INS and obesity due to melanocortin 4 receptor deficiency: Methods: This narrative review is based on the literature published between 2015 and 2025 concerning the co-occurrence of GAD and obesity, with a focus on potential shared mechanisms including HPA axis dysregulation, chronic inflammation, oxidative stress, insulin resistance, gut–brain axis and microbiota dysbiosis, sleep disturbance, and maladaptive eating behaviors.