Plasma concentrations of free amino acids during 3 weeks treatment of massively obese children with a very low calorie diet.

Eight grossly obese children (2 girls, 8 boys, age 12.6 +/- 2.1 mean +/- SD years, mean overweight 73.3 +/- 14%) were treated for 3 weeks with a very low calorie diet (VLCD), containing 1022 kJ/240 kcal, 33 g protein, 25.5 g carbohydrate and 0.7 g fat/day. Mean weight loss after 3 weeks was 9.47 +/- 2.8 kg and mean nitrogen loss was calculated to be 113.3 +/- 71.2 g. While serum electrolytes, enzymes, glucose, urea and creatinine remained almost unchanged, distinct alterations of 23 free amino acids in plasma could be observed. A transient increase of plasma valine, leucine, isoleucine and alpha-aminobutyrate during the 1st week was followed by a constant fall in the 2nd and 3rd week. Glycine, proline, serine and threonine showed a progressive increase, while cystine, histidine and, above all, alanine decreased, the diminution of alanine being most rapid during the 1st week. No significant changes were observed in plasma concentrations of arginine, asparagine, aspartic acid, citrulline, glutamic acid, glutamine, lysine, tyrosine, ornithine, phenylalanine and taurine. Total plasma amino acid content did not change during diet compared to the pre-diet period. The behavior of plasma amino acids shows a typical pattern within four groups, reflecting various interorgan substrate fluxes during hypocaloric dieting.