Obesity in Australia

Obesity is becoming a major health problem in developing countries like Australia, North America, Europe and other developing nations. The Australian Diabetes, obesity and life style study (AUSDIAB) predicts the changes in glucose indices; health behaviour and incidence of diabetes in 5 year follow up experiments among 5842 participants (Barr et al., 2007). This study suggests that a large number of Australians suffered mortality due to cardiovascular diseases associated with abnormal glucose metabolism every year. The Framingham Heart Study revealed that hypertension, diabetes and left ventricular remodelling lead to the development of congestive heart failure (Levy et al., 1996). The Framingham Heart Study also found that a 5% increase in weight increases the chance of hypertension by 30% over a four-year period of time. An increased sympathetic activity, impaired renin-angiotensin system, retention of fluid volume, peripheral vasoconstriction, dyslipidaemia, increased blood viscosity due to the increased haematocrit and fibrinogen may increase pressure overload on heart in obesity (Schunkert, 2002). Several studies also suggest that the cause of hypertension itself may contribute to left ventricular hypertrophy in obese individuals as the increase of BMI increases the chance of hypertension (De Simone et al., 1994; Avelar et al., 2007). High dietary fat intake increases the expression of angiotensin IB(AT1B) and Endothelin A (ETA) receptors (Neilsen et al., 2004; Zhang et al., 2005). Plasma concentrations of angiotensin II and endothelin 1 (physiological vasoconstrictor agents) were increased in both obese patients and animal models (Barton et al., 2000; Neilsen et al., 2004; Zhang et al., 2005). Recent studies have shown that reduced synthesis of nitric oxide (NO; a major vasodilator) from L-arginine in endothelial cells is a major factor contributing to the impaired action of insulin in the vasculature of obese and diabetic subjects. Obesity results from an imbalance between energy intake and expenditure. Growing evidence suggests that arginine plays an important role in regulating metabolism of energy substrates in mammals (Frank et al. 2007; Jobgen et al. 2006). NO is synthesized from L-arginine by NO synthase. As a signalling molecule, physiological levels of NO stimulate glucose uptake, as well as glucose and fatty-acid oxidation in skeletal muscle, heart, liver, and adipose tissues (Jobgen et al. 2006). Nitric oxide also inhibits the synthesis of glucose, glycogen and lipid in liver and adipose tissues and enhances lipolysis in subcutaneous adipocytes (Jobgen et al.