Endocrine Abstracts

Background: Children with Prader–Willi syndrome (PWS) have a predictable pattern of weight gain, with obesity beginning in early childhood and worsening as they get older. They have low tone and as a result their energy requirements are lower (typically 60% estimated average requirement for energy (EAR)) than age matched controls. We present three case studies of children with PWS who have been following a modified macronutrient diet, with significant positive changes to their body composition and/or BMI. The modified macronutrient diet aimed to increase the proportion of energy from protein (25%) and fat (30%) and lower the proportion from carbohydrate (45%) compared to guidance for the general population, as well as having a high fibre content (>20 g/day). Individuals worked with their dietician to create personalised stepwise plans to move their current intake towards these levels. Follow-up measurements were taken between 9 and 12 months after starting the dietary changes.

Results: The first case is an 11-year-old boy and his BMI decreased from 26.7 (>99.6th centile) to 23 (98th centile). His fat mass decreased from 24.5 kg (41.4%) to 19.6 kg (35.2%) and muscle mass increased from 32.9 to 34.2 kg. The second case is an 18-year-old female and her fat mass reduced from 30.7 kg (43.6%) to 27.6 kg (39.2%) and muscle mass increased from 37.6 to 40.7 kg. A third case, a 5-year-old boy, is following the same diet but is too young to accurately measure bio-impedance with current equipment. Positive effects on BMI have been seen though from 22.1 kg/m² (above +3.5 S.D.) to 19.1 kg/m² (above 98th centile) over a 1-year period.

Conclusion: The results from these three cases indicate that an energy restricted diet with a well-balanced macronutrient composition and fibre intake improves both BMI and body composition in children with PWS compared to a simple energy-restricted diet.