Obesity and the Risk of Fatigue
Obesity is defined as having a body mass index greater than 30 kg/m2. (1) In a healthy person, the ideal BMI is to be between 18 and 25 kg/m2. Overweight is a BMI of 25-29 kg/m2. While body mass index is not a perfect way to measure obesity, it is good enough to give a rough estimate of what a person should be aiming for when they are losing weight, taking into account any abnormalities (very short or very tall people, for example).
Currently, over 25% of the United States is considered obese. (2) This is a rather alarming statistic and the amount of overweight or obese people has gone up significantly throughout the entire world over the past few decades. While scientists, doctors and other boffins struggle to figure out exactly what is going on, the rest of the world attempts to deal with the issue as best as they can. With obesity comes a common phenomenon, excessive tiredness during the day or sleepiness, even drowsiness. (3)
Sleep apnea and obesity
The most serious form of this is called sleep apnea. (4) During the night, a person who is obese has difficulty breathing rhythmically, because of excess body-fat that can partially block the throat. (5) Sometimes breathing may stop for even up to 10-15 seconds while asleep and then resume sporadically. This puts the person into a constant state of shallow sleep, which results in them not getting enough deep sleep rest. During the next day, they are then fatigued and tired, even if they have ‘slept’ for 7-8 hours. (6) What has been noticed in studies on patients who are obese and have sleep apnea, is that even a 10% reduction in body-weight can alleviate or even remove entirely the symptoms. (7)
Sleep apnea and daytime sleepiness have been related to visceral obesity, insulin resistance and even hypercytokinemia. (8) Mainly, obese middle-aged men are the ones susceptible to sleep apnea and can die from accidents related to tiredness as well as cardiovascular events. What’s clear from this is that sleep apnea is strongly related to excess body-weight around the abdomen, insulin resistance that has come about through poor dietary choices that include too many carbohydrates and sugars, as well as hypercytokinemia, a condition that is produced when there are too many cytokines in the body (a hormone secreted from body-fat responsible for regulating appetite).
Stronger links to obesity and metabolic disorder
A more recent study from 2006 determined that sleep apnea is not the primary cause of daytime sleepiness in obese people. (9) It seems that the truth is actually that “obesity per se is associated with objective and subjective daytime sleepiness compared to normal-weight controls regardless of sleep apnea and sleep loss.” (10) Furthermore, it was determined that the primary causes of excessive daytime sleepiness (EDS) were depression and metabolic disturbances, in other words, obesity/diabetes. (11) Insulin resistance, particularly in polycystic ovary syndrome (PCOS) were also associated as was insufficient physical activity. (12) The conclusion was that daytime sleepiness was found to be caused by metabolic factors, whereas fatigue is mostly related to psychological distress. All of this was shown to be through the interaction of the hypothalamic-pituitary-adrenal (HPA) axis and excessive amounts of cytokines in the bloodstream (released by excess body-fat). (13) An even more recent study from 2011 confirmed that “obesity in childhood has now reached epidemic proportions and is a cause of psychosocial problems including low self esteem.” (14) This often continues into adulthood where it can cause “major morbidity, disability, and premature death.” (15)
Stress, obesity and daytime sleepiness
Stress is also a significant factor in daytime sleepiness and fatigue. (16) The exact interaction comes through a hormone normally released from the nervous system, but which can also be released in excess amounts from a person who has too much body-fat. (17) As a person gets more and more obese, the stress hormones become excessive in the body and can cause depression and even anxiety. Coupled with the social stigma associated with obesity, especially amongst children, this can be a recipe for depression and more overeating, leading to even more obesity. Cytokines in excessive amounts have also been shown to cause excessive sleepiness. Therefore, it is clear that imbalances in the metabolism and the endocrine system are a serious problem that needs to be dealt with as soon as possible.
Snoring, obesity and fatigue
Snoring has also been linked to obesity in a number of ways. (18) People who are more obese have a higher propensity of having excess body-fat around their necks and throat, which causes them difficulty in breathing during the night. Also, people with excess body-fat around their abdomens and chest area may snore while they are lying on their backs due to pressure on the lungs and respiratory system. (19) People who snore often wake up during the night as well – whether it’s because of an annoyed partner or because they wake themselves up from light sleep by hearing their snoring. This causes them to have less fitful sleep which makes them tired during the following day. (20)
Obesity, fatigue and diet
According to a lot of recent evidence, it is also an inappropriate diet that is contributing to the epidemic of obesity and tiredness that is sweeping the world. A diet that is high in sugar and carbohydrates ends up providing a largely glucose-based metabolism for the body, but because this is inefficient, especially for muscular function, physical fatigue is probably a predictable outcome of the situation. (21) “The inability to obtain sufficient fuel from glucose on the part of both the muscles and the heart simply saps us of the energy to move around.” (22) Therefore, it’s not the obesity that is making us tired, it is the poor diet that is making us obese and not providing enough energy for us to function properly.