METABOLIC CONSEQUENCES OF OBESITY

One of the metabolic consequences of obesity is hyperlipidaemia. Obesity is characterized by increased adipose tissue cells. These cells over produce factors such as leptin and tumor necrosis factor (TNF- ALPHA)which cause cellular resistance to insulin. Initially, the pancreas maintains glycaemic control by over producing insulin leading to hyperinsulinaemia. Hyperinsulinaemia stimulates the sympathetic nervous system, which results in Na+ and water retention and vasoconstriction with increase blood pressure (hypertension). Insulin resistance also result in increased activity of hormone sensitive lipase which along with increased adiposity result in increased circulating free fatty acids. These excess free fatty acids are carried to the liver and converted to triacylglycerol and cholesterol. Excess triacylglycerol and cholesterol are released as very low density lipoprotein leading to higher circulating levels of both tricylglycerol and cholesterol. This also results in a decrease in high density lipoprotein which promotes atherosclerosis, CVC/CHD.

Eventually, the capacity of the pancreas to overproduce insulin declines, which leads to higher fasting blood glucose levels and decreased glucose tolerance. About 80% of adult onset (type 2) diabetics are overweight. Obesity and its associated metabolic changes which constitute its risk factors including hypertension, CVD and type 2 DM are also referred to as metabolic syndrome. This is nutritionally significant because of all these metabolic changes are reversible. Quite often reduction to ideal body weight is the single most important aim of nutritional therapy.