Obesity is a major public health concern because it predisposes the individual to many disorders, such as noninsulin-dependent diabetes, hypertension, stroke, and coronary artery disease, and has been associated with an increased incidence of certain cancers, notably cancers of the colon, rectum, prostate, breast, uterus, and cervix. In contemporary American society, obesity also carries with it a sometimes devastating social stigma. Obese people are often ostracized, and discrimination against them, especially in hiring and promotion, is common.
Obesity research has yielded a complicated picture of the underlying causes of the condition. The simple cause is ingestion of more calories than are required for energy, the excess being stored in the body as fat. Inactivity and insufficient exercise can be contributing factors; the less active the person, the fewer calories are needed to maintain normal body weight. Overeating may result from unhealthful patterns of eating established by the family and cultural environment, perhaps exacerbated by psychological distress, an emotional dependence on food, or the omnipresence of high-calorie foods.
In some cases, obesity can come from an eating disorder. It has been shown, for example, that binging for some people releases natural opiates in the brain, providing a sense of well-being and physical pleasure. Other studies have found a strong relationship between obesity in women and childhood sexual abuse.
Some weight-loss experts see obesity as based upon genetics and physiology rather than as a behavioral or psychological problem. For example, rat studies have shown that fat cells secrete a hormone that helps the rat's brain assess the amount of body fat present. The brain tries to keep the amount of that hormone (which also appears to act on the brain area that regulates appetite and metabolic rate) at a set level, resulting in the so-called set point—a weight that the body comes back to, even after resolute dieting. The gene that encodes this hormone, called the obese or ob gene, has been isolated in both rats and humans. In addition, a gene that influences obesity and the onset of diabetes has been identified. It has been estimated that from 8 to 30 different genes may influence obesity.
Radical treatments for weight loss have included wiring shut the jaw, stapling the stomach, and intestinal bypass operations circumventing a large area of the small intestine, limiting the area where food is absorbed. The "diet pills" of the 1960s, essentially amphetamines such as Dexedrine, are now seldom prescribed for weight loss. Fenfluramine and dexfenfluramine, drugs formerly used to achieve short-term weight loss, were withdrawn from the market following concerns that they could cause heart valve damage. Drugs available by the late 1990s included sibutramine (Meridia), which is an appetite suppressant, and orlistat (Xenical), which acts to block absorption of dietary fat in the intestine. In 2007 an over-the-counter version of orlistat was approved by the Food and Drug Administration.
Although the study of obesity is yielding many possibilities for treatment, the main focus remains diet (especially a diet limiting fat calories) and exercise, often coupled with emotional and behavioral support. The long-term weight-loss success of most attempts at dieting, however, is notoriously low. Groups such as Overeaters Anonymous, modeled after Alcoholics Anonymous, give support to people with weight problems and eating disorders.
Excessive body fat. It is usually caused by sedentary habits and a diet high in fat, alcohol, or total calories. Calories consumed but not used are stored as fat. Rare causes include glandular defects and excess steroids (see Cushing syndrome). Obesity raises the risk of heart disease and diabetes mellitus. Treatment, by reducing calorie intake and increasing exercise, is best undertaken with a doctor's advice.
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Obesity is a condition in which excess body fat has accumulated to such an extent that health may be negatively affected. It is commonly defined as a body mass index (BMI = weight divided by height squared) of 30 kg/m2 or higher. This distinguishes it from being overweight as defined by a BMI of between 25–29.9 kg/m2.
Excessive body weight is associated with various diseases, particularly cardiovascular diseases, diabetes mellitus type 2, obstructive sleep apnea, certain types of cancer, and osteoarthritis. As a result, obesity has been found to reduce life expectancy. The primary treatment for obesity is dieting and physical exercise. If this fails, anti-obesity drugs and (in severe cases) bariatric surgery can be tried.
Obesity arises from too much energy intake compared with a person's basal metabolic rate and level of physical exercise. Excessive caloric intake and a lack of physical activity in genetically susceptible individuals is thought to explain most cases of obesity, with purely genetic, medical, or psychiatric illness contributing to only a limited number of cases. With rates of adult and childhood obesity increasing, authorities view it as a serious public health problem.
Although obesity is often stigmatized in the modern Western world, it has been perceived as a symbol of wealth and fertility at other times in history.
Body mass index or BMI is a simple and widely used method for estimating body fat mass. BMI was developed in the 19th century by the Belgian statistician and anthropometrist Adolphe Quetelet. BMI is an accurate reflection of body fat percentage in the majority of the adult population. It is less accurate in people such as body builders and pregnant women in whom body composition is affected.
where is the subject's weight in kilograms and is the subject's height in metres.
|Less than 18.5||underweight|
|30.0–34.9 is||class I obesity|
|35.0–39.9||class II obesity|
|Over 40.0||class III obesity|
Some modifications to the WHO definitions have been made by particular bodies:
The surgical literature breaks down "class III" obesity into further catergories.
In those with a BMI under 35, intra-abdominal body fat is related to negative health outcomes independent of total body fat. Intra-abdominal or visceral fat has a particularly strong correlation with cardiovascular disease. In a study of 15,000 subjects, waist circumference also correlated better with metabolic syndrome than BMI. Women who have abdominal obesity have a cardiovascular risk similar to that of men. In people with a BMI over 35, measurement of waist circumference however adds little to the predictive power of BMI as most individuals with this BMI have an abnormal waist circumferences.
The absolute waist circumference (>102 cm in men and >88 cm in women) or waist–hip ratio (>0.9 for men and >0.85 for women) are both used as measures of central obesity.
Body fat percentage is total body fat expressed as a percentage of total body weight. It is generally agreed that men with more than 25% body fat and women with more than 33% body fat are obese. Body fat percentage can be estimated from a person's BMI by the following formula:
This formula takes into account the fact that body fat percentage is 10% greater in women then in men for a given BMI. It recognizes that a person's percentage body fat increases as they age even if their weight remains constant. The results have an accuracy of 4%.
Direct attempts to determine body fat percent are difficult and often expensive. One of the most accurate methods is to weigh a person underwater which is known as hydrostatic weighting. Two other simpler and less accurate methods for measuring body fat therefore have historically been used. The first is the skinfold test, in which a pinch of skin is precisely measured to determine the thickness of the subcutaneous fat layer. It has not, however, been adequately evaluated in obese subjects. The other is bioelectrical impedance analysis which uses electrical resistance. Bioelectrical impedance however has not been shown to provide an advantage over BMI. Therefore the routine use of these tests are discouraged. Body fat percentage measurement techniques used mainly for research include computed tomography (CT scan), magnetic resonance imaging (MRI), and dual energy X-ray absorptiometry (DEXA). These techniques provide very accurate measurements, but it may be difficult to scan the severely obese due to weight limits of the equipment and insufficient diameter of the CT or MRI scanner.
Health consequences can be categorized by the effects of increased fat mass (osteoarthritis, obstructive sleep apnea, social stigmatization) or by the increased number of fat cells (diabetes, cancer, cardiovascular disease, non-alcoholic fatty liver disease). Increases in body fat alter the body's response to insulin, potentially leading to insulin resistance. Increased fat also creates a proinflammatory state, increasing the risk of thrombosis.
Central obesity, characterized by its high waist to hip ratio, is an important risk for metabolic syndrome. Metabolic syndrome is a combination of medical disorders which often includes diabetes mellitus type 2, high blood pressure, high blood cholesterol, and triglyceride levels.
Obesity is related to a variety of other complications. Some of these are directly caused by obesity and others are indirectly related through mechanisms sharing a common cause such as poor diet or a sedentary lifestyle. The strength of the link between obesity and specific conditions varies. One of the strongest is the link with type 2 diabetes. Excess weight is behind 64% of cases of diabetes in men and 77% in women.
|Medical field||Condition||Medical field||Condition|
|Endocrine and reproductive||Respiratory|
In people with heart failure, those with a BMI between 30.0–34.9 had lower mortality then those with a normal weight. This has been attributed to the fact that people often lose weight as they become progressively more ill. Similar findings have been made in other types of heart disease. People with class I obesity and heart disease do not have greater rates of further heart problems than people of normal weight who also have heart disease. In people with greater degrees of obesity, however, risk of further events is increased. Even after cardiac bypass surgery, no increase in mortality is seen in the overweight and obese. One study found that the increased survival could be explained by the more aggressive treatment obese people receive after a cardiac event.
Despite the widespread availability of nutritional information in schools, doctors' offices, on the internet and on product packaging, it is evident that overeating remains a substantial problem. In the period of 1971–2000, obesity rates in the United States increased from 14.5% to 30.9%. During the same time period, an increase occurred in the average amount of calories consumed. For women, the average increase was 335 calories per day (1542 calories in 1971 and 1877 calories in 2004), while for men the average increase was 168 calories per day (2450 calories in 1971 and 2618 calories in 2004). Most of these extra calories came from an increase in carbohydrate consumption rather than an increase in fat consumption. The primary sources of these extra carbohydrates are sweetened beverages, which now accounts for almost 25 percent of daily calories in young adults. Dietary trends have changed with reliance on energy-dense fast-food meals tripling between 1977 and 1995, and calorie intake from fast food quadrupling over the same period. In the early 1980s, the administration of Ronald Reagan lifted regulations limiting the advertising of sweets and fast food to children, and advertisement of these products directed towards children has increased. Agricultural policy and techniques in the United States and Europe have led to lower food prices. In the United States, subsidization of corn, soy, wheat, and rice through the U.S. farm bill has made the main sources of processed food relatively cheap compared to fruits and vegetables.
There is little evidence to support the commonly expressed view that some obese people eat little yet gain weight due to a slow metabolism. What has been found, however, is that some obese people underreport how much food they consume compared to those of normal weight.
In 2000 the CDC estimated that more than 40% of the US population was sedentary, another 30% was active but not sufficiently and less than 30% had an adequate level of physical activity. There has been a trend toward decreased physical activity in part due to increasingly mechanized forms of work, changing modes of transportation, and increasing urbanization. A study from China found urbanization reduces daily energy expenditure by about 300–400 kcal and going to work by car or bus reduced it by a further 200 kcal. Obesity rates have increased in relation to expanding suburbs. This has been attributed to increased time spent commuting, leading to less exercise and less meal preparation at home. Driving one's children to school has become increasingly popular. In the USA the proportion of children who walk or bike to school declined between 1969 (42%) and 2001 (16%) resulting in less exercise. Studies in children and adults have found an association between the number of hours of television watched and the prevalence of obesity.
The percentage of obesity that can be attributed to genetics varies from 6% to 85% depending on the population examined. The thrifty gene hypothesis postulates that certain ethnic groups may be more prone to obesity in an equivalent environment. Their ability to take advantage of rare periods of abundance by storing energy as fat would be advantageous during times of varying food availability, and individuals with greater adipose reserves would be more likely survive famine. This tendency to store fat, however, would be maladaptive in societies with stable food supplies. This is the presumed reason that Pima Indians, who evolved in a desert ecosystem, developed some of the highest rates of obesity when exposed to a Western lifestyle.
Certain medications may cause weight gain or changes in body composition; these include insulin, sulfonylureas, thiazolidinediones, atypical antipsychotics, antidepressants, steroids, sulfonylureas, certain anticonvulsants (phenytoin and valproate), pizotifen, and some forms of hormonal contraception.
The correlation between social class and BMI varies globally. A review in 1989 found that in developed countries women of a high social class were less likely to be obese. No significant differences were seen among men of different social classes. In the developing world, women, men, and children from high social classes had greater rates of obesity. An update of this review carried out in 2007 found the same relationships, but they were weaker. The decrease in strength of correlation was felt to be due to the effects of globalization.
Many explanations have been put forth for associations between BMI and social class. It is thought that in developed countries, the wealthy are able to afford more nutritious food, they are under greater social pressure to remain slim, and have more opportunities along with greater expectations for physical fitness. In the developing world the ability to afford food, high energy expenditure with physical labor, and cultural values favoring a larger body size are believed to contribute to the observed patterns. Attitudes toward body mass held by people in one's life may also play a role in obesity. A correlation in BMI changes over time has been found between friends, siblings, and spouses.
Smoking has a significant effect on a individual's weight. Those who quit smoking gain an average of 4.4 kilograms for men and 5.0 kg for women over ten years. Changing rates of smoking however have had little effect on the overall rates of obesity.
Flier summarizes the many possible pathophysiological mechanisms involved in the development and maintenance of obesity. This field of research had been almost unapproached until leptin was discovered in 1994. Since this discovery, many other hormonal mechanisms have been elucidated that participate in the regulation of appetite and food intake, storage patterns of adipose tissue, and development of insulin resistance. Since leptin's discovery, ghrelin, orexin, PYY 3-36, cholecystokinin, adiponectin, as well as many other mediators have been studied. The adipokines are mediators produced by adipose tissue; their action is thought to modify many obesity-related diseases.
Leptin and ghrelin are considered to be complementary in their influence on appetite, with ghrelin produced by the stomach modulating short-term appetitive control (i.e. to eat when the stomach is empty and to stop when the stomach is stretched). Leptin is produced by adipose tissue to signal fat storage reserves in the body, and mediates long-term appetitive controls (i.e. to eat more when fat storages are low and less when fat storages are high). Although administration of leptin may be effective in a small subset of obese individuals who are leptin deficient, most obese individuals are thought to be leptin resistant and have been found to have high levels of leptin. This resistance is thought to explain in part why administration of leptin has not been shown to be effective in suppressing appetite in most obese subjects.
While leptin and ghrelin are produced peripherally, they control appetite through their actions on the central nervous system. In particular, they and other appetite-related hormones act on the hypothalamus, a region of the brain central to the regulation of food intake and energy expenditure. There are several circuits within the hypothalamus that contribute to its role in integrating appetite, the melanocortin pathway being the most well understood. The circuit begins with an area of the hypothalamus, the arcuate nucleus, that has outputs to the lateral hypothalamus (LH) and ventromedial hypothalamus (VMH), the brain's feeding and satiety centers, respectively.
The arcuate nucleus contains two distinct groups of neurons. The first group coexpresses neuropeptide Y (NPY) and agouti-related peptide (AgRP) and has stimulatory inputs to the LH and inhibitory inputs to the VMH. The second group coexpresses pro-opiomelanocortin (POMC) and cocaine- and amphetamine-regulated transcript (CART) and has stimulatory inputs to the VMH and inhibitory inputs to the LH. Consequently, NPY/AgRP neurons stimulate feeding and inhibit satiety, while POMC/CART neurons stimulate satiety and inhibit feeding. Both groups of arcuate nucleus neurons are regulated in part by leptin. Leptin inhibits the NPY/AgRP group while stimulating the POMC/CART group. Thus a deficiency in leptin signaling, either via leptin deficiency or leptin resistance, leads to overfeeding and may account for some genetic and acquired forms of obesity.
The main treatment for obesity consists of dieting and physical exercise. Diet programs may produce weight loss over the short term, but keeping this weight off can be a problem. It often requires making exercise and a lower calorie diet a permanent part of a person's lifestyle. In the general population only 20% are successful at long-term weight loss maintenance. In a more structured setting, however, 67% of people who lost greater then 10% of their body mass maintained or continued to lose weight one year later. An average maintained weight loss of more then 3 kg or 3% of total body mass could be sustained for five years. There are significant benefits to weight loss. In a prospective study, intentional weight loss of any amount was associated with a 20% reduction in all-cause mortality.
Diets to promote weight loss are generally divided into four categories: low-fat, low-carbohydrate, low-calorie, and very low calorie. A meta-analysis of six randomized controlled trials found no difference between the main diet types (low calorie, low carbohydrate, and low fat), with a 2–4 kilogram weight loss in all studies.
Low-calorie diets usually produce an energy deficit of 500–1000 calories per day, which can result in a 0.5 kilogram weight loss per week. They include the DASH diet and Weight Watchers among others. The National Institutes of Health reviewed 34 randomized controlled trials to determine the effectiveness of low-calorie diets. They found that these diet lowered total body mass by 8% over 3–12 months.
Low-fat diets involve the reduction of the percentage of fat in one's diet. Calorie consumption is reduced but not purposely so. Diets of this type include NCEP Step I and II. A meta-analysis of 16 trials of 2–12 months' duration found that low-fat diets resulted in weight loss of 3.2 kg over eating as normal.
Low carbohydrate diets such as Atkins and Protein Power are relatively high in fat and protein. They are very popular in the press but are not recommended by the American Heart Association. A review of 94 trials found that weight loss was associated with decreased calorie consumption rather than any special properties of reduced carbohydrate consumption. No adverse affect from low carbohydrate diets were detected.
Very low calorie diets provide 200–800 kcal/day while maintaining protein intake and limiting calories from both fat and carbohydrates. They subject the body to starvation and produce an average weekly weight loss of 1.5–2.5 kilograms. These diets are not recommended for general use as they are associated with adverse side effects such as loss of lean muscle mass, increased risks of gout, and electrolyte imbalances. People attempting these diets must be monitored closely by a physician to prevent complications.
With use, muscles consume energy derived from both fat and glycogen. Due to the large size of leg muscles, walking, running, and cycling are the most effective means of exercise to reduce body fat.
A meta-analysis of 43 randomized controlled trials by the Cochrane Collaboration found that exercising alone led to limited weight loss. In combination with diet, however, it resulted in a 1 kilogram weight loss over dieting alone. A 1.5-kilogram loss was observed with a greater degree of exercise. Even though exercise as carried out in the general population has only modest effects, a dose response curve is found, and very intense exercise can lead to substantial weight loss. During 20 weeks of basic military training with no dietary restriction, obese military recruits lost 12.5 kg.
There are two commonly prescribed medications for obesity. One is orlistat, which reduces intestinal fat absorption by inhibiting pancreatic lipase; the other is sibutramine, which is a specific inhibitor of the neurotransmitters norepinephrine, serotonin, and dopamine in the brain (very similar to some anti-depressants), therefore decreasing appetite. Rimonabant, a third drug, works via a specific blockade of the endocannabinoid system. It has been approved in Europe for the treatment of obesity but has not yet received approval in the United States or Canada due to safety concerns. Weight loss with these drugs is modest; over the longer term, average weight loss on orlistat is 2.9 kg, sibutramine is 4.2 kg and rimonabant is 4.7 kg. Orlistat and rimonabant lead to a reduced incidence of diabetes, and all drugs have some effect on cholesterol. There is little data on how these drugs affect the longer-term complications of obesity. It is common for weight loss drugs to be tried and if there is little or no benefit from them to discontinue treatment. A meta-analysis of randomized controlled trials by the Cochrane Collaboration concluded that in diabetic patients fluoxetine (Prozac), orlistat and sibutramine could achieve modest but significant weight loss over 12–57 weeks. The long-term health benefits remained unclear.
Obesity may also influence the choice of drugs used to treat diabetes. Metformin may lead to mild weight loss in comparison to sulfonylureas and insulin. It has been show to reduce the risk of cardiovascular disease in obese type 2 diabetics. The thiazolidinediones, on the other hand, may cause weight gain, but decrease central obesity and therefore can be used in obese diabetics.
Ephedrine (Ma Huang) is a stimulant effective for weight loss; however it is not recommended due to potential side effects.
Surgery for severe obesity is associated with long-term weight loss and decreased overall mortality. A controlled prospective study carried out in Sweden involving 4,047 people found a weight loss of between 14% and 25% at 10 years depending on the type of procedure performed and a 29% reduction in all cause mortality when compared to standard weight lose measures. A marked decrease in the risk of diabetes mellitus, cardiovascular disease and cancer has also been found after bariatric sugery. Weight loss is marked in the first few months after surgery and is sustained in the long term. In one study there was an unexplained increase in deaths from accidents and suicide but this did not outweigh the benefit in terms of disease prevention. When comparisons are made between the procedures gastric bypass surgery is found to be about twice as effective as banding procedures.
The effects of liposuction however are less well determined, with some small studies showing benefits and others showing none. and others
A clinical practice guideline by the US Preventive Services Task Force (USPSTF) concluded that the evidence is insufficient to recommend for or against routine behavioral counseling to promote a healthy diet in unselected patients in primary care settings, but that intensive behavioral dietary counseling is recommended in those with hyperlipidemia and other known risk factors for cardiovascular and diet-related chronic disease. Intensive counseling can be delivered by primary care clinicians or by referral to other specialists, such as nutritionists or dietitians.
The World Health Organization formally recognized the global nature of the obesity epidemic in 1997. As of 2005 the WHO estimates that at least 400 million adults (9.8%) are obese, with higher rates among women than men. The rate of obesity also increases with age at least up to 50 or 60 years old. Once considered a problem only of high-income countries, obesity rates are rising worldwide. These increases have been felt most dramatically in urban settings. The only remaining region of the world were obesity is not common is sub-Saharan Africa. South Pacific Many of the island nations of the South Pacific have very high rates of obesity. Nauru has the highest rates of obesity in the world (80%) followed by Tonga, the Federated States of Micronesia, and the Cook Islands. Being big has traditionally been associated with health, beauty, and status and many of these beliefs remain prevalent today.Australia Studies conducted in 2006 found that close to 52% of Australian women and up to 67% of Australian men aged 25 or over are overweight or obese.China Because the booming economy has increased average incomes, the population of China has since the 1980s taken up a more sedentary lifestyle and begun consuming more calorie-rich foods. From 1991 to 2004 the percentage of overweight or obese adults increased from 12.9% to 27.3%.India In India urbanization and modernization has been associated with obesity. As of 1999 in northern India 11% of urban women were found to be obese in contrast to 3.7% of rural women. Well women of high socioeconomic class had a rate of obesity of 10.4% as opposed to 0.9% in women of low socioeconomic class. With people moving into urban centers and wealth increasing, concerns about an obesity epidemic in India are growing.European Union Between the 1970s and the 2000s, rates of obesity in most European countries have increased. During the 1990s and 2000s the 27 countries making up the EU reported rates of obesity from 10–27% in men and from 10–38% in women.United Kingdom In the UK the rate of obesity has increased about fourfold over the last 25 years, reaching current levels of 22%.Mexico Mexico has the second-highest rate of obesity in the developed world, at 24.2% of the population.United States
Many countries and groups have published reports pertaining to obesity. In 1998 the first US Federal guidelines were published, titled "Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults: The Evidence Report". In 2006 the Canadian Obesity Network published the "Canadian Clinical Practice Guidelines (CPG) on the Management and Prevention of Obesity in Adults and Children". This is a comprehensive evidence-based guideline to address the management and prevention of overweight and obesity in adults and children. In 2004, the United Kingdom Royal College of Physicians, the Faculty of Public Health and the Royal College of Paediatrics and Child Health released the report "Storing up Problems", which highlighted the growing problem of obesity in the UK. The same year, the House of Commons Health Select Committee published its "most comprehensive inquiry [...] ever undertaken" into the impact of obesity on health and society in the UK and possible approaches to the problem. In 2006, the National Institute for Health and Clinical Excellence (NICE) issued a guideline on the diagnosis and management of obesity, as well as policy implications for non-healthcare organizations such as local councils. A 2007 report produced by Sir Derek Wanless for the King's Fund warned that unless further action was taken, obesity had the capacity to cripple the National Health Service financially.
Obesity has been recognized as a medical disorder at least since the time of Hippocrates when he stated that "Corpulence is not only a disease itself, but the harbinger of others". It was known to the Indian surgeon Sushruta (6th century BCE), who related obesity to diabetes and heart disorder. He recommended physical work to help cure it and its side effects. For most of human history mankind struggled with food scarcity. With the onset of the industrial revolution it was realized that the military and economic might of nations were dependent on both the body size and strength of their soldiers and workers. Increasing the average body mass index from underweight to the normal range playied a significant role in the development of industrialized societies. Height and weight thus both increased though the 19th century in the developed world. During the 20th century, as populations reached their genetic potential for height, weight began increasing much more than height, resulting in obesity. In the 1950s increasing wealth in the developed world decreased child mortality, but as body weight increased heart and kidney disease became more common. During this time period insurance companies realized the connection between weight and life expectancy and increased premiums for the obese.
Many cultures throughout history have viewed obesity as a flaw. The obesus or fat character in Greek comedy was a glutton and figure of mockery. During Christian times food was viewed as a gateway to the sins of sloth and lust. In modern Western culture, excess weight is often regarded as unattractive, and obesity is commonly associated with various negative stereotypes. All ages can face social stigmatization and may be targeted by bullies or shunned by their peers. In Western culture obesity is once again seen as a sign off a low socio-economic status. Obese people are less likely to be hired for a job and are less likely to be promoted. Obese people are also paid less than their non-obese counterparts for an equivalent job. Obese women on average make 6% less and obese men make 3% less.
The weight that is generally viewed as an ideal has become lower since the 1920s. The average height of Miss America pageant winners increased by 2% from 1922 to 1999, while their average weight decreased by 12%.
Amphetamines (marketed as Benzedrine) became popular for weight loss during the late 1930s. They worked primarily by suppressing appetite, and had other beneficial effects such as increased alertness. Use of amphetamines increased over the subsequent decades, culminating in the "rainbow pill" regime. This was a combination of multiple pills, all thought to help with weight loss, taken throughout the day. Typical regimens included stimulants, such as amphetamines and thyroid hormone, diuretics, digitalis, laxatives, and often a barbiturate to suppress the side effects of the stimulants. In 1967/1968 a number of deaths attributed to diet pills triggered a Senate investigation and the gradual implementation of greater restrictions on the market. This culminating in 1979 with the FDA banning the use of amphetamines, then the most effective of the diet drugs, in diet pills.
Meanwhile, phentermine had been FDA approved in 1959 and fenfluramine in 1973. The two were no more popular then other drugs until in 1992 a researcher reported that the two caused a 10% weight loss which was maintained for over two years. Fen-phen was born and rapidly became the most commonly prescribed diet medication. Dexfenfluramine (Redux) was developed in the mid-1990s as an alternative to fenfluramine with less side-effects, and received regulatory approval in 1996. However, this coincided with mounting evidence that the combination could cause valvular heart disease in up to 30% of those who had taken it, leading to withdrawal of Fen-phen and dexfenfluramine from the market in September 1997.
Ephedra was removed from the US market in 2004 over concerns that it raises blood pressure and could lead to strokes and death.
Obesity and its health effects create sizable economic costs. In 1998 in the US, the medical costs attributable to obesity were $78.5 billion USD, or 9.1% of all medical expenditures. Obesity prevention programs have been found to reduce the cost of treating obesity-related disease. Those reductions, however, are offset by medical costs incurred during the additional years of life gained. The authors therefore conclude that reducing obesity may improve the public's health, but it is unlikely to reduce overall health spending.
Obese workers have higher rates absenteeism from work and take more disability leave, thus increasing costs for employers and decreasing productivity. A study examining Duke University employees found that people with a BMI over 40 filed twice as many workers' compensation claims as those whose BMI was 18.5-24.9. They also had more than 12 times as many lost work days. The most common injuries in this group were due to falls and lifting, thus affecting the lower extremities, wrists or hands, and backs. The US state of Alabama Employees' Insurance Board approved a controversial plan to charge obese workers $25 per month if they do not take measures to reduce their weight and improve their health. These measures are set to start Jan. 2010 and apply to those with a BMI of greater than 35 kg/m2 who fail to make improvements in their health after one year.
Specific industries, such as the airline and food industries, have special concerns. Due to rising rates of obesity, airlines face higher fuel costs and pressures to increase seating width. In 2000, the extra weight of obese passengers cost airlines US$275 million. Costs for restaurants are increased by litigation accusing them of causing obesity. In 2005 the US Congress discussed legislation to prevent civil law suits against the food industry in relation to obesity; however it did not become law.
The first sculptural representations of the human body 20,000–35,000 years ago depict obese females. Some attribute the Venus figurines to the tendency to emphasize characteristics that portray fertility while others feel these could be actual representations of the people at the time. Corpulence is, however, absent in both Greek and Roman art, probably fitting with their ideals of moderation. This continued through much of Christian European history, with only those of low socioeconomic status being depicted as obese. During the Renaissance some of the upper class began flaunting their large size. This can be seen in portraits of Henry the VIII and Alessandro del Borro. Rubens (1577–1640) regularly depicted full-bodied women in his pictures, from which derives the term Rubenesque. These women, however, still maintained the "hourglass" shape with its relationship to fertility. During the 19th century, views on obesity changed in the Western world. After centuries of obesity being synonymous with wealth and social status, slimness began to be seen as the desirable standard.