Albumin and labile-protein serum concentrations during very-low-calorie diets with different compositions

Circulating concentrations of albumin and the labile proteins prealbumin (PA) and retinol-binding protein (RBP) were evaluated over 20 d in five groups of obese patients. The patients were given four types of very-low-calorie diets (VLCDs) (less than 500 kcal/d) that provided different amounts of protein or carbohydrate (CHO) plus protein and a conventional 1200-kcal/d hypocaloric diet. Serum albumin concentrations did not vary significantly during any of the diets whereas PA and RBP remained unchanged only during the conventional 1200-kcal/d diet. Similar and significant decreases of serum PA and RBP were observed during the VLCDs studied. The molar ratio of RBP to PA did not vary during dieting. Thus, when less than 500 kcal/d are given, changes of serum short-half-life visceral proteins are not affected by either the addition of CHO to protein or the changes in protein intake. Moreover, serum albumin concentration and RBP/PA do not vary during VLCDs.