Resting metabolic rate and body composition of achondroplastic dwarfs

Indirect calorimetry was used to measure resting metabolic rates (RMR), and densitometry and anthropometry were used to measure body fat and fat-free masses of 32 adults with very short stature. Twenty-seven of them were achondroplastic dwarfs. Their results were compared to those obtained from 103 lean and obese adults with normal heights. All 32 dwarfs had distinctly greater RMR per kg fat-free mass by densitometry than adults with average stature. However, there was a wide variation in the RMR among dwarfs, which was independent of leanness or obesity. In spite of increased RMR, obesity among dysplastic adult dwarfs was twice as prevalent as among average-height adults. Increased abdominal:hip ratios were prevalent among dwarfs, but these ratios do not reflect body fat. Body mass indices were worthless, and skinfold thicknesses and other anthropometric measurements were of very limited value in predicting the body fat of dwarfs. Although our new and specific equations for estimating RMR and body composition give reasonable values, we recommend that the caloric requirements and body compositional variables be measured if nutritional therapy is needed to induce weight loss or gain in Little People.