Overweight and obesity are estimated at high prevalence and progression in adults; they are major contributors to chronic diseases and a major public health challenge. An obese habitus changes body-surface electrocardiograms (ECGs). Obesity is responsible for geometric changes to the heart and torso, as well as for deleterious electrophysiological changes of the heart. Common ECG changes, reduced voltages in the precordial leads, and axis deviation have made the search for left ventricular hypertrophy (LVH) even more problematic. Identification of LVH by ECG is difficult and time consuming but ECG is fundamental to reveal abnormalities of clinical relevance associated with obesity. The QTc dispersion assessment and the comparison with magnetic resonance imaging are the frontiers to clarify the connection between ECG LVH signs and overweight and obesity.