Effects of overfeeding in children with muscle dystrophies

In muscle dystrophies as in other muscle-wasting diseases and states, a progressive loss of muscle protein occurs, probably as a result of an imbalance between muscle protein synthesis and degradation. In the present study we examined whether this progressive muscle wasting and reduced functional capacity so damaging to patients with muscular dystrophies, can be reduced or even reversed by nightly overfeeding with 1000 ml of Osmolite in addition to the voluntary daytime dietary intake. In the Duchenne muscle dystrophy (DMD) group (six patients) body weight increased significantly accompanied by a 14% increase in midarm muscle circumference with only minimal changes in triceps skin fold, indicating a relative build up of muscle mass. In the congenital muscular dystrophy (CMD) group (four patients) no changes occurred in body weight or any of the three anthropometric measurements performed. Baseline nitrogen balance was mildly positive in both groups and improved significantly in the DMD group during the 3-month experimental period of refeeding, with no changes in urinary 3-methylhistidine excretion, suggesting improved muscle protein synthesis with no change in muscle protein degradation. No changes were detected in hematological and biochemical parameters, liver function tests, pulmonary function tests, or a general activity index during the study period. Our results suggest that a reduced rate of protein synthesis rather than an increased rate of protein degradation occur in muscle dystrophies, and that overfeeding might offer promising nutritional effects, at least in DMD patients.