This study was undertaken to determine whether the protein feeding pattern could induce chronic adaptation of protein turnover. After a 15-day adaptive period, elderly (68 yr) and young (26 yr) women received, for 14 days, a diet providing 200 KJ x kg fat-free mass (FFM)(-1) x day(-1), where the daily protein intake (1.7 g protein x kg FFM(-1) x day(-1)) was either spread over 4 meals in the spread pattern or mainly (80%) consumed at noon in the pulse pattern. One day after the end of the dietary treatment, whole body leucine kinetics were measured by use of a continuous [(13)C]leucine infusion, both in the postabsorptive state and in the same fed state. The pulse pattern was able to induce, in young as in elderly women, a lower postabsorptive leucine oxidation and endogenous leucine flux than the spread pattern and improved the responsiveness of nonoxidative leucine disposal during 4-h oral feeding. Thus the pulse pattern was able to induce chronic regulation of protein metabolism in young as in elderly women.