Treatment of Symptomatic Atrial Fibrillation

Eligibility Details: Inclusion Criteria: - paroxysmal or persistent AFIB (in sinus rhythm at the time of randomization) - BMI > 30 kg/m^2 or a waist circumference greater than 100 cm (male) or 90 cm (female) - have daily access to an iPhone - have at least one of the following risk factors:hypertension, diabetes or pre-diabetes, hyperlipidemia, smoker, obstructive sleep apnea Exclusion Criteria: - Permanent AFIB (AFIB lasting > 1 year) - Prior or actively on waiting list for catheter ablation for AFIB - History of unstable angina not corrected with revascularization - Left ventricular ejection fraction <30% - Left atrial size >5.5 cm - New York Heart Association (NYHA) classification IV heart failure - Moderate or severe cardiac valvular lesion (stenosis or regurgitation) on echocardiography or valvular lesion requiring intervention. - Participation in a cardiac rehabilitation program within the last year - Serious underlying psychiatric disorder: e.g. eating disorder, severe psychotic disorder with recent (3 month) hospitalization or psychiatric illness requiring supervised care precluding full independent function. - Participants who are unable or unwilling to provide fully informed consent. - Currently performing exercise training 150 minutes/week of moderate to vigorous physical activity - Gastrointestinal malabsorption disorder: A previously diagnosed gastrointestinal malabsorption disorder interfering with macro or micronutrient absorption. - If receiving warfarin and unstable international normalized ratio (INR) defined as persistently outside of the therapeutic range (2.0-3.0) for greater than 14 consecutive days. - Other non-cardiovascular medical conditions making 1-year survival unlikely.