The worldwide prevalence of obesity and its metabolic complications have increased substantially in recent decades. According to the World Health Organization, the global prevalence of obesity has nearly doubled between 1980 and 2008. Complications of obesity is well known and so severe that every obese should try to withdraw the excess weight as early as possible.
Relation between body weight and mortality
A very high degree of obesity seems to be linked to higher mortality rates.
There is a strong association between obesity and type 2 diabetes mellitus, in both genders and all ethnic groups, weight gain appears to precede the development of diabetes. Insulin resistance is an integral feature of metabolic syndrome and is a major predictor of the development of type 2 diabetes. It has long been recognized that obesity is associated with type 2 diabetes, and the major basis for this link is the ability of obesity to induce insulin resistance.
Hypertension is strongly linked to obesity. The Swedish Obesity Study showed hypertension to be present at baseline in 44 –51% of obese subjects. Not only is obesity linked with hypertension, but weight loss in obese subjects is associated with a decline in blood pressure. The anti-hypertensive effect of weight loss is independent of race or gender. Furthermore, chronic obesity reduces the efficacy of anti-hypertensive medication.
Obesity is associated with an unfavourable lipid profile. In a comprehensive meta-analysis, weight loss of 1 kg decreased serum total cholesterol by 0.05 mmol/l and LDL cholesterol by 0.02 mmol/l, and increased HDL cholesterol by 0.009mmol/l.
Coronary artery disease
An increased risk of coronary artery disease in the overweight was apparent.
The relationship between obesity and heart failure is complex. In the Framingham Study, almost 6000 individuals without a history of heart failure (mean age 55 years) were followed for a mean of 14 years. The risk of developing heart failure was twofold higher in obese individuals, compared with subjects with a normal body-mass index. It was estimated that 11% of the cases of heart failure in men and 14% in women could be attributed to obesity alone. Individuals with obesity have a form of cardiomyopathy attributed to chronic volume overload characterized by left ventricular dilatation, increased left ventricular wall stress and compensatory left ventricular hypertrophy. Most studies have reported abnormal diastolic function, without abnormal systolic function.
As noted above, obesity is linked to hypertension, coronary artery disease, diabetes mellitus, left ventricular hypertrophy, left atrial enlargement and CHF. Hypertension, left atrial enlargement and congestive heart failure are all strongly linked to atrial fibrillation. clear relationship between AF and obesity has only recently been established.
Obesity is linked to an increased risk of stroke in both men and women.
Obstructive sleep apnea
Obesity is a major risk factor for obstructive sleep apnea (OSA). Over 75% of patients with OSA are reported to be 4120% of ideal body weight.74A neck circumference 417 inches, which is correlated with obesity, has also been highly correlated with OSA, In addition, mild-to-moderate weight loss can substantially improve sleep apnea.
The prevalence of asthma is increased in overweight subjects, and obese or overweight subjects account for 75% of emergency department visits for asthma. Longitudinal studies indicate that obesity antedates asthma, and that the relative risk of incident asthma increases with increasing obesity. In addition, morbidly obese asthmatic subjects studied after weight loss demonstrate decreased severity of asthma symptoms. Obesity also appears to be a risk factor for airway hyperresponsiveness. The relationship between obesity and asthma is underlined by the finding that obesity is a strong predictor of the persistence of childhood asthma into adolescence.
Gastrooesophageal reflux disease (GORD) is a common disorder that has been linked to obesity (gradual increase in GORD symptoms as BMI increased).
Non-alcoholic fatty liver disease is increasing in prevalence in developed Countries, and is one of the most common causes of cryptogenic cirrhosis. It is strongly linked to the metabolic syndrome, of which obesity is a central component, and is in fact regarded as the hepatic manifestation of metabolic syndrome.
There is a marked increase in osteoarthritis in the obese. It is most common in the knees and the ankles, which may be a consequence of trauma related to excess body weight.
The WHO International Agency for Research on Cancer has estimated that overweight and inactivity account for from a quarter to a third of all cancers of the breast, colon, endometrium, kidney and oesophagus.
In a group of 294 patients seeking consultation for bariatric surgery, half the patients had a psychiatric disorder and. The highest prevalence rates were 29% for somatization, 18% for social phobia, for hypochondriasis and 14% for obsessivecompulsive disorder. In addition, eating disorders such as binge eating disorder and night eating syndrome have been linked with depression and obesity.
Gynaecological & obstetric complications
Obesity during pregnancy is associated with an increased risk of complications, including gestational diabetes, pre-eclampsia, and delivery complications such as macrosomia, shoulder dystocia and higher rates of caesarean sections and infections. Maternal obesity may also be an independent risk factor for neural tube defects and fetal mortality. Obesity is now estimated to be responsible for 6% of primary infertility. In men, there is a link between impotence and increasing infertility, with abdominal obesity a particular risk. Polycystic ovary syndrome (PCOS), the most common endocrine disorder in women of reproductive age, is characterized by a combination of chronic anovulation, polycystic ovary morphology and hyperandrogenism. Obesity and insulin resistance are closely related with PCOS, and insulin resistance has a pivotal role in the pathogenesis of this syndrome. Women with PCOS respond favourably to weight loss, as well as to pharmacological treatment of insulin resistance, with decrease in androgen levels and ovulation.
Chronic kidney disease
The epidemic of obesity in the developed world has been associated with an increase in the prevalence of chronic kidney disease.