OBESITY !

By: Miriam Ramez

What is obesity?Obesity is a medical condition involving an excessive increase in body fat (excessive energy intake compared to energy usage) to an extent that it may have a negative effect on health.

What is BMI?Body mass index is used to categorize if a person is underweight, normal, overweight or obese.It is calculated by dividing a persons weight over the square of his or her height.

Associated diseases: Heart disease Liver problems (fatty liver) Obstructive sleep apnea Certain types of cancer Osteoarthritis Asthma Metabolic syndrome (diabetes type 2,

high blood pressure, high triacylglycerol, low levels of HDL, and insulin resistance)

Causes of obesity: Unhealthy diet (excessive intake of fat and

carbohydrates) Inactivity Pregnancy Lack of sleep Certain medications Endocrine disorders (hypothyroidism or

cushing disease) Few due to genetics (leptin) or psychiatric

illness

Genetic contribution: leptin gene: leptin is secreted from the

adipocytes, circulates into the blood until it reaches the arcuate nucleus in the hypothalamus to cause a decrease in food intake, mutations in the actions of leptin can cause obesity.

Note: Leptin levels is high in obesity and leptin resistance is likely.

Beta 3 adrenergic receptor gene, adiponectin gene, peroxisome proliferator activated peptide receptor gamma gene (PPAR-gamma).

Obesity and insulin resistance: Adipose tissue is not only a storage for

triacyglycerides but also is an endocrine gland that releases chemical messengers called adipokines.

Insulin resistance is seen in Obesity and type 2 diabetes.

FREE FATTY ACIDS: Increased adipose tissue stores, a disturbed insulin-mediated regulation of lipolysis and subnormal skeletal muscle FFA uptake under conditions of high lipolytic rate may increase circulating FFA concentrations.

Which leads to insulin resistance( elevated levels of blood glucose and insulin) in liver and skeletal muscle and affects beta-cell function.

High FFA in the blood, Reduces glucose uptake and metabolism by the skeletal muscle, resulting in the fasting levels of blood glucose and an increase in insulin secretion, prolonged overproduction of insulin can cause failure of the Beta-cells, resulting in type 2 diabetes.

An imbalance between FFA uptake and FFA oxidation may in turn be a factor promoting accumulation of triacylglycerols within skeletal muscle, which is strongly associated with skeletal muscle insulin resistance.

ADIPOKINES:

TNF alpha(cytokines) is highly expressed in obesity, inhibits the synthesis of several other adipocyte-specific proteins and enhances the release of FFA from adipose tissue, this improves insulin sensitivity by increasing the activity of the insulin receptor tyrosine kinase.Leptin : Leptin decreases neuropeptide Y in the hypothalamus and should suppress appetiteAdiponectin: Adiponectin exhibits potent anti-inflammatory and anti-atherosclerotic effects, its production is reduced during insulin resistance.PAI-1 is the primary physiological inhibitor of plasminogen activation in blood and is known to contribute to thrombus formation and development of heart disease, which is increased during insulin resistance.

Treatment: Healthy diet Exercise Sleep enough Surgery (removing part of the stomach or by

reducing its size) Prevent fat absorption by orlistat (xenical) Use of compounds such as Beta-phenylalanine

which reduces food intake. Re-esterification of FFA into triacylglycerols by

thiazolidinedione drugs.