Childhood protein-energy undernutrition (PEU) is a well-recognized problem and therefore a lot of work has been done to identify and manage paediatric PEU. Though there have been several reports of low protein consumption in adults from developing countries, PEU and its subtle forms (subclinical PEU) are not yet recognized as adult disorders. Physicians and public perception do not favour easy recognition and action. In this review, the authors provide a scoping review of the existing literature on this entity providing insights into its recognition, pathogenesis and management. Adult subclinical PEU is an enormous under-recognized challenge that can have detrimental consequences if not recognized and corrected in time. PEU has grave health and economic impact on the patient and society. Therefore, it is important to recognize subclinical PEU and prevent its progression to full-blown form.