Resting energy expenditure and energy substrate utilization in children with Duchenne muscular dystrophy

The high prevalence of obesity at an early stage of Duchenne muscular dystrophy (DMD) could result not solely from reduced physical activity, but may also involve low resting energy expenditure (REE), abnormal nutrient utilization, or overfeeding. We hypothesized that the dramatic muscle mass loss in DMD should reduce the REE. REE was measured by indirect calorimetry in 13 9-13-y-old DMD boys (5 obese, 8 nonobese) and 9 male age-matched controls. Muscle mass was estimated from 3-d creatinine excretion in urine. Daily energy intake was estimated from 7-d diet records. In the nonobese DMD group (NODMD) the muscle mass was reduced by 71%, and the REE was 13% lower than in controls (47.5 versus 54.6 kcal.h-1, p < 0.05). Postabsorptive respiratory quotients appeared higher in both DMD groups than in the controls; however, the difference was significant only for the NODMD group (0.88 versus 0.83, p < 0.05). Respiratory quotients were not different between the two DMD groups. Diet records were not contributive in revealing a different dietary behavior between groups. Our results suggest that: 1) muscle mass loss in DMD is associated with a low REE, 2) low postabsorptive fat utilization might occur at an early stage of the disease, and 3) obesity is not associated with an increase in fat utilization in DMD. This study warrants further research to test low REE and low fat utilization as risk factors in developing obesity in DMD.