Orexigenic is a term used to describe substances, neurons, or pathways that stimulate appetite and increase food intake. The word is derived from the Greek 'orexis,' meaning appetite. In the brain, the primary orexigenic center is located within the hypothalamus, specifically involving neurons that release Neuropeptide Y (NPY) and Agouti-related peptide (AgRP).
Orexigenic signals are typically triggered by low energy levels, high stress, or the sight and smell of palatable food. Hormones like ghrelin are potent orexigenic agents that travel from the gut to the brain to initiate the drive to eat. In metabolic dysfunction, orexigenic pathways can become overactive or fail to be properly inhibited by satiety signals, leading to chronic overeating and difficulty maintaining weight loss. Balancing orexigenic and anorexigenic (appetite-suppressing) signals is the core objective of hypothalamic harmony.
The definitive guide by Russell Clark, FNP-C, APRN