The influence of meal frequency on change of body weight and protein status, measured by level of amino acid oxidation (decarboxylation) in the postabsorptive state, was studied at a fixed daily protein intake. Growing rats (250g) were fed through gastric canula a feeding solution based on Nutrison Standard supplying 1.6g protein and 266kJ ME daily. This amount was given in either 2 large meals at the beginning and the end, or in 6 smaller meals, or by continuous infusion during entire dark period (10 hrs). After 3 weeks of feeding the mean growth rate of the rats fed continuously was nearly 20% higher than rats fed the same amount in 2 meals. The rats fed 6 meals a day had a growth rate rather similar to the rats fed continuously. The percentile recovery of label as 14CO2 in the breath after an intraperitoneal injection of [1-14C]leucine (4 hrs after last meal) was significantly higher (p.05) for the animals fed continuously (27% sd 2.6) compared to the rats fed 2 meals (21.9% sd 4.0). The value for 6 meal group was intermediate (24.5 sd 1.8). The results indicate that the metabolic utilization of a fixed daily amount of protein is clearly influenced by the way of supply. With respect to the change of body weight and protein status, animals have more benefit of the same amount of protein if the supply is more equable. It is suggested that the difference is caused by metabolic restriction for an adequate utilisation of large meals. Therefore large meals are supposed to cause a waste of amino acids in the postprandial phase. As a consequence amino acid amount that will be stored in the body to be available in the postabsorptive phase will be less.