Obesity is one of the biggest risks to public health in both developed and developing countries, and yet incidence continues to skyrocket. Being the main risk factor for a large number of life-limiting conditions, obesity has the potential to cause enormous damage unless addressed urgently. Heart failure (HF) is the most common cardiovascular disease associated with obesity. The incidence of HF overall continues to rise and mortality rates remain high, despite the rapid and significant advances in pharmacotherapy that have recently transformed the landscape of HF treatment. Both obesity and heart failure are multisystem disorders that are closely interlinked. Obesity poses the body a number of challenges, ranging from haemodynamic, to neuroendocrine, to inflammatory, to intracellular physiology. This narrative review describes the pathophysiological 'vicious cycle' caused by the combination of obesity and HF. Management of obesity in established heart failure has for years been a controversial topic, and yet an increasing body of evidence suggests that there are numerous benefits to managing obesity and insulin resistance in heart failure. Here, we review the existing evidence base, as well as exciting new developments, suggesting that we may finally be on the brink of a revolution in managing obesity in heart failure.