Obesity is repeatedly proclaimed an important risk factor for atrial fibrillation (AF) and considered one of the most promising targets for prevention. This widely held view has been questioned by recent findings, which suggest that AF risk is associated with a high lean (aka fat-free) body mass, whereas fat carries little or no independent risk of AF. Focusing on these recent results, the present overview summarizes and interprets the evidence underlying this apparent controversy and discusses whether a change of paradigm is warranted in AF research or in clinical practice. The overall conclusion is that the excess AF risk in obese persons seems primarily associated with other characteristics than the amount of adipose tissue per se.