This report presents an account of energy balance of young Jamaican children recovering from protein-energy malnutrition (PEM). This was done in three steps. Initially the true gross energy of a formula used in the treatment of PEM was determined by bomb calorimetry. Then its metabolizable energy content was determined in a group of nine children recovering from PEM. In a similar but different group of eight children total daily metabolizable energy intake (EI), average rate of weight gain (g/kg/day) (WG), and total daily energy expenditure (TDEE) were determined. TDEE was determined by indirect calorimetry using a heart rate counter and is based on the relationship of heart rate to oxygen consumption. In this group, the mean EI was 122.5 kcal, WG was 8.4 g, and TDEE was 92 kcal. The difference between EI and TDEE was 30.7 kcal/kg, or 3.3 kcal/g of weight gain. This difference is presumed to be the stored energy in new tissue and corresponds to a proposed new tissue composition of 31% fat and 14% protein. A regression curve comparison of WG versus EI showed that at zero weight gain EI was 85.5 kcal and each additional gain. The difference of 1.0 kcal between total energy cost and stored energy reflects the energy required to deposit new tissue. Gram weight gain required 4.4 kcal. The latter figure is felt to reflect the total energy cost of weight. From three independent measurements, an estimate of maintenance energy requirements was estimated to be about 82 kcal/kg/day.

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1. Rates of total protein turnover, synthesis and breakdown were measured in five children before and after recovery from severe protein-energy malnutrition and while receiving 0.6 g of protein and 397 kJ day-1 kg-1. 2. Thes rates were calculated after giving doses of [15N]glycine every 2 h along with the feeds and measuring the rate of excretion of [15N]urea in urine. 3. Malnourished children had significantly lower rates of protein turnover, synthesis and breakdown than after they had recovered. 4. During recovery from protein-energy malnutrition, two children on a daily intake of 1.2 g of protein and 605 J/kg body weight, had rates of protein turnover, synthesis and breakdown that were twice as great as those found on admission and higher than after recovery. 5. On the study diet the malnourished children maintained their weight while the recovered children lost weight; the apparent nitrogen balance was more positive in the malnourished children. 6. In recovered children, the rate of protein synthesis was unchanged over a wide range of protein intake, whereas the rate of protein breakdown appeared to rise with a reduction in protein intake.

Extractcreatine in normal individuals (13,19,21) and is remarkablyIn eight infants and children who had recovered from proteinenergy malnutrition (PEM), muscle mass was estimated by measuring creatine turnover by an isotope dilution technique using [15N]creatine, creatine concentration, and urinary creatinine output. Creatine turnover varied from 1.5 to 2.6% of the muscle creatine pool per day and muscle creatine concentration ranged from 1.7 to 3.9 rglPg muscle D N A . Muscle mass was between 15% and 37% of total body weight. The results indicate that daily creatinine output is not a reliable indicator of muscle mass in children who have recently recovered from severe PEM. Speculation constant although there is sufficient variation between individuals to affect the creatinine excretion per unit of body creatine. The concentration in muscle also shows individual variation (I). When the daily excretion of urinary creatinine is used to estimate muscle mass, it is important to recognize that both creatine turnover (13,35) and creatine content of muscle (1) vary in the individual in differing clinical states. Other workers have pointed out the unreliability of using a single constant to relate muscle mass to creatinine excretion (21). In the present study we have measured creatine turnover and creatine concentration in muscle in estimating muscle mass in children. THEORETICAL CONSIDERATIONS AND CALCULATIONS Short term fluctuations in the daily creatinine output in young children may be due to variations in muscle creatine concentrationSince more than 90% of body creatine is found in muscle, from a knowledge of the size of the creatine pool and the concentration of since creatine turnover, in the individual subject, remains re-creatine in muscle, muscle mass can be estimated markably constant. The wide variation in the proportion of body weight that is muscle may reflect significant body composition Muscle mass (kg) . -. changes in fat, water, and muscle in children who have recoveredcreatine pool (g) from severe protein-energy malnutrition.(1) creatine concentration in muscle (lg/mg wet weight of muscle) Skeletal muscle is the major component of lean body mass and is also the largest protein reservoir in the body. However, there is no accurate method for measuring muscle mass in man. A limited number of whole body dissection studies have been performed in relatively well nourished and in severely malnourished children (16,18,27). This direct method has limitations because it is difficult to ensure complete dissection of all muscle tissue, variable amounts of water and other fluids are lost during and after dissection, and studies are done a t varying times after death. It is therefore difficult to extrapolate these findings to the dynamic situation in the living individual. Of the alternative and indirect methods of estimating muscle mass, that based on the 24-hr creatinine excretion is most widely used. The strong association between creatinine excretion and body weight led to the suggestion that muscle mass could ...