From the Look AHEAD trial:
A total of 5,067 overweight or obese individuals 45 to 76 years old with type 2 diabetes without prevalent AF were randomized to either an intensive lifestyle intervention (ILI) designed to achieve and maintain weight loss through caloric reduction and increased physical activity or a diabetes support and education usual care group. Atrial fibrillation was ascertained from electrocardiograms at study examinations and hospitalization discharge summaries. Multivariable Cox models were used to estimate the intention-to-treat effect of the intervention adjusting for baseline covariates. During a mean follow-up of 9.0 years, 294 incident AF cases were identified. Rates of AF were comparable in the ILI and diabetes support and education groups (6.1 and 6.7 cases per 1,000 person-years, respectively, P = .42). The intervention did not affect AF incidence (multivariable hazard ratio [HR] 0.99, 95% CI 0.77-1.28). Similarly, neither weight loss nor improvement in physical fitness during the first year of the intervention was significantly associated with AF incidence: multivariable hazard ratio (95% CI) comparing top versus bottom quartile was 0.70 (0.41-1.18) for weight loss and 0.88 (0.55-1.43) for physical fitness improvement.Conclusion
In a large randomized trial of overweight and obese individuals with type 2 diabetes, an ILI that induced modest weight loss did not reduce the risk of developing AF.
This is a little disappointing. There is evidence that obesity is a risk factor for atrial fibrillation and it is appealing to believe that lifestyle modification is an effective treatment. In light of this study the best we can say at this point is that the evidence is mixed.