EVALUACIÓN FINANCIERA

The aetiology of obesity is very complex and has perplexed researchers since it was first described.²³ It is affected generally by factors such as genetics and environment, in addition to social, physiological and psychological factors.²³ This suggests that environmental and socioeconomic factors are probably the main causes of the global risk in obesity.^23,27

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Obesity increases with increasing age but is generally higher among middle aged group.^16,55 Probably, it starts early in life and varies from infancy to early childhood, adolescent and early adulthood.⁶

It is found 3.3 times higher in females compared to males according to Raina et al in India.¹⁵ Among African – Americans and Mexican – Americans the prevalence is nearly twice as high in women than in men according to Aneja et al in US.²⁸ Aldair (2005) stated that in South Africa, one in every 3 men and more than half the female population are obese.⁵⁶ More than one-third of African women and a quarter of African men are estimated to be overweight, and WHO predicts, that will rise to 40% and 30% respectively in the next 10 years (WHO 2005).⁷

In the Durban study, a prevalence of 3.7% in men and 22.6% in women was observed. Rates of 8.3% for men and 35.7% for women have also been reported from Nigeria.⁹ Olatunbosun in western Nigeria reported prevalence of 42% for women compared to 15% for the male population as either overweight or obese.⁶⁰ Puepet et al reported prevalence of 19.4% in males and 23.5% in females among urban Nigerians in Jos.⁶¹ However He et al in Shanghai reported a slightly higher prevalence of general obesity based on BMI among men compared to the women (46.4% versus 43.6%), but the rate was higher in women than in men for central obesity and morbid obesity.⁶² Obesity and central type is more in females than males.⁸ Amole et al reported that women were significantly more sedentary than men which accounted for higher obesity prevalence rate compared to men.⁶³

In the western countries, rates have been greatest in African – American women, followed by Hispanic women, then white women, according to the data from the NHANES data.³⁸ It is also likely that genetic or molecular factors or environmental factors contribute to these racial differences, including health – related behaviours or lifestyles and economical disadvantages.³⁸

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Strigel – Moore et al reported that black women when compared to white women experienced less social pressure about their weight resulting in higher prevalence of obesity among black women.⁵⁶ Social stigma against obesity and the pressure to remain lean in some developed countries has probably helped limit obesity to some extent.²⁷ However, this psychosocial attitude toward obesity is not seen in many developing countries.²⁷ Studies in African Americans show a lack of social pressure to be thin and reduced stigma toward obesity by the individual and community.²⁷ For example, Gambian populations were reported to be more obese tolerant (acceptance of obese body size as normal) than African-American and much more tolerant than white Americans.²⁷ A study among nurses in Akwa-ibom observed that most obese nurses never perceived themselves as being obese but see their weight as signs of good living.⁵⁶ These findings also agreed with the work of Ntui (2000), who reported that certain societies thought and still think that fatness in females is an index of beauty.⁵⁶

Low levels of activity (sedentary life style) and sedentary jobs resulting in fewer calories used than consumed, contribute to the high prevalence of obesity.7,13,16,17,28 Hours spent browsing internet, playing video games and watching television at leisure, in addition to many labour saving devices of the modern lifestyle, such as cars, elevators, and remote controls promote a sedentary lifestyle.^7,23 In addition, diets like pre-packed foods, soft drinks and fast food restaurants which tend to have high fat, sugar and calories have become more accessible to people.^7,23 Amole et al in Ogbomoso reported that obesity was significantly associated with high energy foods and sedentary lifestyle.⁶²

Obesity is more in urban than rural areas.^8,23,27 This was demonstrated by Asya among Omani adults, Al-Othaimeen among Saudi adults and most studies in both developing and developed countries.^8,23,27 Most people who belong to low socioeconomic status and living in rural area of

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the developing countries are lean.²⁷ However, when these people migrate from rural areas to large metropolitan cities, they quickly acquire risk factors associated with urbanization despite remaining in the same socioeconomic status as the previous habitat.²⁷ Most literature showed that in spite of rampant poverty in urban areas, access to cheap foods with a high content of fats and sugar among the urban poor is easier than among the rural population.^25,59 Some studies have shown that recent migrants to cities tend to have a higher BMI than rural residents and those with longer urban environmental exposure, with increasing urbanization, there might be a shift of the obesity burden to section of the poor urban population who may not have the knowledge or financial resources to adopt healthier lifestyles.²⁵

Studies in developed countries show an inverse (negative) relationship between education and obesity.^27,31 The lower the education or social class, the higher the prevalence of obesity.^27,31 However, in developing societies, a strong positive relationship often exists between socioeconomic status which has a relationship with education and obesity among men, women and children.³¹ Kamadjeu et al among urban adult population of Cameroon reported a positive association between obesity and duration of education, as measured by the number of year of schooling in both gender when obesity was defined by BMI or WC.³¹ Al-Tawil et al in Iraq and voster in South Africa reported no relationship between socioeconomic or educational level and obesity.²⁵ Hajian-Tilaki et al in Iran on the other hand reported a significant negative association between education and generalized obesity in men and women, with a clear dose-response from high school to university level compared with illiterate and primary in both sexes.⁶⁴ Studies from developed countries and in a few developing countries demonstrate that the burden of obesity is shifting toward low educated and low socioeconomic status.^55,64 In Nigeria, its association with wealth and affluence has raised the prevalence to levels that now constitute an epidemic threat.²⁵

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Higher socioeconomic status in developing countries is characterized by a westernization of lifestyle, including reduced physical activity, more sedentary life and adoption of high energy and high fat diets; all of which may lead to an increase in obesity.^27,31,35 However, it is also possible that if westernization of diet and reduced physical activity becomes more general in developing country population, the familiar inverse association of obesity with socioeconomic status will emerge.³¹

Reproduction is thought to play a role in overweight in developing countries as it does in developed ones.⁶⁵ Kim et al reported a positive relationship between parity and overweight among women of developed countries, whereas in developing countries parity-related overweight is more among wealthy women.⁶⁵ The research was for women of reproductive age (15-49 years) from cross-sectional nationally representative surveys conducted in 50 low and middle income countries in five regions around the world.⁶⁵ Ertem et al also reported a positive correlation between parity number, and body weight, BMI and hip circumference.⁶⁶

Obesity tends to run in families suggesting a genetic cause.^7,55 Scientists are unclear about which genes affect human obesity.⁷ Families also share diet and lifestyle habits that may contribute to obesity. More than 250 genes that may play a role in obesity have been identified in mice and human. The cause of obesity is believed to be complicated and most likely involves the interaction of multiple genes with lifestyle factors.⁷

Certain drugs such as oral contraceptives, steroids, antidepressants, and some medications for psychiatric conditions cause weight gain.^7,55 Psychological and metabolic diseases such as hypothyroidism, and Cushing’s syndrome may be a cause of overweight and obesity.⁵⁵

In the study of Senekal, Sten and Nel on 2100 people, smoking was not associated with obesity.⁵⁵ Another study carried out in US on 16587 people showed that smoking cessation was associated

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with 1.98cm gain in waist measurement.⁵⁵ Sasaki et al reported that smoking, heavy alcohol consumption and overweight or obesity in additive manner are important determinants of Plasma PAI-1 levels (Plasma plasminogen activator inhibitor-1) which contributes to the pathogenesis of atherosclerosis and is a predictor of Ischaemic heart disease.^67,68

For any given individual, obesity is a multi-factorial trait influenced by both genetic and environmental factors.⁷