Impact of Bariatric Surgery on Obesity Related Metabolic Diseases

Abstract

Obesity is a major public health challenge; it is widespread, highly prevalent and has clinical implications with potential negative effects on almost every organ system, as well as being a psychosocial and economic burden. Obesity is usually defined using the body mass index (BMI). Worldwide prevalence of Metabolic Syndrome ranges from <10% to as much as 84%, depending on the region, urban or rural environment, composition (sex, age, race, and ethnicity) of the population studied.It is expected that one-quarter of the world's adult population has Metabolic Syndrome. Current approaches to therapeutic weight loss include lifestyle modification, pharmacotherapy, and bariatric surgery. Current surgical practice can be divided by the mechanism of weight reduction: restrictive by decreasing the storage capacity of the stomach, malabsorptive through surgical bypass thus excluding intestinal loops, or a combination of restriction and malapsorption. Bariatric surgery leads to an early improvement of lipid metabolism not only fasting but also postprandially. Improvements in glucose and lipid metabolism after weight loss interventions are often associated with increased glucose uptake and clearance by muscle, adipose and liver tissues, decreased lipogenesis in peripheral tissues, and/or enhanced lipid oxidation in muscle. RYGB surgery reverses dyslipidaemia associated with obesity. Although improvements in TG and HDL-C levels are seen only after weight loss has occurred, the changes in total cholesterol and LDL-C which persist long term, start to occur immediately after RYGB, suggesting different weight independent mechanisms. Decreased sterol absorption leads to decreased cholesterol and LDL cholesterol levels, accompanied by enhanced cholesterol synthesis and enhanced cholesterol catabolism. Reductions in branched chain amino acids ceramides and nervonic acid have been shown to correlate with improvement in glucose homeostasis.