Definition of Obesity - Paper Example

The term obesity can be defined as a state of being excessively overweight. It can also be defined as a condition characterized by the accumulation of excess fats in the adipose tissue, to the point that a persons health is compromised. There are various ways in which an individuals health relative to their weight can be categorized, but the commonly used approach is the body mass index. Body Mass Index (BMI) is the instrument used to assess the association between weight and stature in people of all ages. BMI is calculated by dividing an individuals body weight in kilograms by his or her square of the height in meters. That is, BMI = Weight (Kg)/Height (m) 2. If a persons BMI is less than 18.5, he or she is termed underweight. If the BMI is in the range of 18.5 and 25, a person is said to be within the normal range. If the BMI is in the range of 25.0 and 30, a person falls within the overweight range. Lastly, if an individual has a BMI of more than 30.0, he or she falls in obese range .

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Obesity is further categorized into 3 grades. Grade 1 obesity has a BMI of between 30 and 35; grade 2 has a BMI of between 35 and 40 while grade 3 has a BMI of 40 or higher . Grade 3 obesity is described as extreme or severe obesity. Some of the causes of obesity include excessive food intake, sedentary lifestyle, genetic factors, or a combination of these factors. There is no proof to back the assertion that obese individuals eat little but gain weight due to slow metabolic rates.

BMI use comes with some limitations. For instance, it is a surrogate measure of body fatness because it measures body weight instead of the bodys excess fat content. It does not also take into account factors which may affect the relationship between BMI and body fat, such as age, ethnic backgrounds, muscle mass, and sex. Lastly, there is no clear distinction between excess fat, bones mass, or muscle mass in this measure and does not also show the distribution of fat among people. Despite these limitations, the use of BMI measurements in the evaluation of underweight, overweight and obesity in adults has been accepted in the health sector. However, its application in children and adolescents is different because BMI of children and adults undergo significant changes with age during these growth phases. Because of limitation of its use in children, the World Health Organization (WHO) recommended that a growth reference is used in the measurement of BMI in young children.

Worldwide Impact

Obesity is a global epidemic that affects more than 600 million adults. In 2014, more than 1.9 billion people were reported to be overweight by the WHO. Additionally, it was also reported that 13% of the global population were obese in the same year. In the same year, 39% of adults above the age of 18 were found to be overweight. The prevalence of obesity has doubled between 1980 and 2014. Worldwide statistics show that overweight and obesity are the fifth leading cause of death, with deaths associated with the condition increasing in children and adults. Overweight and obesity are associated with more deaths globally compared to underweight. For instance, 65% of the people live in countries where overweight and obesity causes more deaths than underweight. These include countries having high incomes and most countries with middle income.

Obesity continues to receive stigmatization in most parts of the modern world, especially the Western world. In the past, it was associated with wealth and fertility. This notion still exists in some regions of the world. Even though obesity is a common condition, it has not received clinical and public health attention it deserves in most countries around the world. This condition has been found to lead to various comorbidities. For instance, elevated BMI levels is a risk non-communicable diseases. These diseases include heart diseases and stroke, which are the leading global causes of death. Moreover, obesity has been found to lead to diabetes and certain cancers. The risk for these diseases increases with increase in BMI. Apart from causing diseases, childhood obesity leads to increased chances of obesity early death, and disability in adulthood. Additionally, childhood obesity has been associated with breathing difficulties, elevated risk of fractures, high blood pressure, and insulin resistance. The health consequences of obesity are of profound importance for the affected people. Its morbidity has also been found to be economically damaging for society.

Metabolically Healthy Obese

Within the obese population, a subgroup which do not show the common metabolic impairments associated with obesity has been identified. This group of individuals is thought to be at a lower risk of developing obesity-related complications, and are referred to Metabolically Healthy Obese (MHO) . MOH was formerly described as a subgroup of obese people lacking type 2 diabetes and hypertension. Apart from body fat content and resistance to insulin, there are other metabolic risk factors that are important in the description of metabolically healthy obesity in view of their well-established link to the risk. They include lipid profiles, physical fitness, inflammation, and blood pressure.

There is no universally accepted criteria for defining putative MHO. However, currently existing definitions agree that the patient must be obese and lack metabolic impairments or metabolic syndromes. Some researchers are of the view that MHO is manifested by obesity devoid of metabolic diseases, such as type 2 diabetes, dyslipidaemia, and high blood pressure. MHO people also have normal blood glucose, lower inflammatory markers than obese individuals, normal or near-normal lipid profile, and normal blood pressure. Other researchers argue that MHO is a condition characterized by preserved insulin sensitivity. MHO individuals also show lower amounts of visceral adipose tissue, small adipose cells, and decreased inflammatory profile compared to metabolically impair obese people.

Prevalence

In the general population, the prevalence of MHO is estimated to be 8.6%. Among the obese individuals, the prevalence of MHO is between 20% and 30%. The percentages of metabolically healthy people who fall in the overweight and obese categories are 87.1 % and 55.5 % respectively. In the obese category, 58.8%, 40%, and 38.7% of individuals are grade 1, grade 2, and grade 3 obese respectively. In overweight and obese categories, people who are metabolically healthy have been found to be younger, female, are more likely to engage in physical exercise, are less likely to drink or to be smokers when compared to metabolically unhealthy individuals. Among the underweight and normal weight individuals, metabolically unhealthy persons are older, blue collar employees, male, and likely to be heavy smokers and drinkers compared with those who are metabolically healthy. In the normal weight group, a higher percentage of metabolically unhealthy people have also been found to have a sedentary lifestyle than their metabolically healthy counterparts in the normal weight group .

Implications of Metabolically Healthy Obese

Studies on the clinical outcomes of MHO have produced mixed results. For instance, some studies have shown that MHO individuals have a lower risk of cardiovascular disease (CVD) than individuals metabolically at-risk obese individuals while other studies have reported no differences between MHO individuals and normal-weight ones in CVD risks. Other studies have reported that MHO have a borderline significant increase in risk of developing diabetes. Clinical outcomes in MHO may be influenced by differences in fitness, body composition, and inflammatory profiles. MHO individuals have been reported to have better fitness than metabolically at-risk obese individuals. They have also been found to have more favourable inflammatory profiles and less fat than individuals with metabolically abnormal individuals.

Insulin Resistance

The term Syndrome X, introduced by Gerald Reaven in 1988, refers to a collection of independent, coronary heart disease (CHD) risk factors in the same person. Some of the risk factors included in syndrome X include failure of insulin to maximally stimulate transportation of glucose into the bodys cell, high blood pressure, elevated triglyceride levels, and low high-density lipoprotein cholesterol (HDL). Other terms used in place of syndrome X include insulin resistance syndrome and metabolic syndrome. Even though obesity has been associated with insulin resistance, many individuals who have normal weight or are overweight have shown features of metabolic syndrome. Insulin resistance is a major risk factor for Type 2 Diabetes.

The association between obesity, elevated triglyceride levels, and insulin resistance is complex. Studies have found that the presence of visceral adipocytes in the obese is responsible for mobilization of large quantities of free fatty acids and glycerol. The availability of these adipocytes at the hepatic level also stimulates synthesis of triglycerides and promotes gluconeogenesis, metabolic processes that leads to production of glucose from non-carbohydrate carbon substrates. Elevated levels of free fatty acids, at the skeletal muscle level, also promotes insulin resistance leading to suppressed uptake of the insulin-mediated glucose. Additionally, increased amounts of free fatty acids results in decreased insulin sensitivity at the adipocyte level, where insulin usually has an inhibitory effect on the breakdown of lipids to fatty acids (or lipolysis).

Underlying Mechanisms That Explain the Existence of MHO

Subclinical Inflammation

Inflammation promotes insulin resistance. The increased metabolic risk for type 2 diabetes (T2DM), fatty liver disease, and cardiovascular disease is associated closely with the inflammation of the greater adipose tissue. Obese adults, on the other hand, with no adipose tissue have a reduced metabolic risk. Subclinical inflation, as research evidence suggest, may be an unrevealed causal mechanism that decides whether an individual is MHO or not. Subclinical inflammation has a close association with insulin resistance, and CRP is used in the prediction of vascular inflammation, cardiovascular disease, and metabolic syndrome. The proposal of CRP as a tool for screening metabolic syndrome in youths is because of the strong relationship between the CRP circulating levels and the anthropometric markers and body composition. The concept of more favorable inflammatory state in comparison with none- MHO subjects is supported by the MHO phenotype associated with low levels of complement component 3, alpha necrosis tumor factor (TNF-a), interleukin 6 (IL-6), and diminishing number of white blood cells.

Anti-inflammatory adipokines such as IL-4, IL-10, IL-13, IL-1 receptor antagonist, and transforming growth factor are many in the adipose tissues of lean individuals. Adipose tissue of the obese, on the other hand, dictates pro-inflammatory adipokines discharge which includes CC-chemokine ligand 2, retinol-binding protein 4, CXC-chemokine ligand 5, Angiopoietin-like protein 2, leptin, lipocalin 2, resistin, TNF-a, IL-6, IL-18, and nicotinamidephosphoribosyltransferase.

Free fatty acids (FFA) and the activation status and the count of peripheral leukocytes are the other general inflammation markers of the adipose tissue. Therefore, obese patients who have T2DM are known to depict elevated levels of IL-6, FFA and glycerol and a higher number of peripheral white blood cells than non-diabetic obese patients. Unhealthy obese subjects with no metabolic disease possess a low insulin resistance degree and similar markers of adipose tissue inflammation as those non-obese, having no macrophages infiltration and TNF-a and IL-6 value elevation expression in...