The following are points to remember from this review about the effects of weight loss and exercise on obesity and atrial fibrillation (AF):

1. Overweight and obesity likely increase AF risk by increasing cardiac output leading to left ventricular hypertrophy in association with diastolic dysfunction and left atrial (LA) remodeling. Neurohormonal and metabolic alterations associated with obesity include activation of the renin-angiotensin-aldosterone system and sympathetic nervous system, and hyperleptinemia, which contribute to LA enlargement. Pulmonary hypertension is also associated with obesity and right ventricular and right atrial enlargement.
2. Comorbidities including hypertension, obstructive sleep apnea, heart disease, and diabetes are all associated with obesity and an increased risk for AF.
3. Pericardial and epicardial adipose fat are both biologically active, and are associated with an increased risk for AF. Increased pericardial fat is predictive of recurrent AF after catheter ablation. These fat deposits may induce atrial fibrosis, through immune or inflammatory responses. It has also been hypothesized that inflammatory cytokines and chemokines may facilitate fibrosis of LA myocardium, predisposing to the development of micro-reentry circuits. Limited data exist to suggest that reducing these fat deposits is associated with lower risk for AF.
4. Obesity can modify medical management through pharmacokinetics of antiarrhythmics and anticoagulants, and can increase the risk of adverse outcomes for ablation and cardioversion.
5. Weight loss is associated with a reduced risk of AF in some but not all studies. The amount of weight lost may be a factor. Control of additional risk factors such as hypertension and sleep apnea also contribute to a lower risk. Physical activity has been associated with AF in some studies, while others have not demonstrated an association. Being physically active helps control risk factors for AF including increasing weight, hypertension, and diabetes; thus, it is recommended in current guidelines, together with other risk factor management strategies.

Keywords: Adiposity, Anti-Arrhythmia Agents, Anticoagulants, Arrhythmias, Cardiac, Atrial Fibrillation, Cardiac Output, Catheter Ablation, Diabetes Mellitus, Exercise, Hypertension, Hypertension, Pulmonary, Hypertrophy, Left Ventricular, Myocardium, Obesity, Overweight, Primary Prevention, Renin-Angiotensin System, Risk Factors, Sleep Apnea, Obstructive, Sleep Apnea Syndromes, Sympathetic Nervous System, Weight Loss

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