Obesity is a serious health concern. The secondary effects of obesity are serious and include an increased risk of cardiovascular disease. In this regard, as body weight rises, systemic inflammation occurs and this increases the risk of cardiovascular disease. This is because inflammation is a cause of oxidative stress which is able to cause endothelial dysfunction due to inhibition of the synthesis of nitric oxide, the latter being required for the correct dilation of blood vessels in response to blood flow. Endothelial dysfunction leads to reduced vessel diameter in response to flow, and the increased resistance increases blood pressure. Further, obesity is associated with low quality diets, which can often be deficient in antioxidants such as vitamin C. This increases the oxidative stress further, but low intakes of vitamin C may also lead to scorbutic bleeding of blood vessels and the formation of atherosclerotic plaques. The loss of elasticity in blood vessels due to these changes characterises cardiovascular disease.
Concomitant to the changes to the endothelium of the blood vessels, poor quality diets cause changes in lipoprotein metabolism, and this is reflected in changes to the amount and types of cholesterol transported in blood. This likely occurs through a process of energy overload in the liver that increased flux through the do novo lipogenesis pathways to create large amounts of fatty acids. These fatty acids accumulate in tissues including the liver and cause insulin resistance. This insulin resistance disturbs energy metabolism and this leads to changes in cholesterol transport. The modified lipoprotein and blood cholesterol levels are therefore not a cause of cardiovascular disease, but occur simultaneously as a confounding variable. As weight gain and poor diet are the likely cause of cardiovascular disease and the lipoprotein changes, it seems logical that reversing the weight gain would also reverse the lipoprotein changes. And this is exactly what is evidenced in the nutritional literature.
For example, in one study1, researchers assessed the effects of weight loss on the cholesterol blood levels of Jejunoileal bypass patients. Subjects were undergoing a 4 inch end-to-side bypass to treat morbid obesity and their cholesterol levels were monitored before and after surgery by the researchers. The results showed that the operation cause a reduction in the mean weight of the subjects over a 7 month period from 127 kg to 98 kg. Concomitant to this weight loss was a reduction in total cholesterol from 185 mg/dL to 116 mg/dL. The high density lipoprotein (HDL) cholesterol component also decreased from 40 mg/dL to 34 mg/dL. However, the total to HDL cholesterol ratio decreased, suggesting that the subjects were at a significantly lower risk of cardiovascular disease. Although the weight loss in this study was caused by surgical intervention, other studies support the contention that the easiest way to improve cholesterol levels and improve health is to lose weight through eating a high quality diet.
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