Diet Composition in Prader-Willi Syndrome

Principal Investigator: Krista  Viau
Keywords: Prader-Willi Syndrome , Diet , Body composition Department: Pediatric Genetics
IRB Number: 00088861 Co Investigator: Dave Viskochil
Specialty: Pediatric Genetics
Sub Specialties: Medical Genetics
Recruitment Status: Not yet recruiting

Contact Information

Krista  Viau

Brief Summary

Obesity is a primary cause of morbidity and mortality in individuals with Prader-Willi Syndrome (PWS). PWS is a complex disorder characterized by hyperphagia, hypotonia, developmental delays with complex behavioral patterns, idiopathic scoliosis, and sleep abnormalities including obstructive sleep apnea. Development of morbid obesity can be ameliorated with severe and persistent energy restriction, only 50-75% of the energy requirements for age- and sex-matched children. Lean body mass is also reduced in PWS compared to BMI-matched controls resulting in reduced resting energy expenditure (REE) and physical activity due to increased fatigability. These factors combined with hyperphagia and behavioral issues drastically increase the risk of a child developing significant obesity with associated complications. Currently, the optimal composition of an energy-restricted diet to maximize lean body mass, maintain nutritional adequacy, and reduce the risk of dyslipidemia, hypertension, and impaired glucose tolerance in children with PWS is unknown. Our broad hypothesis is that implementation of improved diet quality, beyond caloric restriction, will improve anthropometric and nutritional outcomes in Prader-Willi syndrome.

We propose a randomized controlled trial for children with PWS aged 2 to 17 years comparing two treatment groups following an energy-restricted diet with different nutrient distributions. The Utah PWS Clinic currently treats 41 eligible patients and preliminary research suggests PWS patients in Utah are able to adhere to dietary recommendations. The current standard of care, known as the Red, Yellow, Green (RYG) diet, is centered on limiting high calorie, high fat foods. This results in a high carbohydrate, low fat diet (15% fat, 65% carbohydrate, 20% protein). In contrast, a high protein, moderate carbohydrate diet (30% fat, 45% carbohydrate, 25% protein) with adequate fiber (≥20 g/day) has been proposed as a means to reduce the percentage of fat mass and improve REE compared to those only restricting calories. Preserving lean body mass while reducing fat mass has the potential to increase REE and physical activity, thus reducing the risk of obesity. The proposed study will evaluate the effectiveness of a high protein, moderate carbohydrate diet compared to current dietary recommendations to maximize lean body mass, improve REE, and protect against dyslipidemia, hypertension, and impaired glucose tolerance. 

Specific Aim 1: Conduct a randomized controlled trial comparing a high protein, moderate carbohydrate diet to the RYG diet in patients with PWS aged 2 to 17 years. Patients will complete a 6-week run-in following the RYG diet before being randomized to a diet group. At baseline and week 16, all participants will be evaluated for body composition, REE, anthropometrics (BMI, waist circumference), a fasting lipid panel and hemoglobin A1c and vitals. Intra-subject change will be compared between dietary groups.

Hypothesis 1a: Body composition (i.e., percentage lean body mass) will increase after 16 weeks in PWS patients on a high protein, moderate carbohydrate diet compared to PWS patients on the RYG diet.

Hypothesis 1b: A high protein, moderate carbohydrate diet improves overall metabolic status after 16 weeks in patients with PWS.

Specific Aim 2: Participants randomized to the high protein, moderate carbohydrate diet and the RYG diet will be evaluated monthly for adherence to the study diets using three-day diet records and 24-hour recalls. Adherence to dietary therapy is defined as being within 10% of goal carbohydrate intake (percentage of total calories) and calorie intake.

Hypothesis 2: There will be no difference in mean participant adherence to the study diet between the RYG diet and the high protein, moderate carbohydrate study groups.

Inclusion Criteria

Diagnosed with Prader-Willi Syndrome

Aged 2-17 years

English speaking

Access to the Internet


Exclusion Criteria

Individuals starting or stopping growth hormone therapy during the trial

Starting growth hormone therapy within 6 months of enrollment

Enrolled in concurrent clinical trials investigating pharmacological treatments for PWS