how lack of sleep affects weight loss

In today’s anxiety-filled, fast paced society of busy and overloaded schedules, it is no wonder that people have resorted to shortchanging themselves on the number of hours they spend sleeping. And this could equally be the reason why one-third of adults in the United States report of sleeping for less than seven hours per night. This development is however very disturbing as several recent studies have found that lack of sleep may actually be keeping individuals from losing weight.

High quality, healthy and consistent sleep cycles have been shown to have substantial impact on metabolic health by balancing the hormones responsible for appetite, food cravings and overeating. Lack of adequate night sleep not only makes us tired but research now has it that it can also inhibit weight loss thus increasing the risk of type 2 diabetes and heart related diseases, as well as decreasing longevity.

Sleep’s effect on body weight is somewhat directly or indirectly connected to its effect on certain hormonal changes that promote weight gain. Of particular interest is how sleep affects insulin, leptin, and ghrelin – all hormones that play significant roles in regulating appetite. Also of significance is the role of fatigue and stress – both side effects of lack of sleep – which can cause an increase in the secretion of the stress-hormone, cortisol.

It has long been suggested that there was a sort of relationship between sleep and appetite. Following this hypothesis, researchers at the University of Chicago after studying the levels of leptin and ghrelin in 12 men, found that sleep deprivation actually triggers the appetite and increases the likelihood of weight gain. This conclusion was arrived at because the experiment showed a significant decrease in leptin levels and an increase in ghrelin levels when sleep was restricted for the participants. The participants also indicated a 45 percent increased appetite for high-carbohydrate, calorie-dense foods.

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The particular hormones investigated in this study were leptin and ghrelin. Leptin is derived from the Greek word meaning "thin", and is a protein hormone produced by fat cells (adipose tissues) that send signals to the hypothalamus of the brain notifying it that the body has eaten enough calories and should therefore stop eating. Leptin thus functions as a natural biochemical appetite-suppressant that makes you feel full and satisfied.

However, when leptin levels are low as is occasioned by loss of sleep, an individual finds it difficult to keep hunger and appetite in check. Also, loss of sleep deprives such individuals the adequate secretion of the sleep hormone – melatonin. Melatonin has been shown to have the ability to assist in the healing of leptin receptors as well as in restoring normal leptin sensitivity which is very important for healthy weight loss and fat burning.

Leptin resistance or insensitivity is often caused by the "de-sensitization" of the brain to the effect of leptin or the inability of the chemical signal from the secreted leptin hormone to cross the blood-brain barrier. The inability of crossing the blood-brain barrier could be due to the inflammation of the arteries caused by excess fat in the bloodstream or the low cerebrospinal fluid (CSF) to plasma ratio – both which are common in overweight and obese people. Not receiving the leptin signals or interpreting them correctly causes the brain not to receive the "I’m full" notification and thus the individual tend to continue eating.

On the contrary, loss of sleep causes an increase in the secretion of the hunger-promoting hormone, ghrelin. Ghrelin is secreted by the cells in the lining of the stomach and stimulates appetite. It is the hormone responsible for the inability of millions of dieters being unable to keep up with their diet plans. It has especially hampered the effort of those who embark on calorie restricted diets in order to lose weight as the body simply secretes more and more ghrelin to increase appetite resulting in uncontrollable hunger and eventual overeating.

Corroborating this influence of sleep on these hormones, a study carried out by researchers at the University of Bristol found that people who had a five-hour per night sleep had a 15 percent drop in the production of leptin and an equally interesting 15 percent increase in the production of ghrelin when compared to individuals who had an eight-hour per night sleep. This study equally concluded that sleep deprivation may trigger appetite and craving for sugar-rich, calorie-dense foods like the earlier mentioned study.

Another hormone which is also affected by lack of adequate sleep is insulin. Insulin helps to maintain the amount of glucose in the bloodstream by ensuring that excess glucose is removed from the bloodstream and taken up to be stored by the liver and muscles as glycogen and as fat in fat cells (adipose tissues).

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However, the research at the University of Bristol cited earlier, also indicated that loss of sleep disturbs glucose metabolism and insulin sensitivity and can thus also lead to hunger and weight gain. Insulin resistance (when insulin becomes insensitive) also leads to the accumulation of excess amount of glucose in the bloodstream leading to excess buildup of fat in the liver as well as buildup of fat and damages to the delicate inner endothelial lining of the coronary arteries – a predisposition to coronary artery disease.

Apart from the above hormones, a neurotransmitter (chemical used by nerve cells to communicate with one another), serotonin, has equally been shown to be affected by loss of sleep. Serotonin as a neurotransmitter functions by maintaining a relaxed feeling or mood, sleep patterns, as well as regulating the feeling of fullness or satiety that tells a person to stop eating.

Low levels of serotonin causes increased irritability and mood swings as well as the craving for carbohydrate- and fat-rich foods such as cookies, roasted nuts, chocolates, cakes and potato chips. These foods all have the tendency to cause short-term increase in blood sugar and provide a surge of energy even though the body does not need them and are later stored as body fat. Also, one notable feature of depression is the reduction in the amount of serotonin in the brain. Irritability, mood swings, and depression are all conditions that generally predispose an individual to pathological eating behaviors.

Finally, and closely related to the last point above, is the fact that sleep deprivation results in higher levels of the stress hormone – cortisol. Several studies have found that fat cells around the belly love to attract cortisol and tend to cause weight gain around the abdominal areas vs. the hips. This type of fat deposition is referred to as "toxic fat" because it is strongly associated with the development of heart disease and stroke.

Although disruption in sleeping patterns and sleep deprivation may not be the main reason for the growing obesity epidemic, it nonetheless poses a great threat and thus can safely be considered as one of the major reasons causing people to become overweight. As should be evident by now, there must be a hormonal balance in order to achieve any significant weight loss success.

Therefore it becomes important to make having adequate night sleep a priority and stop being a victim of today’s hectic and stressful lifestyle. You need at least the recommended 7-8 hours of good night sleep as an adult to have an improved healthy life and optimum weight loss potential. There is no substitute for adequate sleep.