Plasma amino acids changes in obese patients on very low-calorie diets.

The reduced feeling of hunger alleged by obese patients on very low-calorie diets (VLCD) could be supposed due to restoration to a normal level of plasma TRP:LNAA ratio, previously found lowered in these subjects. We tested this hypothesis measuring weekly the changes of plasma amino acid concentration in obese individuals who followed a 5 week slimming regimen consisting in a powdered formula diet (500 kcal/d). A decrease in plasma TRP:LNAA ratio was seen, since tryptophan decreased, whereas valine and isoleucine increased over time. An increase in plasma lysine, threonine, glycine and aminobutyrate was also observed. The early decrease shown by alanine and glutamate was followed by an increase in the last weeks of the study. Our hypothesis was not confirmed, since VLCD failed to carry back the plasma TRP:LNAA ratio to a normal level.