The escalating prevalence of obesity has been linked to substantial increases in both metabolic and cardiovascular disease. Nevertheless, the direct effects of obesity on cardiovascular health and function require further exploration. In particular, the relationship between obesity and cardiac function has received intense scrutiny. Although obesity increases the risk for development of heart failure (HF), it appears to exert a protective effect in patients in whom HF has already been diagnosed (the “obesity paradox”). The protective effects of obesity in patients with previously diagnosed HF are the focus of particularly intense research. Several explanations have been proposed, but most studies are limited by the use of body mass index to classify obesity. Because body mass index does not distinguish between fat mass, fat-free mass, and lean mass, individuals with similar body mass indices may have vastly different body composition. This article discusses the roles of body composition, diet, cardiorespiratory fitness, and weight loss in the development of cardiac dysfunction and HF and the potential protective role that body composition compartments might play in improving HF prognosis. Based on an intensive literature search (Pubmed, Google Scholar) and critical review of the literature, we also discuss how a multidisciplinary approach including a nutritional intervention targeted to reduce systemic inflammation and lean mass–targeted exercise training could potentially exert beneficial effects for patients with HF.