Tuesday, February 5, 2013

Obesity in the Victorian Population


Obesity in the Victorian Population
Introduction
Obesity is defined as the excess body fat. In adults, the definition of obesity has been standardized internationally by the use of body mass index (BMI). This takes into account the differences that exist in the height and is calculated when the weight, measured in kgs, is divided by height, measured in meters squared. Normal body mass index has been estimated to 20 to 25. Therefore, individuals with body mass index from 25 to 29 are considered overweight; whereas those with greater than 30 are regarded as obese (Davin and Taylor 2009). The body mass percentile charts have also been used with overweight being defined as being greater than the 85th percentile in age, that of obesity being considered to be greater than the 97th percentile for age. Other measures that have been used in estimating the different aspects of fat distribution and overweight include measurement of the weight to hip ratio; skin-fold thickness; the percentage of the body fat; and visceral obesity which is generally measured by magnetic resonance imaging (MRI) or computer tomography (Oyetunji, 2012). However, it is important to note that the definition of childhood obesity has been difficult due to the fact that the body mass index has been changing and increasing with growth. Therefore, the use of adult’s definition can be misleading by underestimating the exact prevalence of childhood obesity. However, various researches have emerged in investigating obesity, both in adults and children as there is an increase in the prevalence of this disorder (Sanderson, Persky and Michie, 2010).  
Reasons for the increase in the rate of obesity
Proietto (2011) discusses the reasons for the increase in the rate of obesity in the world today. The author argues that the increase in the rate of obesity has been blamed on the increased access to high energy diet, coupled with the decrease in the rate of mandatory physical exercise. This means that the environment is what plays a major role in the increase in the prevalence of this disorder. Humans have Stone Age genes which were developed in a high energy expenditure setting. However, the current setting is one of food abundance and sedentary society. Most of the modern western lifestyle diseases such as obesity emanate from the lack of balance between the genes and the environment. However, there is an argument contrary to the environment playing the main role in obesity. The author suggests that not every person will become obese by being in what he refers to as an obesogenic environment. Different people will react differently to this environment. For instance, the effect of the environment on genetically lean persons is overweight and not becoming obesity.
Proietto (2011) suggests that prevention of obesity is achieved through a rise in the levels of as fat accumulates. He further posits that this is a typical negative feedback system. This means that there has to be genetic predisposition for the environment to play a role in obesity. This genetic predisposition is what impairs the negative feedback system. This means that when fed on the same kind of food, some young people will tend to add weight while others will not. This has been shown in twin and adoption studies. A range of weight gain has been shown to result from overfeeding monozygotic twins. Additionally, the level of weight gain in every pair of the twins has been shown to correlate. While genes are may be argued to account for a considerable amount of obesity, it is evident that monogenetic mutations that cause people to be severely obese, like deficiency in leptin or mutations of melanocortin-4 receptor, tend to be rare and thus cannot account for majority of the cases of obesity. Additionally, the present increase in the rates of obesity cannot be explained from the point of view of changes in genetic levels, due to the fact that mutations happen over a very long time frame. The developing evidence that majority of obesity might in nature be epigenetic may bring together the two clearly opposing perspectives.
Epigenetic obesity
Epigenetic modification refers to the change in gene expression which is permanent and results from environmental conditions which stimulate chemical changes, like promoter methylation and/or changes in the manner in which the DNA is packaged. A belief has persisted that epigenetic modifications happen chiefly in utero. Nevertheless, research evidence has emerged that early post-natal nutritional condition can also have an effect on epigenetic gene regulation. Rats predisposed to obesity became obese by consuming a diet rich in energy-rich for twelve weeks following weaning guard their increased weight following diet-induced weight loss. This was the case even following exposure to only diet low in fat (Proietto 2011).
Effectiveness of the present strategies
From the point of view that improper diet and lack of physical exercise are the main factors behind the increase in the prevalence of obesity, current treatment strategies are centered on these two factors (Poirier, Giles and Bray et al. 2006). However, articles such as the one written by Proietto (2011) suggest that encouragement of health diet and exercise are not likely to achieve long-term effects on obesity. Healthy diet and exercise for weight loss have been used for a long time in the treatment of obesity, but they are suggested to be ineffective. Proietto (2011) explains how weight loss following these treatment strategies encourages weight regain. He argues that following loss of weight, changes in energy expenditure as well as in the hormones that control hunger encourages regaining of weight. For instance, following loss of weight, there is an increase in the levels of ghrelin, and a subsequent decrease in the levels of leptin, holecystokinin and insulin. Additionally, there is conversion of the thyroid hormone T4 to the inactive reverse-T3 rather than T3, leading to the decrease in energy expenditure. There is the possibility that such physiological adaptations make it hard to maintain the loss of weight. More important, in case the regulatory mechanism is working in the individuals who are already obese, the treatment strategies which encourage use of health diet and physical exercise are less likely to have long term effects on weight loss.
In adults, body mass index is an important substitute for obesity due to the fact that it measures weight on the basis of height. Regardless the argument that body mass index does not provide any indication of the weight composition, or the distribution of weight, it is not particularly significant in surveys of thousands of individuals due to the fact that a high body mass index can logically be presumed to result from surplus fat mass. Nevertheless, care must be taken in the simplistic resumption that a high body mass index is the same as obesity when looking at the changes in a person in the long-term. This is because there is no much change in the height of adults over time. Thus, the change in body mass index lapses to a scale of change in the weight which renders little information on the changes in body composition. This is properly shown in the situation of the change in body mass index due to exercise. It is argued that the response to exercise is normally increases in lean body mass and skeletal muscle, particularly in the persons who are excessively inactive. As a matter of fact, most of the present exercise programs particularly focus on the increase in skeletal muscle mass in persons who are at risk. This is due to the fact that there is possession of manifold glucose uptake pathways by skeletal muscle. Such kind of exercises does not have any effect on body weight or body mass index (Green and Maiorana, 2012).
While Green and Maiorana (2012) provides some of the arguments proposed by some authors for the lack of effectiveness in the use of exercise as an intervention in obesity, the authors have also proposed a case for the effectiveness of exercise. They have argued that there is a decrease in cardiovascular risk due to exercise through mechanisms which depend on changes in body mass index. A number of studies have been carried out to show that exercise is related to a considerable decline in cardiovascular risk of about 30 percent. Meta-analyses also reveal the same kind of effectiveness achieved from cardiac rehabilitation programs based on exercise. Collectively, modification of common risk factors to cardiovascular problems was about 35.5 percent of exercise-mediated decrease in coronary risk. There is also a considerable effect of exercise on body mass index which accounted for approximately 6.8 percent of the total effectiveness of exercise-based intervention on coronary artery disorder.
According to Green and Maiorana (2012) “Fitness is a strong predictor of cardiovascular and all cause mortality and predicts risk much better than fatness” (p. 165). One of the major studies in this area is the Aerobics Center Longitudinal Study (ACLS). This study concerned exercise tests of cardiorespiratory fitness in 7080 women and 25 341men.  The results of the study indicated that a low fitness level granted the same kind of risk like smoking as well as higher risk compared to high levels of cholesterol and hypertension. It was also a strong factor in mortality compared to body mass index. Participants who were fit were found to have lower relative risk, even in the situation where they had several cardiovascular risk factors. Additionally, those who increased their level of fitness lowered their relative risk.  In the successive analysis of the Aerobics Center Longitudinal Study that looked at the impacts of fitness and fatness, obese individuals with preserved fitness were shown to have relatively lower risk compared to lean fit individuals, while lean unfit individuals had higher risk.
Exercise has also been shown to play an important role in the progression to diabetes in obese individuals (Plourde and Prud'homme 2012).  The Diabetes Prevention Program in the US is one of the programs that have looked at the role played by exercise-based intervention in the progression of diabetes in obese and individuals at risk. In a survey, there was random assignment of 3234 obese non-diabetic individuals with increased fasting blood glucose to get metformin, placebo, or an intensive program of lifestyle modification. This included about 150 minutes of exercise every week. There was a follow-up of about 2.8 years. On the completion of this period, compared with the placebo group, the occurrence of diabetes was lowered by 31 percent in the metformin group as well as 58percent in the lifestyle modification group. Lifestyle modification averted a case of diabetes in every seven individuals treated for three years. The positive effect as far as prevention or delay of diabetes is concerned persisted for as long as ten years. Nevertheless, between the metformin and the lifestyle modification groups, the disparity in body mass was somewhat modest. This indicated that benefits from exercise may be mediated by means which greatly depend on loss of weight. As a matter of fact, individuals who attained their exercise objectives but failed to achieve their weight loss objectives had a 44 percent decrease in the risk of diabetes compared to the participants in the placebo group. Thus, in people who are obese, exercise-based intervention are effective in reducing the chances of diabetes (Sanderson, Persky and Michie, 2010).  Exercise and lifestyle change which includes proper health diet have been proven to be effective in the management of obesity (Plourde and Prud'homme 2012). Thus, the importance of including exercise in the management of obesity cannot be underestimated.  In the case of obesity, storage of energy as fat is eventually connected to imbalance between intake (food) and expenditure (physical activity) of energy. Between contemporary Westerners and hunter gatherers, it has been approximated that the mean disparity in the expenditure of energy totals to the same as walking approximately 19 to 33km every day. The imbalance between the genes and the environment emerged as playing a major role in obesity. Thus, the role of exercise as an intervention strategy for diabetes cannot be ignored.
Intervention strategies and their physiological effects
Green and Maiorana (2012) have presented the case for exercise based intervention for obesity. According to Davin and Taylor (2009) physical exercise is an essential treatment strategy for obesity.
Most of the people who are obese manage to achieve weight loss in the short-term through the use of exercise-based intervention. It is important to note that loss of weight is one of the goals of treatment for people who are obese. Individuals who are obese, through physical exercise are able to loose weight and prevent further weight gain. Prevention of further weigh gain is an important short term effect of exercise-based intervention in obesity. However, maintaining physical exercise is one the key factors in the achievement of this goal.
The long term implication for exercise-based intervention strategies is the decrease in the risk of other disorders related to obesity. The primary goal of this intervention strategy is the reduction of the incidence of myocardial infarction, diabetes and stroke, as well as improving health and longevity. Obese individuals who are able to maintain physical exercise can maintain loss for more than one year (Burke and Wang, 2011).
However, according to Proietto (2011) the benefits of weight loss for people who are obese are not long-term. People only manage to loose weight for one to two years, and then regain it again over a longer term.  While weight loss through exercise-based intervention is achievable, it is noted that maintaining it is a challenge.
Bariatric surgery
Proietto (2011) has presented a case for bariatric surgery. Even Green and Maiorana (2012) have argued that bariatric surgery has a significant as well as evidence-based role in treating severe as well as recalcitrant obesity. Bariatric surgery offers an instance chance of loosing weight. The surgery can help one in loosing as much as 50 percent or even more of the excessive body weight.
Studies have shown the long-term effects of weight loss through the use of bariatric surgery, ranging from 13 percent to 31 percent even after ten of observation. This means that unlike dietary and exercise-based interventions, Bariatric surgery offers sustained loss of weight for people who are obese (Burke and Wang, 2011).  
While surgery has emerged as a more instant answer to the issue of obesity, some studies have suggested some risks associated with this intervention strategy. The surgery limits the amount of food one is able to consume comfortably, or decreased the absorption of calories and food, or both effects (Burke and Wang, 2011).

Conclusion
Obesity is increasing at a very high rate in the society today. Currently, obesity affects almost two thirds of the population bringing with its all its health implications. The major concern is the increase in cases of obesity among the children, adolescents and young adults. Most of the people suffering the effects of obesity are in these groups. This has led to the dire need for intervention to address this problem. It is important for policy makers in health care to use research-based evidence in the implementation of the most effective strategies to address the issue of obesity.











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