Some people experience palps after eating heavy meals that are rich in carb, sugar, fat, high level of MSG, nitrates & sodium (webmd. Com). Why could?

Multiple responses. Carbs and sugar effect changes in insulin and blood sugar levels which, when abnormal, can cause palpitations. SMG and sodium causes salt and fluid retention, high blood pressure and heart failure with palpitations. Nitrates cause asthma and allergies in some. I'm not aware of fat causing immediate palpitations.