Is sleep important for weight loss? Many people believe that sleeping too much can lead to weight gain while for others, it is the opposite. One fact that is however very obvious is that sleeping is one of the most naturally healthy habit that can literally change your health profile for the good.
But no matter where you stand, this post promises to take a deeper look into the relationship between sleep and weight loss. Assuming there is any. So you better read till the very end.
Weight watchers are curious about the many different causes of weight gain and try as much as possible to contain them. Just like the issue of weight gain because of stress that that has seen many take up the habit of meditation as well as more sleeping hours.
Hopefully, by the time we are done with this post. The facts would be laid bare and the importance of sleep as it concerns weight loss would no longer be a mystery.
Sleep ‘is a restorative process of the brain, by the brain, and for the brain’, but it is also clearly important for the health of the entire body.
And it is very important that we get deep sleep on a daily basis. Deep sleep occurs during stages 3 and 4 of non-rapid eye movement (REM) sleep and is thought to be the most restorative of all sleep stages.
In 2008, the poll conducted by the National Sleep Foundation revealed that American adults sleep on average 6 hours 40 min during weekdays and 7 hours 25 min during the weekend. In contrast, in 1960, the average sleep duration was 8.5 hours .
Recurrent partial sleep deprivation has been shown to have detrimental effects on carbohydrate metabolism and endocrine function.
Different surveys suggest that obesity epidemic has been paralleled by a trend of reduced sleep. both laboratory and epidemiological studies points to short sleep duration and poor sleep quality as new risk factors for the development of obesity.
Sleep loss has been shown to result in metabolic and endocrine alterations, including decreased glucose tolerance, decreased insulin sensitivity, increased evening concentrations of cortisol, increased levels of ghrelin, decreased levels of leptin, and increased hunger and appetite. 
Many studies has shown a significant association between short sleep of generally 6 hours per night and increased obesity risk. A fact that supports the claim that 8 hours of sleep everyday should be the minimum.
Also, evidence from large epidemiological studies from seven different countries have indicated the existence of a negative association between sleep duration and BMI in both adults and children.
Evidence has pointed to short sleep duration as a novel risk factor for weight gain and obesity. Short sleep duration appears independently associated with weight gain, particularly in younger age groups. 
Another study examined appetite regulation after 2 nights of 4 hours in bed and after another 2 nights of 10 hours in bed. And the result showed decrease in leptin levels. In fact, it was a 18% decrease of leptin levels after the short nights relative to the long nights. The study which also examined ghrelin levels, showed a 28% increase of the hormone after the 2 nights of 4 h in bed.  Several studies have also shown that recurrent partial sleep restriction or experimentally reduced sleep quality results in decreased insulin resistance, another risk factor for weight gain and obesity.
A recent study has shown that reduced sleep quality, without change in sleep duration, can also have adverse effects on glucose metabolism which can lead to weight gain and diabetes.  Conclusively, what the increasing research evidence has shown is that sleep disturbances, including insufficient sleep due to bedtime curtailment and poor sleep quality, may represent novel risk factors for obesity and type 2 diabetes.
The increased risk of obesity is possibly linked to the effect of sleep loss on hormones that play a major role in the central control of appetite and energy expenditure, such as leptin and ghrelin.
Studies have shown that ghrelin, a hormone promoting hunger, increases with sleep restriction, whereas leptin, a hormone contributing to satiety perception, decreases at the same time.
Reduced leptin and increased ghrelin levels correlate with increases in subjective hunger when individuals are sleep restricted rather than well rested.
Adequate sleep duration and quality are important for the normal functioning of daily metabolic and hormonal processes and appetite regulation. 
In another study, it was shown that a 5 day of insufficient sleep increases energy needs, while also increasing food intake such that intake is in excess of energy needed leading to weight gain. Food intake, especially of carbohydrates was high and participants ate smaller breakfasts but ate more over the day. 
Sleep is important for weight loss because it helps to increase the hunger hormone while reducing the satiety hormone, leptin.
A short sleep duration leads to reduced leptin and elevated ghrelin. These differences in leptin and ghrelin are likely to increase appetite, possibly explaining the increased BMI observed with short sleep duration.
These hormone alterations may contribute to the BMI increase that occurs with sleep deprivation.
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An increased in food intake during sleep deprivation appears to be a physiological mechanism for providing the body with the energy needed to sustain extended wakefulness. But when also exposed to the modern obesogenic environment of readily accessible food, weight gain occurs because food intake is more than what is necessary to balance the energy cost of sleep deprivation. [8, 9]
Studies have also shown that both acute sleep deprivation and chronic partial sleep deprivation (sleep restriction) can cause a decrease in serum leptin concentrations. And it is a known fact that Leptin deficiency increases appetite and promotes obesity. 
In a study that involved 30 men and women who were asked to participate in a 2-phase inpatient crossover study in which they spent either 4 hours per night (restricted sleep) or 9 hours per night (habitual sleep) in bed. It was discovered that sleep restrictions may lead to greater propensity to overeat. 
Not only is sleep duration tied to overeating. Data show that a reduction in sleep increases the tendency for not just any kind of foods but foods high in calories, carbs and fat, which may explain the associations observed between sleep and obesity. 
A study of 12 men carried out to check the effect sleep restriction has on food showed that following a 4 hours enforced sleep restriction, subjects consumed 22% more calories on the day after sleep restriction compared to when there were allowed to sleep for 8 hours. 
Sleep restriction has been shown to decrease morning resting metabolic rate in healthy adults. And a lowered resting metabolic rate when combined with increased caloric intake that is usually the norm during sleep restriction. Increases the risk for weight gain and obesity for adults who are habitual short sleepers. 
It is now a fact that the amount of sleeping hours favours the maintenance of fat-free body mass at times of decreased energy intake. Showing that the lack of sufficient sleep may therefore compromise the efficacy of diet-induced weight loss strategies for weight loss gains.
This study showed that recurrent sleep restriction can reduce the efficacy of reduced-calorie diet on excess adiposity while enhancing subjective hunger in overweight individuals. In other words your weight loss regimen when it comes to dieting is made almost ineffective in the face of sleep deprivation. 
Sleep deprivation can also affect how physical active or sluggish we become. Sleep restriction according to one study significantly decreased physical activity after the first night of sleep restriction. The study also recorded lower physical intensity, with less time spent with intense activities. 
Generally, sleep is important for weight loss because it can boast active physical activities, reduce calories intake, reduce appetite, reduce unhealthy cravings and assist with resting metabolic rate plus help with insulin sensitivity.
Conclusively, sleep is one of the core pillars of any weight loss strategy along with exercises and dieting.