Obesity is a complex disorder involving an excessive amount of body fat,increasing the risk for various diseases.The causes,effects,pathophysiology and treatment of obesity was looked into.The treatment included dieting and physical exercise,weight-loss surgeries,and antiobesity drugs.Some antiobesity drugs been used was looked into,including its mechanism of action and side effects.The conclusion was that pharmacological and non-pharmacoloical methods are needed in long term treatment of obesity.