hi this is Dr. Subhadeep.thanks for providing opportunity to help you.from your description it looks to me like an abdominal aorta pulsation which is prominent in thin individuals.it will be an immense help if you can tell me your weight and height. though you have told me that you are healthy but you have also mentioned of your anorexia and bulimia status.if anorexic habit is more dominant you might be having low body weight and hence your abdominal aorta pulsation scan be more prominent. however kindly get an ct angiogram done to rule out a rare chance of abdominal aortic aneurysm.if it happens to occur in your case then depending on the size the treatment will proceed. 1) if it is less than 5cm and growth rate less than 0.5cm/year and physically active young person like you nothing other than observation is required.if blood pressure is there control blood pressure with anti hypertensive drugs.stop smoking if u r a smoker.check ur cholesterol and if it is take antihyperlipidemic drugs.taking a drug should be under advise of authorized physician. if more than 5.5 cm painful tender aneurysm consult a vascular surgeon and according to his advise endo-aneurysmorrhaphy with intraluminal graft placement or endovascular aneurysm repair EVAR to be done as per vascular surgeon advise. needless to say though that chances of these conditions are very rare in your case regards Dr.Subhadeep Tripathy