Thank you for the query. I would like to know your sister s age and whether she has any other associated conditions like hypertension, diabetes mellitus and thyroid dysfunction, apart from being overweight. Overweight or obesity, are definitely risk factors and may be part of Metabolic syndrome. I would recommend to get her lipid profile checked, since dyslipidemia is a risk factor for coronary artery disease (one of the manifestations being heart attack). The symptoms that you have provided, can very well be the symptoms pf an acute coronary syndrome. Palpitations may be due to an underlying cardiac arrythmia (which can arise due to a number of reasons). A 12 lead ECG (if not done) may help out. A hemoglobin and thyroid profile need to be checked, since derangement in both can cause, fatigue, dizziness and palpitation. Please do visit your cardiologist for a thorough physical check-up. Some other investigations (like an echocardiography may be needed). If lipid profiles are deranged she needs to be started on medications (like statins). If ischemic heart disease is detected, a plan of management is needed. It is imperative that she loses weight, by a daily exercise regimen (even simple walking may help). Hope this helps you out. Regards Dr. Ayusmati Thakur