BackgroundSigns and symptoms of Bardet–Biedl syndrome (BBS) occur during early childhood, progress over time, and place substantial, multifaceted burden on patients and their caregivers. Hyperphagia may be a contributing factor to early-onset obesity in BBS; however, there are limited insights into its impacts on patients and caregivers. We quantified disease burden as it relates to the physical and emotional impacts of hyperphagia in BBS.MethodsThe CAREgiver Burden in BBS (CARE-BBS) study was a multicountry, cross-sectional survey of adult caregivers of patients with BBS who have had hyperphagia and obesity. The survey consisted of questionnaires including Symptoms of Hyperphagia, Impacts of Hyperphagia, Impact of Weight on Quality of Life (IWQOL)-Kids Parent Proxy, and Patient-Reported Outcome Measurement Information System (PROMIS) v1.0-Global Health 7. In addition, clinical characteristics, medical history, and weight management questions were included. Outcomes were scored and summarized descriptively in aggregate and by country, age, and obesity severity according to weight class.ResultsThere were 242 caregivers of patients with BBS who completed the survey. Caregivers observed hyperphagic behaviors throughout the day, with negotiating for food (90%) and waking up and asking or looking for food during the night (88%) being the most frequent. Hyperphagia had at least a moderate negative impact on most patients’ mood/emotions (56%), sleep (54%), school (57%), leisure (62%), and familial relationships (51%). Hyperphagia affected concentration at school (78%), and symptoms of BBS contributed to patients missing ≥ 1 day of school a week (82%). Responses from the IWQOL-Kids Parent Proxy suggested obesity most greatly negatively affected physical comfort (mean [standard deviation (SD)], 41.7 [17.2]), body esteem (41.0 [17.8]), and social life (41.7 [18.0]). On the PROMIS questionnaire, mean (SD) global health score for pediatric patients with BBS and overweight or obesity (36.8 [10.6]) was lower than the general population (mean, 50).ConclusionsEvidence from this study suggests that hyperphagia and obesity may have broad negative impacts on the lives of patients with BBS, including physical health, emotional well-being, school performance, and personal relationships. Therapies that target hyperphagia may alleviate the extensive clinical and nonclinical impacts experienced by patients with BBS and their caregivers.Supplementary InformationThe online version contains supplementary material available at 10.1186/s13023-023-02723-4.