Genetic forms of obesity, including monogenic (MO) and syndromic (SO) obesity, are characterised by severe, early-onset weight gain due to disrupted central regulation of body weight, typically involv Show more
Genetic forms of obesity, including monogenic (MO) and syndromic (SO) obesity, are characterised by severe, early-onset weight gain due to disrupted central regulation of body weight, typically involving key pathways such as the leptin-melanocortin axis. These alterations result in marked hyperphagia and complex eating behaviours, yet clinical characterisation remains limited. This review aimed to describe the multidimensional eating behaviour profiles across genetically confirmed obesity, explore their variability, and evaluate existing assessment tools to support early diagnosis, personalised care, and therapeutic monitoring. We conducted a systematic review following PRISMA guidelines including publications up to 4 September 2025. A total of 162 studies involving individuals with genetically confirmed SO or MO were analysed. Eating behaviours were categorised into nine dimensions: food-centred thinking, food-seeking/stealing, hunger/satiety, ingestive/oral behaviours, nutritional quality, food preferences, food acceptability, loss of control eating, and eating restraint. Assessment tools and methodologies were systematically reviewed. Hyperphagia was consistently reported across genetic aetiologies, though definitions and measures remain heterogeneous. Prader-Willi syndrome (PWS), the most studied condition, was associated with early-onset hyperphagia, increased hunger, pronounced food preoccupation, compulsive food-seeking/stealing and strong preferences for carbohydrate-rich, large quantities and unusual food items. Similar behavioural traits were found in other SO and MO, including Bardet-Biedl syndrome, Alström syndrome, Fragile X syndrome, WAGR syndrome, pseudohypoparathyroidism Ia, 16p11.2 deletion and LEPR, POMC, and MC4R deficiencies. Behavioural traits appeared relatively consistent across sex, age, and genotypes within syndromes. Most studies relied on caregiver reports; existing tools such as the Hyperphagia Questionnaire (HQ) and Food-Related Problem Questionnaire (FRPQ), developed primarily for PWS, did not fully capture the behavioural spectrum or suit all cognitive profiles. Tools applicable to individuals without intellectual developmental disorders, particularly adults living independently, remain scarce. This is the first systematic review to comprehensively map eating behaviours across rare genetic obesity using a multidimensional approach. It highlights the shared feature of disrupted appetite regulation and emphasises the need for standardised, multidimensional tools suitable for both clinical and research contexts. Better behavioural characterisation will support targeted therapies and improve outcome monitoring in these high-need populations. Show less