The motivation to seek palatable, energy-dense food evolved as a key mechanism for survival and maturation in an environment with limited food availability. Given that heightened motivation for palatable food in an environment of low food availability shaped an evolutionary benefit, it is not surprising that neural circuits controlling and responding to body weight have a profound effect on motivation and adaptive behaviour. We are particularly interested in how the brain senses low food availability to appropriately control motivated and adaptive appetitive behaviours, such as increase exploration and reduced anxiety. An understanding of these processes may offer insight into the pathogenesis of obesity or altered behavioural control as seen in eating disorders. The peripheral hormone ghrelin and its key neural target population, Agouti-related peptide (AgRP) neurons, are critical components of the body’s response to hunger and low food availability. Ghrelin is often referred to as a hunger-signalling hormone and AgRP neurons are often referred as hunger-sensing neurons. In this talk I will discuss how AgRP neurons and ghrelin receptor-expressing neurons respond to hunger and influence behavioural responses to ensure adequate food consumption. This includes the impact on motivated behaviour through dopamine signalling and adaptive behaviours involved in mood control.