Muscle Protein Synthesis Rates After Protein Consumption in Lean, Overweight, and Obese Adults

There are an increasing number of individuals in the United States with obesity, and this is a major health concern with links to many chronic diseases. Impairments in protein metabolism with obesity may disrupt muscle function and modify the dietary protein requirements in obese individuals. Further, overweight and obese type 2 diabetics exhibit dramatically reduced skeletal muscle mass compared with lean, healthy controls. Surprisingly, the influence of being overweight or obese on this decline in muscle mass remains understudied, despite clear evidence that similar metabolic impairments typically exist in these populations prior to the development of overt diabetes. Protein ingestion provides the amino acid building blocks to synthesize and repair muscle proteins in adults. Previous research has shown that the muscle protein synthetic response to food ingestion may be reduced in overweight/obese adults. However, this research provided the 'free' amino acids in small portions every 15 min during the postprandial period. In free living conditions, however, it is more common to consume protein dense foods in single portions. Currently, there is no information available on how eating protein rich foods affects muscle protein synthesis in overweight and obese adults. This proposed research will fill this research gap by being the first study to compare the muscle protein synthetic response to the ingestion of a meal-like amount of high quality protein in lean, overweight and obese adults. The objective of this study is to determine the muscle protein synthetic response after the consumption of 35g pork protein in lean, overweight and obese adults. In order to assess this objective the researchers propose to use primed continuous infusion of L-\[ring-13C6\] phenylalanine to measure muscle protein synthesis rates after the consumption of dietary protein. In a parallel design the researchers will study 13 obese (BMI 30-39.9 kg/m2) participants, 13 overweight (BMI 25-29.9