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In the process of melting fat tissue, besides an individually tailored diet and appropriate, regular physical activity, the third factor that significantly affects the success of this process is – sleep. The quality and duration of sleep are necessary prerequisites for melting fat tissue, as well as for maintaining health in general.
A study looked at how little sleep affects fat loss. It was in the Annals of Internal Medicine. Many people don’t get enough sleep. Researchers tested this on a low-calorie diet. The combination of less sleep and less food was bad. It resulted in slower fat loss. It also caused more lean muscle mass loss.
The study was conducted on two groups of subjects: one group slept 5.5 hours per night, and the other 8.5 hours. Food intake was reduced to 90% of each subject’s basal metabolism. At the end of the study, subjects in both groups lost the same amount, an average of 3 kilograms. However, the ratio of lost fat tissue to muscle mass differed drastically.
- In subjects who slept 8.5 hours, the ratio of lost fat tissue to muscle mass was 50/50.
- However, in subjects who slept 5.5 hours, this ratio was a drastic 20/80 in favor of muscle mass. Thus, only one-fifth of the lost kilograms was fat tissue.
Specifically, the group that slept 8.5 hours lost 2.33x more fat tissue than the group with 5.5 hours of sleep, while the latter lost 1.6x more muscle mass. Therefore, for everyone entering the process of losing excess weight with the goal of maximizing fat loss while maintaining hard-earned muscle mass, sleep is a crucial factor and should be taken seriously.
Therefore, a sufficient amount of sleep is extremely important during a restrictive diet period because sufficient sleep helps preserve lean muscle mass and facilitates the process of fat loss.
Additionally, it is confirmed that a lack of sleep stimulates the enhanced secretion of the hormone ghrelin, which:
- reduces energy expenditure
- encourages feelings of hunger and increased caloric intake
- promotes fat tissue retention
- increases glucose production in the liver (to enhance the availability of this fuel for glucose-dependent tissues).
According to the explanation, enhanced catabolism and consumption of lean muscle mass as a consequence of reduced sleep quantity occurs due to increased conversion of body proteins into glucose in order to satisfy the prolonged metabolic needs of the active brain and other tissues that require glucose for optimal functioning during wakefulness.
A study published in Medical Hypotheses examined how sleep affects muscle recovery on an endocrinological and molecular basis. The conclusions of this study are as follows:
1. Lack of sleep has an anti-anabolic effect
According to the conclusions of this study, a lack of sleep significantly negatively affects the circulating levels of two primary anabolic hormones – testosterone and IGF-1.
- Testosterone directly affects muscle hypertrophy, by binding to androgen receptors, it enters the cell nucleus directly and increases protein transcription and synthesis. Also, testosterone inhibits the activity of other proteins that block the mTOR pathway – the primary cellular pathway for muscle hypertrophy.
- IGF-1 is the second hormone that also plays a significant role in muscle hypertrophy. It also acts via the mTOR pathway, increasing protein synthesis and is responsible for the proliferation and activation of so-called satellite cells.
Therefore, with a lack of sleep, a reduction in the synthesis of muscle proteins occurs at two different levels.
2. Lack of sleep has a catabolic effect
Given the fact that lack of sleep reduces the release of testosterone, testosterone inhibits the effects of myostatin. Myostatin blocks the proliferation and differentiation of satellite cells (which is contrary to the IGF-1 hormone).
Lack of sleep also negatively affects the levels of the stress hormone, cortisol. Acutely elevated cortisol levels are common during physical activity, and this is an expected reaction. However, chronically elevated levels of this hormone can cause a series of negative health consequences. Cortisol blocks protein synthesis by inhibiting the activation of mTOR pathways and activating pathways that lead to the breakdown of muscle proteins.
Therefore, it can be concluded that chronic lack of sleep has the same negative consequences as aging when it comes to the impact on strength, size, and body composition:
- It reduces testosterone levels
- It reduces IGF-1 and growth hormone levels
- It enhances catabolism
Melatonin is a key hormone here. It helps you sleep and improves it. Melatonin also affects growth hormone production. This is vital for IGF-1. Melatonin, growth hormone, and IGF-1 all drop as you age. Less melatonin from poor sleep starts negative effects. This is the result of not sleeping enough.
So, how much sleep is needed?
There’s no universal answer to how much sleep you need. However, experts recommend you wake up without an alarm. Go to bed early enough to get sufficient sleep. This way, sleeping supports all your body’s processes. It won’t act as a hindrance to your health.
