Obesity is excess body fat. It is usually defined by body mass index (BMI) which is individual’s weight (kg) divided by their squares of height (m) (Jebb, 2004; Eagle et al, 2004). At the same time, BMI was classified into four conditions. Firstly, when the BMI less than 18.5 kg/㎡is underweight. Secondly, 18.5 kg/㎡to less than 25.0 kg/㎡ belong to normal weight. Thirdly, overweight is 25.0 kg/㎡to less than 30.0 kg/㎡. Finally, exceeding 30.0 kg/㎡ is totally obese (Eagle et al, 2004). Other papers categorize more detailed in the part of obese, which sections three parts, such as, Grade I obesity (30.0 kg/㎡to less than 35.0 kg/㎡), Grade II obesity (35.0 kg/㎡to less than 40.0 kg/㎡) , extreme obesity or Grade III (40.0 kg/㎡or more) (Borrell and Samuel, 2014). Obesity has been defined as an epidemic by the International Task Force on Obesity and World Health Organization in the 21st century (Jiménez, 2011). For example, 65 per cent adults and 15 per cent children are overweight in America, and this data has not a decreasing trend (Jiménez, 2011).
In recent years, increasing obesity problems have emerged in developed countries and even in some city centers in developing countries (Jiménez, 2011). According to Rosin’s investigation (cited in Tomer, 2011), incidences of obesity in the United States are high and have been dramatically increasing over the past thirty years, although there are some steady trends recently (Rosin in Tomer, 2011). For instance, the percentage of the obese population in America rose twice from about 13.95 per cent (in 1976) to 29.57 per cent (in 2000), and this figure is continuing to grow (ibid). However, rates of obesity are not only in America; it is growing in all of the world; even in Japan which has one of the lowest rates in the world (Bleich et al in Tomer, 2011; Delpeuch et al in Tomer, 2011).
This essay consists of four sections, including introduction, effects of obesity, causes of obesity and conclusion. It will focus on the effects and causes of obesity. On the one hand, it analyses that two aspects of negative impacts which are death rate and chronic conditions are caused by obesity. On the other hand, this article discusses the complex reasons of obesity, which are classified as the congenital factors and acquired factors respectively.
Effects of obesity
Nowadays, increasingly, people have been focused on obesity bringing to serious impacts of health. The effects of obesity can be classified into two parts. One is the relationship of obesity and death rates; another is the relationship of obesity and chronic conditions (Tomer, 2011). It is claimed that the mortality risk and premature deaths are influenced by obesity epidemic amid American adults (Borrell and Samuel, 2014). Some data indicates 300,000 premature deaths per year are connected with obesity in America (Tomer, 2011). Furthermore, there is a school of thought that obesity is a main risk factor for many chronic conditions. There are known as the Western disease; including type 2 diabetes, cardiovascular disease (CVD), certain types of cancer, hypertension and hypercholesterolemia (Rosin in Tomer, 2011). Let us now discuss two aspects of negative impacts.
The relationship of Death Rate and Obesity
There is a possibility that obesity will decrease individual’s lifespan by 3 to 13 years on average (Jiménez, 2011). Mortality might be greater and greater when the obesity phenomenon becomes serious in the future. Over the past five decades, obesity has been related to morbidity or all-cause mortality which means death rates caused by diseases, except for taking dugs and suicide, in the United States and elsewhere (Borrell and Samuel, 2014). Firstly, compared with a normal weight individual, obese adults have at least 20 per cent higher rate of dying for all-cause (Borrell and Samuel, 2014). Further, an obese individual who is Grade I obesity will die earlier at least 1.6 years than a normal-weight individual considering all causes (ibid). At the same time, this figure for Grades II and III obesity person are 3.7 years (ibid).
Secondly, base on Borrell’s research data, when individual who is overweight and obese (regardless of the grade) get the CVD disease, it can be found out that these individuals’ dying rate will be significantly higher than individuals who have normal weight (Borrell and Samuel, 2014). After studied individuals who were different race and have different education backgrounds, the research acquired it one result that obese individuals might have a shorter life than normal-weight individuals for CVD-specific mortality and the same phenomenon could exist in different ages people (ibid).
In addition, the dangerous situations were the worst in obese adults whose ages are between 45 and 64 for all-cause and CVD-specific mortality (Borrell and Samuel, 2014). It means that Grades II and III obese adults aged 45 to 64 years have significantly higher death rates than people who have normal weight. These higher death rates lead to among Grades II and III obese adults (45 to 64 years old) early death by at least 7 years (ibid). Through a great many prospective studies, it is widely accepted that obesity contributes to premature death. Apart from, obesity has other disadvantages to individuals.
The relationship of Chronic Conditions
Obesity might raise some diseases’ hazard and the biggest main risk is cardiovascular disease (Jebb, 2004). There are these who maintain that, in public health terms, the largest burden of disease is morbidity which is related with obesity and almost every organ of human body is caused by obesity (Jebb, 2004). Jebb (2004) states that ‘It effects include metabolic syndrome (type 2 diabetes, hypertension and hyperlipidemia), and mechanical disorders (e.g. osteoarthritis, respiratory problems, sleep apnoea) and psychosocial disorders’ (Jebb, 2004). Other scholar has a similar view that it is a significant problem that obesity is not only one of the endocrine-metabolic conditions but also is a beginning of a series of diseases including type 2 diabetes mellitus, cardiovascular diseases, metabolic syndrome and some types of cancer in public health (Jiménez, 2011). Let us detail that those relationships between obesity and the following diseases.
Firstly, there is an extremely close relationship of type 2 diabetes and obesity. Diabetes belongs to metabolic syndrome, which causes the factors of atherosclerotic disease (Jebb, 2004). Further, the development and severity of this kind of disease is depending on weight increase (ibid), thus obesity is an important element factor. For example, women whose BMI is 25 kg/㎡ lead to the probability of diabetes is just five-fold, if the BMI is over 35 kg/㎡, the probability will increased to more than 40-fold (Jebb, 2004). Furthermore, the probability of diabetes still depends on different body shapes, such as, apple-shaped, pear-shaped, if women have a similar BMI. Jebb found apple-shaped women who have a large waist are higher diabetes risk than pear-shaped women who have excess fat on the thighs and hips (Jebb, 2004).
Secondly, cardiovascular disease is also linked with obesity or weight increase. The Nurses’ Health Study suggests that BMI is associated with cardiovascular disease (Jebb, 2004). Compared with the risk of CVD at BMI less than 21.5, the risk rose from BMI 22-23 and doubled at 25-28.9 and more than three times higher when the BMI reached at above 29 (ibid).
Thirdly, the recent year have a growing recognition which is the relationship between obesity and increased risk of most types of cancer, with the exception of lung cancer, postmenopausal breast cancer, colon and kidney cancer (Jebb, 2004). At the same time, it is estimated to ascribe 20 per cent of cancer deaths in women to obesity (ibid). It seems that the link between cancer and obesity is confirmed.
To sum up, obesity is a serious global problem. To some extent, it became a killer to make human beings die prematurely. In recent years, people have begun to pay close attention to this topic. But what caused the obesity is the key point, which is worth us to explore: the next section will analyze some important factors that lead to obesity.
Causes of obesity
The causes of obesity are extremely complex. A huge number of research indicate that the reason of obesity is not a single result. People are obese because of the complex interaction between genes and the unique personal habits (Eagle et al, 2004; Jiménez, 2011; Tomer, 2011). Firstly, genes are not only crucial factor for obesity, but the environment also plays an important role (ibid). At the same time, genes will be changed with parental unique lifestyle and their surrounding (Eagle et al 2004; Jiménez, 2011). Secondly, the unique personal habits involve numerous aspects, such as, diet, choice habit, sedentary lifestyle and other social factors (Tomer, 2011). It seems that the causes of obesity are complex and constantly changing. To sum up, these reasons are divided into two major categories, congenital and acquired factors. This section will detail how two kinds of factors can make individuals obese.
There is no doubt that genes are one of the causes for obesity. Nowadays, ‘sufficiently solid scientific evidence’ provides that genes are involved in the development of obesity (Jiménez, 2011). It is determined that individuals’ metabolism, detoxification and production of hormones could increase their weight and make them obese (Tomer, 2011). For instance, some small parts of obese individuals owes to genes which lead to some clinical syndrome. Obesity’s monogenic reasons include mutations in the leptin gene and its receptor, or the melanocortin system. Other genetic syndromes are a common element of the phenotype. However, these occupy only small parts (Jebb, 2004). At the same time, heritability studies indicate that genetic factor is only influenced approximately a third of the variance of BMI (ibid).
Therefore, it is claimed that genes are just potential inducers for obesity (Jiménez, 2011). On the other hand, even some scholars maintain that obesity is the result mixed up with certain genes and the environment. Genetic changes produce a new trend that obesity is a result of the interaction between genes and environment (Jiménez, 2011). It means that the new gene will be decided jointly by the previous generation of genes and environments. Furthermore, a mass of other candidate genes have been associated with obesity. For example, food preferences or exercise habits (Jebb, 2004).
Compared with congenital factors, acquired factors are more influenced for obesity. It is reflected in the people’s diet, behavior patterns and many other aspects (Eagle et al, 2004; Jiménez, 2011; Tomer, 2011). Jiménez’s view is that due to a long time energy’s accumulation which is energy intake exceeds people needs, there are some obese people. Two crucial behaviors are food intake and taking exercise resulted in obesity (Jiménez, 2011). Hyman (cited in Tomer, 2011) states that there are three dietary reasons producing obesity, including ‘diet high in refined, processed carbohydrates’, ‘diet high in bad fats’ and ‘diet low in fiber’ (Hyman in Tomer, 2011).
However, Brownel (cited in Tomer, 2011) concluded that powerful forces of society and culture are the root of the obesity problem, because it can promote individuals selecting high energy diet and a sedentary lifestyle (Brownel et al in Tomer, 2011). Over the past three decades, the obesity issue was aggravated by this kind of environment (Brownel et al in Tomer, 2011). It is worth noting, these effects will not make everyone change their eating habits; it depends on different people. Apart from genes, if someone understands nutrition very well, they may escape the effect of environment. Nevertheless, unfortunately a great many people are vulnerable to the toxic environment impact (Brownel et al in Tomer, 2011).
This next section will minutely explain the acquired factors of obesity, including eating habits, less activity and watching advertisements on television. Owing to some poor eating habits, there were so many obese people (McLannahan and Clifton, 2008: p28). In the first place, different foods provide different extent energy, so that intake energy more than their need lead to obesity. For example, when individuals eat more than their need in their daily life, they will become fatter (McLannahan and Clifton, 2008: p29-31). It demonstrates that excess food’s intake caused excess body weight (McLannahan and Clifton, 2008: p29). In the second place, energy-dense diet is an important reason for make people obese. Energy-dense diets are high in fat, high in added sugars and low in fruit and vegetables and this kind of diet could enhance the probability of obesity (Jebb, 2004).
Fast foods are typical energy dense diets, and these are acknowledged to be a risk factor for obesity (Niemeier et al in Musaiger et al, 2014). Musaiger’s research showed that as a result of the high consumption of fast food, there was an increase trend about obesity (Musaiger et al, 2014). At the same time, a report was carried out by Gortmaker (cited in Musaiger et al, 2014), a high consumption of soft drinks was proved to be a reason for obesity.
It is concluded that ‘sugary beverages are less satiating than solid food containing similar calorie values’, therefore it contributes to acquire more energy (Gortmaker et al in Musaiger et al, 2014). In addition, there is a school of thought that eating more fruit and vegetables are beneficial to decrease the probability of obesity (Musaiger et al, 2014). For instance, in the United States, 12-year old boys and 11-year-old girls consumed any fruits and vegetable occupied 56.1 per cent and 65.5 per cent respectively (Eagle et al, 2004). It may be explained that nearly half children do not eat any fruits and vegetable, and it boosts the number of obese children.
Another important reason is lack of activity. Nowadays, modern people living in developed societies do not take more exercise than their ancestor (McLannahan and Clifton, 2008: p28). It is possible lead to obesity. Hyman (cited in Tomer, 2011) provides that a sedentary pattern can make weight gaining, through the lower metabolic rates (Hyman in Tomer, 2011). Moreover, some evidence indicates that the awareness of the innate appetite control system can be strengthened by high levels of physical activity. In the mean time, it is easier to automatically make energy intake and energy needs balance (Jebb, 2004). This is a key issue that ‘increases in obesity can not be simply attributed to over-eating or inadequate activity, rather it represents a failure of the homeostatic mechanisms to precisely match energy intake to the body’s energy needs’ (Jebb, 2004).
Furthermore, exercise’s levels are also important. People whether willing to do exercise is a main factor of energy needs (Jebb, 2004). For example, if a person who is a white-collar worker has a sedentary life, driving a car commuting and not seeking leisure activity, their basal metabolic rate may be used just 30 per cent (Jebb, 2004). On the contrary, a generally active adult may expend about 60 per cent and a particular active sportsman can consume double her or him basal energy needs (Jebb, 2004). It can be seen that doing more activity contributes to consume more energy, particularly helping to maintain insulin sensitivity and reduce the risk of obesity.
Furthermore, in the recent year, people spend more time on internet and watching television. Therefore, high-tech environment brings some influences to make people obese. The Henry J Kaiser Family Foundation indicates that adverts on television have effects on childhood obesity levels (Musaiger et al, 2014). At the same time, according to the American Psychological Association’s report, children less than 8 year olds do not distinguish the difference between adverts and reality (Musaiger et al, 2014). Through displaying some advertisements which some stars eating delicious foods makes a condition reflection, so that people who watches advertisements may eat more foods, and it causes an increase of intake energy, especially if people repeatedly watches these advertisements on television (Eagle et al, 2004).
Actually, is utilizes the changeless relationship of stimulus and response in human’s brain, according to Classical Conditioning theory (Eagle et al, 2004). When people watches television, it equivalently irritate people’ awareness that need eating snack or meals. Thus watching television is a way to cause intake more energy and make people obesity. Further, advertisements on television not only boost people eating but also have negative impacts on food choices of viewers. To some extent, it caused people preferring to choose higher fat and higher energy foods (Eagle et al, 2004). To sum up, watching television leads to people become obesity.
As discussed above, there is a dramatic rise about obesity in many countries nowadays, due to the complex interaction of a variety of reasons, divided to congenital causes and acquired factors (Wright, 2012). Moreover, obesity has many negative impacts on human health. It represents in higher death rate and many chronic conditions. The purpose of this essay is make people understand that these diseases have produced seriously harm to people’s health, and through explaining causes of obesity make people improve obesity problem. To be specific, the causes which lead to obesity are extraordinary complex, divided into congenital and acquired factors. There is no doubt that the congenital factor is genes result in obesity’s development. Furthermore, the acquired factors involved many aspects, including diet, life behavior patterns and high-tech environment.
This essay particularly has explained that three factors, such as eating habits, physical activity and watching advertisements on television, resulted in obesity. On the other hand, obesity is not only endocrine-metabolic disease, but also it is many other diseases’ start. For instance, some serious risks which are the premature death and morbidity of chronic conditions are caused by obesity. Firstly, about premature death, this essay used some data which compared different lifespan of different extent obese people and normal weight people, particularly middle aged and elderly people are particularly serious. In addition, in the part of chronic disease, this essay has analysed the type 2 diabetes, cardiovascular diseases and some types of cancer were produced by obesity. To sum up, obesity is a global problem. As a result of many complex reasons, there are increasing people became obesity. At the same time, obesity boosts rate of premature death and morbidity of chronic conditions.
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