Changes in the basal metabolic rate of the malnourished infant and their relation to body composition

ABSTRACT

1. The basal metabolic rate (BMR) was studied by a closed-circuit system in 36 infants suffering from and recovering from severe protein malnutrition. In nine cases, concomitant studies were made of total body water by tritium diultion. 2. In most cases, the initial oxygen consumption tended to be subnormal in relation to calculated surface area, but was approximately normal in terms of body weight and body of solid mass. However, owing to an abnormal preponderance of the most metabolically active organs, notably the brain, this finding suggests a true depression of respiratory activity in the individual organs. In a few marasmic cases, the BMR was initially increased both in terms of body weight and surface area. 3. Serial tests showed a dramatic rise in total oxygen consumption, often more than twofold, during the early weeks of recovery. This rise was followed by a plateau level which was maintained regardless of variable gains in weight. Total oxygen consumption at this plateau level approached the normal for a healthy child of the same age. 4. Body weight did not increase unless the caloric intake consistently exceeded the BMR by 60 to 85 calories per kg per day. The greater the weight deficit, the higher was the BMR during recovery and the higher the caloric requirement for weight gain. 5. It is suggested that the limit of oxygen uptake in recovery may be determined partly through restoration of normal activity in the organs which are least reduced in relation to age and partly through the factor of the mean "metabolic potential" of the individual cell. Cell number per unit of tissue mass is increased in the active tissues of the malnourished growing animal. The mean respiratory activity per cell is therefore much reduced initially, but may approach the normal during recovery (SUMMARY)