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Hyperphagia and obesity

The significant burden on people living with BBS

Hyperphagia and obesity can be among the most distressing symptoms of BBS1,2

While Bardet-Biedl syndrome (BBS) is syndromic with multiple and variable signs and symptoms, hyperphagia and early-onset obesity caused by impairment in the MC4R pathway are key differentiators from other causes of obesity.3
STILL SO HUNGRY brain image

Occurrence: Impairment is present at birth and leads to hyperphagia (insatiable hunger) and early-onset obesity3,4

  • May develop as young as 2 years old, often appearing in early childhood and continuing into adolescence and adulthood3,5

Cause: Rare genetic variants in the MC4R pathway, a signaling pathway in the hypothalamus3

Hunger due to MC4R pathway impairment is different from typical hunger

Episodic/Periodic

Occasional overeating

Eating beyond a feeling of satiety at a special occasion or celebratory meal (e.g., Thanksgiving).6

Hedonic overeating

Eating beyond satiety and metabolic needs. Influenced by appetite and cravings or having a preoccupation with food (e.g., "food noise").6-8

Cause:

  • The pleasure centers in the brain, often driven by emotion or environmental circumstances7
Binge eating

Episodic consumption of large amounts of food beyond hunger and/or satiety within a short period with a loss of control. If recurring, defined as Binge Eating Disorder.6,7

Behaviors:

  • Rapid eating9
  • Eating in isolation9
  • Distress due to eating behavior6,9

Cause:

  • Psychological factors, family history, dieting, gender4,9

Persistent

Hyperphagia caused by MC4R pathway impairment

A chronic pathological condition characterized by insatiable hunger, impaired satiety, and persistent abnormal food-seeking behaviors. Differentiated from other types of overeating by its severity and persistence. For some patients, symptoms and behaviors may range in severity.4,8

Characteristics4:

  • Persistent preoccupation with food
  • Prolonged time to satiation and shortened duration of satiety
  • Prolonged feeling of hunger
  • Specific abnormal behaviors

Behaviors:

  • Distress if food is unavailable
    • Children: may exhibit as tantrums or persistent negotiation/demand for food2,10
    • Adults: may manifest in emotional effects including sadness, frustration, irritability, anxiety and/or guilt2
  • Abnormal food-seeking behaviors such as night eating or hiding food (children may also steal/sneak food)11
  • Eating excessively—not to be confused with binge eating6

Cause:

  • Rare genetic variants in the melanocortin-4 receptor (MC4R) pathway, a signaling pathway in the hypothalamus3

Genetic testing through the Uncovering Rare Obesity® program is available for eligible patients.

UncoveringRareObesity.com

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The severity and presentation of the symptoms and behaviors associated with hyperphagia may vary by patient.8

Burden of hyperphagia

For some patients, hyperphagia may be among the most upsetting symptoms of BBS and has a significant impact on the daily lives of patients and their caregivers.1,2

Man lying in a bed. Actor portrayal.

“The most challenging symptom (of BBS) was hyperphagia. We did not anticipate the severity of the hunger. It is much more intense and ever-present, and impacted everything we did.”

– Caregiver of an individual living with BBS

Actor portrayal

Impact of hyperphagia on daily life2

Caregivers of patients with BBS reported moderate or significant impacts of hyperphagia on daily life:
51%

Familial relationships

54%

Sleep

56%

Mood/emotion

57%

Concentrating in school

62%

Leisure

Downloadable

Identify hyperphagia in your patients with early-onset obesity and intense hunger.

Hyperphagia questionnaire thumbnail

Hyperphagia Questionnaire

Burden of obesity

BBS is a progressive condition with long-term health complications. Patients with BBS and their caregivers report substantial burden related to obesity, including a negative impact on their emotional well-being, mental health, social life, and family relations, which may be a result of the early-onset and progressive nature of obesity due to BBS.1,2

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Obesity due to BBS has been reported in children as young as 2 years old.12
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The prevalence of obesity increases year over year in people with BBS. Nearly 93% are categorized as having overweight or obesity by early childhood.13

Because of early-onset obesity and continual hyperphagia, many patients develop other comorbidities, which in turn can have a further negative effect on overall clinical and mental health.1,4,13

Long-term effects of obesity-related sequelae in patients with BBS1,4,13

  • Diabetes
  • Cardiovascular disease
  • Kidney failure
  • Hypertension
  • Metabolic dysfunction-associated fatty liver disease
  • Overall negative impact on clinical and mental health

Renal anomalies due to BBS can be impacted by early-onset obesity, further compounding renal impairment.

Find out about a treatment option for obesity due to BBS.
Learn More

Questions about BBS?

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Recognizing BBS
References
  1. Forsythe E, Kenny J, Bacchelli C, et al. Managing Bardet-Biedl syndrome–now and in the future. Front Pediatr. 2018;6:23. doi:10.3389/fped.2018.00023
  2. Forsythe E, Mallya UG, Yang M, et al. Burden of hyperphagia and obesity in Bardet–Biedl syndrome: a multicountry survey. Orphanet J Rare Dis. 2023 Jan 16;18(1):12. doi:10.1186/s13023-023-02723-4
  3. Eneli I, Xu J, Webster M, et al. Tracing the effect of the melanocortin-4 receptor pathway in obesity: study design and methodology of the TEMPO registry. Appl Clin Genet. 2019 Jun 5;12:87-93. doi:10.2147/TACG.S199092
  4. Hampl SE, Hassink SG, Skinner AC, et al. Clinical practice guideline for the evaluation and treatment of children and adolescents with obesity. Pediatrics. 2023;151(2):e2022060640. doi:10.1542/peds.2022-060640
  5. Huvenne H, Dubern B, Clément K, et al. Rare genetic forms of obesity: clinical approach and current treatments in 2016. Obes Facts. 2016;9(3):158-173. doi:10.1159/000445061
  6. Haqq AM, Kebbe M, Tan Q, Manco M, Salas XR. Complexity and stigma of pediatric obesity. Child Obes. 2021 May 20;17(4):229-240. doi:10.1089/chi.2021.0003
  7. Espel-Huynh HM, Muratore AF, Lowe MR. A narrative review of the construct of hedonic hunger and its measurement by the Power of Food Scale. Obes Sci Pract. 2018 Feb 28;4(3):238-249. doi:10.1002/osp4.161
  8. Heymsfield SB, Clément K, Dubern B, et al. Defining hyperphagia for improved diagnosis and management of MC4R pathway-associated disease: a roundtable summary. Curr Obes Rep. 2025;14(1):13. Published 2025 Jan 25. doi:10.1007/s13679-024-00601-z
  9. NIH Symptoms and Causes of Binge Eating Disorder–NIDDK https://www.niddk.nih.gov/health-information/weight-management/binge-eating-disorder/symptoms-causes
  10. Heymsfield SB, Avena NM, Baier L, et al. Hyperphagia: current concepts and future directions proceedings of the 2nd International Conference on Hyperphagia. Obesity (Silver Spring). 2014 Feb;22(0 1):S1-S17. doi:10.1002/oby.20646
  11. Sherafat-Kazemzadeh R, Ivey L, Kahn SR, et al. Hyperphagia among patients with Bardet-Biedl syndrome. Pediatr Obes. 2013 Oct;8(5):e64-7. doi:10.1111/j.2047-6310.2013.00182
  12. Shoemaker A. Bardet-Biedl syndrome: a clinical overview focusing on diagnosis, outcomes and best-practice management. Diabetes Obes Metab. 2024;26(2):25-33. doi:10.1111/dom.15494
  13. Pomeroy J, Krentz AD, Richardson JG, Berg RL, VanWormer JJ, Haws RM. Bardet-Biedl syndrome: weight patterns and genetics in a rare obesity syndrome. Pediatr Obes. 2021 Feb;16(2):e12703. doi:10.1111/ijpo.12703

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