Obesity is defined as an excess of adipose tissue that imparts health risk; a body weight of 20% excess over ideal weight for age, sex and height is considered a health risk.
The most widely used method to gauge obesity is body mass index (BMI) which is equal to weight in kg/height in m2.
ETIOLOGY
Obesity results when caloric intake exceeds utilisation.
The imbalance of these two components can occur in the following situations:
- Inadequate pushing of oneself away from the dining table causing overeating.
- Insufficient pushing of oneself out of the chair leading to inactivity and sedentary life style.
- Genetic predisposition to develop obesity.
- Diets largely derived from carbohydrates and fats than protein-rich diet.
- Secondary obesity may result following a number of underlying diseases such as hypothyroidism, Cushing’s disease, insulinoma and hypothalamic disorders.
PATHOGENESIS
- Lipid storing cells, adipocytes comprise the adipose tissue
- Present in vascular and stromal compartment in the body.
|
- These cells also release endocrine-regulating molecules.
- Include: energy regulatory hormone (leptin), tnf-α and interleukin-6, insulin sensitivity regulating agents ,prothrombotic factors, and angiotensinogen
|
- Adipose mass is increased due to enlargement of adipose cells due to excess of intracellular lipid deposition as well as due to increase in the number of adipocytes.
|
Recently, two obesity genes have been found: ob gene and its protein product leptin, and db gene and its protein product leptin receptor.
SEQUELAE OF OBESITY.
| Hyperinsulinaemia. |
- Increased insulin secretion
- individuals exhibit hyperglycaemia or frank diabetes despite hyperinsulinaemia.
|
| Type 2 diabetes mellitus |
- Strong association of type 2 diabetes mellitus with obesity.
- Exacerbates the diabetic state and in many cases weight reduction often leads to amelioration of diabetes.
|
| Hypertension |
- Observed which is perhaps due to increased blood volume. Weight reduction leads to significant reduction in systolic blood pressure.
|
| Hyperlipoproteinaemia. |
- Plasma cholesterol circulates in the blood as low-density lipoprotein (LDL) containing most of the circulating triglycerides.
- Associated with VLDL and mildly with LDL.
- Total blood cholesterol levels are also elevated in obesity.
|
| Atherosclerosis |
- There is increased risk of myocardial infarction and stroke in obese individuals.
|
| Nonalcoholic fatty liver disease (NAFLD). |
- NAFLD which may progress further to cirrhosis of the liver.
|
| Cholelithiasis |
- Six times higher incidence of gallstones in obese persons, mainly due to increased total body cholesterol.
|
| Hypoventilation syndrome (Pickwickian syndrome). |
- Characterised by hypersomnolence, both at night and during day in obese individuals along with carbon dioxide retention, hypoxia, polycythaemia and eventually right-sided heart failure
|
| Osteoarthritis |
- More prone to develop degenerative joint disease due to wear and tear following trauma to joints as a result of large body weight.
|
| Cancer |
- Associated with higher incidence of cancers of colon, breast, endometrium and prostate
|
