Recently, Scientists from University of Illinois investigated whether or not leucine and/or carbohydrate ingestion would prolong the elevation of protein synthesis after a high protein meal in Sprague Dawley rats. In this study, rats were trained to eat 3 times per day and then food deprived for 12 hours. After fasting, they were given a test meal that consisted of 20% whey protein. At 135 minutes post-feeding the rats ingested either 2.36 g of glucose and sucrose or 270 mg of leucine (dissolved in water) or a combination of the two. Tissues and blood were analyzed at time 0 (food deprived) and at 90 and 180 minutes post-feeding for muscle protein synthesis and markers of cellular energy status. The researchers reported that rats who were fed carbohydrates and/or leucine supplements 135 minutes after a meal extended the postprandial "anabolic window".
Wilson GJ, Layman DK, Moulton CJ, Norton LE, Anthony TG, Proud CG, Rupassara SI, Garlick PJ. Leucine or carbohydrate supplementation reduces AMPK and eEF2 phosphorylation and extends postprandial muscle protein synthesis in rats. Am J Physiol Endocrinol Metab. 2011 Sep 13. [Epub ahead of print]