese, whereas 44% of poor quality sleepers were obese.   

One key to weight loss is to get your hunger hormones to work in your favour by controlling leptin and ghrelin and ensuring your cortisol levels low. The best way to get a head start is to focus on getting good quality sleep every night.

Sleep Deprivation Reduces Fat Loss and Increases Muscle Loss

One study showed that sleep deprivation causes surprisingly significant adverse effects on muscle and fat loss. Two groups were put on a moderately calorie restricted diet over 2 weeks. One group got 8.5 hours of sleep each night, while the other group got 5.5 hours of sleep.

The group that was sleep deprived on 5.5 hours of sleep each night lost 60% more muscle than the group who got adequate sleep and lost 55% less fat.

The sleep deprived subjects even felt hungrier, weren’t as satisfied after meals and did not have as much energy to exercise.

Researchers replicated the above study one year later and similarly found that sleep deprived individuals on 5.5 hours of sleep had 60% less muscle mass while those who got 8.5 hours of sleep had gained 40% muscle mass.

So, losing sleep will decrease muscle mass and reduce your ability to lose fat, while getting enough sleep helps to gain muscle, which in the long run will help to lose body fat. Again, the key to lose weight and gain muscle is to get good quality sleep.


Sleep Deprivation Decreases Critical Hormone Release 

During sleep is when your body releases the majority of hormones responsible for muscle growth, improving muscle function and athletic performance. These hormones include testosterone, growth hormone and insulin-like growth factor-1 (IGF-1). It is only logical then that sleep deprivation decreases testosterone, growth hormone and insulin-like growth factor-1 (IGF-1) which can result in muscle atrophy.

Testosterone is a key anabolic factor that is necessary to build muscle and strength. During sleep is when the majority of testosterone is released. One study showed that depriving healthy males of sleep – measured by 5 hours of sleep a night over 7 days – decreased daytime testosterone levels by 10-15%.

In addition, growth hormone is released the most during the first hour to two hours of sleep, which then signals to your body to produce insulin-like growth factor. If you aren’t getting enough sleep, you are significantly reducing the critical hormones your body needs to repair and grow new muscle and enable you to be in peak shape for performance.

Sleep Deprivation Decreases Protein Synthesis

Sleep deprivation also decreases protein synthesis which is your body’s ability to build muscle. if you’re not getting enough sleep you are not allowing your body to repair and build muscle which inhibits full muscle recovery after exercise and can result in muscle loss.

Sleep Deprivation Decreases Physical Performance

Athletic performance is adversely affected from sleep deprivation. Due to a lack of feeling rested, your energy and drive is significantly reduced which causes poor performance. In addition, poor sleep quality and quantity is associated with an imbalanced autonomic nervous system which results in symptoms as if you were overtraining.

The bottom line is that sleep plays a major role in helping you achieve your weight loss and fitness goals, so don’t skip out on sleep.