Obesity
Obesity is a condition in which the natural energy reserve of a mammal (such as a human), which is stored in fat, is expanded far beyond usual levels to the point where it is believed to pose a health risk to the mammal. Obesity in wild animals is relatively rare, but it's common in domestic animals like barrows and household pets who may be castrated, spayed, overfed and underexercised.
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2 Causes and effects of obesity 3 Treatment of obesity 4 Worldwide distribution of obesity 5 External links 6 References |
'Obesity' is a concept that is being continually redefined. In humans, the current measurement of obesity is the body mass index (BMI).
A person with a BMI over 25 is considered overweight; a BMI over 30 is considered obese. The American Institute for Cancer Research considers a BMI between 18.5 and 25 to be an ideal target for a healthy individual (although several sources consider a person with a BMI of less than 20 to be underweight). The BMI was created in the 19th Century by the Belgian statistician Adolphe Quetelet, and remained largely intact until June 1998 when the BMI was revised downward. This had the effect of changing one's status from "ideal" weight to "overweight" in one day.
The BMI has been subject to fundamental criticism, as it ignores fat distribution in the body (see central obesity), and the fat/muscle proportion in total body weight. This means that a very fit athete with little fat but highly developed, and therefore heavy, muscles could be classified as obese.
Some researchers see a more relevant and simpler measure to be waistline circumference, as this can highlight the dangerous location of body fat close to vital organs.(See Janssen I, et al. 2004.)
In times when food was scarce, the ability to take advantage of rare periods of abundance and use such abundance efficiently was undoubtedly an evolutionary advantage. This is precisely the opposite of what is required in a sedentary society, where high-energy food is available in abundant quantities.
Although some people may have a genetic propensity towards obesity, it is only with the reduction in physical activity and a move towards high-calorie diets of modern society that it has become widespread. Significant proportions of the population in wealthy countries are now obese, and seen to be at risk of ill health.(See e.g. Dr. Fuhrman.)
Obesity is correlated (in population studies) with an increased risk of heart disease, high blood pressure, high cholesterol and triglyceride levels in the blood, (metabolic syndrome X), cancers and diabetes mellitus: these are all common causes of death in developed countries. Osteoarthritis, Gastroesophageal Reflux Disease (GERD) and obstructive sleep apnea syndrome are all direct consequences of obesity through mechanical factors. Diseases of which the risk allegedly increases through obesity are carpal tunnel syndrome and asthma.
Fat distribution in the body is thought to be a major component of the health risk in obesity (through interfering with the functioning of vital organs such as the liver, gallbladder, kidneys, heart, veins and arteries, etc.). Other risk factors may include lifestyle and dietary factors associated with it, or the stress of coping with society's disapproval. It is generally accepted that physical activity levels and good nutrition are essential for avoiding obesity, and for maintaining good health.
Much research focusses on new drugs to combat obesity, which is seen as the biggest health problem facing developed countries. Some nutritionists feel that these these research funds would be better devoted to advice on good nutrition, healthy eating and promoting a more active lifestyle.
The mainstay of the treatment is dietary restriction and physical exercise. A leading nutritionist (Professor Thomas Sanders, the director of the Nutrition, Food & Health Research Centre at KingÃÂÃÂs College London) emphasises the need for balance between activity and consumption:
Some people with a genetic disposition towards obesity find it very difficult to reduce their weight, and more drastic treatments such as drugs that inhibit fat absorption (orlistat) or suppress the appetite (sibutramine). In the presence of diabetes mellitus, there is evidence that metformin as anti-diabetic drugs can assist in weight loss - rather than sulfonylurea derivatives and insulin, which often lead to further weight gain. The thiazolidinediones (rosiglitazone or pioglitazone) can cause slight weight gain, but decrease the "pathologic" form of abdominal fat, and are therefore often used in obese diabetics.
Increasingly, surgery is being used to limit stomach capacity (and thus food intake); this can happen laparoscopically. Ileal bypass reduces the length of the intestine and hence absorbing surface, but has more complications.
Recent research has suggested that some human obesity may be caused by a viral infection. The virus AD-36 has been identified as a cause of obesity in animals.
The United States has one of the highest obesity rates in the world and is the first nation to have obese poor people.
The obesity epidemic is also increasing in Europe, Asia, and throughout the Americas: as the Indian newspaper The Tribune states:
Definiton of obesity
Causes and effects of obesity
Treatment of obesity
A proportion of the patients will be able to lose weight by dieting. However, starvation itself is a strain on the cardiovascular system, and in some people, if the metabolism switches to "starvation mode", it never switches back, making weight regain impossible to avoid. Worldwide distribution of obesity
The spread of obesity is thought to be related to the increasing westernisation of these countries (see the China project), which brings fundamental change in eating habits and decreased levels of physical activity. There is some speculation that some food industries may be delaying attempts to limit the spread of obesity, see the ABC news article. The United states response[1] in November 2003 to the WHO draft strategy on obesity introduced the notion of food industry-sponsored initiatives. These sorts of links with vested interests are regarded with scepticism by some nutritionists[1].External links
References