This book provides up-to-date information on lesser-known eating disorders (EDs) and eating related disorders. EDs and eating-related disorders include a highly heterogeneous group of syndromes and symptoms characterized by abnormal eating and weight control behaviors that can appear in all genders and ages. EDs can lead to high rates of morbidity and mortality, especially if they are misdiagnosed and untreated. The risk of underestimation is high for the lesser-known ED, and when unhealthy eating behaviors appear in unusual situations, such as some medical and psychiatric pathologies, adults and the elderly, sexual minorities etc. The volume examines EDs in specific populations (the elderly, males, infants and toddlers, sexual minorities, etc.). Several chapters explore in detail lesser-known EDs (anorexia athletica, avoidant/restrictive food intake disorder, chewing and spitting, EDs by proxy, EDs after bariatric surgery, muscle dysmorphia, night-eating syndrome, nocturnal sleep-related eating disorder, orthorexia nervosa, pica, rumination disorder, etc.). Finally, other chapters address features of unhealthy eating and weight control behaviors associated with medical diseases (achalasia, craniopharyngioma, cystic fibrosis, cyclic vomiting syndrome, diabetes, dysphagia, Kleine-Levin syndrome, Klinefelter syndrome, Parkinson disease, Prader-Willi syndrome, Turner syndrome, etc.). The book will be a valuable resource for all health professionals who work in the fields of psychiatry, clinical psychology, eating disorders, obesity, medicine, clinical nutrition, public health, and prevention, allowing them to broaden their understanding of these disorders, and to enhance their clinical ability to diagnose them.