Anabolic sensitivity of postprandial muscle protein synthesis to the ingestion of a protein-dense food is reduced in overweight and obese young adults.
Excess body fat diminishes muscle protein synthesis rates in response to hyperinsulinemic-hyperaminoacidemic clamps. However, muscle protein synthetic responses after the ingestion of a protein-dense food source across a range of body mass indexes (BMIs) have not been compared.



We compared the myofibrillar protein synthetic response and underlying nutrient-sensing mechanisms after the ingestion of lean pork between obese, overweight, and healthy-weight adults.



Ten healthy-weight [HW; BMI (in kg/m2): 22.7 ± 0.4], 10 overweight (OW; BMI: 27.1 ± 0.5), and 10 obese (OB; BMI: 35.9 ± 1.3) adults received primed continuous l-[ring-13C6]phenylalanine infusions. Blood and muscle biopsy samples were collected before and after the ingestion of 170 g pork (36 g protein and 3 g fat) to assess skeletal muscle anabolic signaling, amino acid transporters [large neutral and small neutral amino acid transporters (LAT1, SNAT2) and CD98], and myofibrillar protein synthesis.



At baseline, OW and OB groups showed greater relative amounts of mammalian target of rapamycin complex 1 (mTORC1) protein than the HW group. Pork ingestion increased mTORC1 phosphorylation only in the HW group (P = 0.001). LAT1 and SNAT2 protein content increased during the postprandial period in all groups (time effect, P < 0.05). Basal myofibrillar protein synthetic responses were similar between groups (P = 0.43). However, myofibrillar protein synthetic responses (0-300 min) were greater in the HW group (1.6-fold; P = 0.005) after pork ingestion than in the OW and OB groups.



There is a diminished myofibrillar protein synthetic response to the ingestion of protein-dense food in overweight and obese adults compared with healthy-weight controls. These data indicate that impaired postprandial myofibrillar protein synthetic response may be an early defect with increasing fat mass, potentially dependent on altered anabolic signals, that reduces muscle sensitivity to food ingestion. This trial was registered at clinicaltrials.gov as NCT02613767.
Division of Nutritional Sciences.
Joseph W
JW
Beals
Department of Kinesiology and Community Health.
Richard A
RA
Sukiennik
Department of Kinesiology and Community Health.
Julian
J
Nallabelli
Department of Kinesiology and Community Health.
Russell S
RS
Emmons
Department of Kinesiology and Community Health.
Stephan
S
van Vliet
Department of Kinesiology and Community Health.
Justin R
JR
Young
Roy J Carver Biotechnology Center, and.
Alexander V
AV
Ulanov
Roy J Carver Biotechnology Center, and.
Zhong
Z
Li
Department of Family Medicine, University of Illinois at Urbana-Champaign, Urbana, IL.
Scott A
SA
Paluska
Division of Nutritional Sciences, Department of Kinesiology and Community Health.
Michael
M
De Lisio
Division of Nutritional Sciences, Department of Kinesiology and Community Health, naburd@illinois.edu.
Nicholas A
NA
Burd
D000273:Adipose Tissue / Q000378:metabolism*; D050154:Adiposity; D000328:Adult; D026905:Amino Acid Transport Systems / Q000378:metabolism; D000818:Animals; D015992:Body Mass Index; D004032:Diet; D004044:Dietary Proteins / Q000378:metabolism*; D002149:Energy Intake; D005260:Female; D006801:Humans; D008297:Male; D000076222:Mechanistic Target of Rapamycin Complex 1; D046912:Multiprotein Complexes / Q000378:metabolism; D009124:Muscle Proteins / Q000378:metabolism*; D018482:Muscle, Skeletal / Q000378:metabolism*; D009765:Obesity / Q000378:metabolism*; D050177:Overweight; D019518:Postprandial Period; D014176:Protein Biosynthesis / Q000187:drug effects*; D000069466:Red Meat; D012016:Reference Values; D013552:Swine; D058570:TOR Serine-Threonine Kinases / Q000378:metabolism; D055815:Young Adult
D026905:Amino Acid Transport Systems; D004044:Dietary Proteins; D046912:Multiprotein Complexes; D009124:Muscle Proteins; D000076222:Mechanistic Target of Rapamycin Complex 1; D058570:TOR Serine-Threonine Kinases
amino acid transporters; inflammation; insulin resistance; leucine; mTORC1; muscle mass