title: Whey protein supplementation during resistance training augments lean body mass.
abstract: Compared to soy, whey protein is higher in leucine, absorbed quicker and results in a more pronounced increase in muscle protein synthesis.
  
  
  OBJECTIVE
  To determine whether supplementation with whey promotes greater increases in muscle mass compared to soy or carbohydrate, we randomized non-resistance-trained men and women into groups who consumed daily isocaloric supplements containing carbohydrate (carb; n = 22), whey protein (whey; n = 19), or soy protein (soy; n = 22).
  
  
  METHODS
  All subjects completed a supervised, whole-body periodized resistance training program consisting of 96 workouts (~9 months). Body composition was determined at baseline and after 3, 6, and 9 months. Plasma amino acid responses to resistance exercise followed by supplement ingestion were determined at baseline and 9 months.
  
  
  RESULTS
  Daily protein intake (including the supplement) for carb, whey, and soy was 1.1, 1.4, and 1.4 g·kg body mass⁻¹, respectively. Lean body mass gains were significantly (p < 0.05) greater in whey (3.3 ± 1.5 kg) than carb (2.3 ± 1.7 kg) and soy (1.8 ± 1.6 kg). Fat mass decreased slightly but there were no differences between groups. Fasting concentrations of leucine were significantly elevated (20%) and postexercise plasma leucine increased more than 2-fold in whey. Fasting leucine concentrations were positively correlated with lean body mass responses.
  
  
  CONCLUSIONS
  Despite consuming similar calories and protein during resistance training, daily supplementation with whey was more effective than soy protein or isocaloric carbohydrate control treatment conditions in promoting gains in lean body mass. These results highlight the importance of protein quality as an important determinant of lean body mass responses to resistance training.
authors.affiliation: a The Human Performance Laboratory, Department of Kinesiology , University of Connecticut , Storrs , CT.
authors.forename: Jeff S
authors.initials: JS
authors.lastname: Volek
authors.forename: Brittanie M
authors.initials: BM
authors.lastname: Volk
authors.forename: Ana L
authors.initials: AL
authors.lastname: Gómez
authors.forename: Laura J
authors.initials: LJ
authors.lastname: Kunces
authors.forename: Brian R
authors.initials: BR
authors.lastname: Kupchak
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Freidenreich
authors.forename: Juan C
authors.initials: JC
authors.lastname: Aristizabal
authors.forename: Catherine
authors.initials: C
authors.lastname: Saenz
authors.forename: Courtenay
authors.initials: C
authors.lastname: Dunn-Lewis
authors.forename: Kevin D
authors.initials: KD
authors.lastname: Ballard
authors.forename: Erin E
authors.initials: EE
authors.lastname: Quann
authors.forename: Diana L
authors.initials: DL
authors.lastname: Kawiecki
authors.forename: Shawn D
authors.initials: SD
authors.lastname: Flanagan
authors.forename: Brett A
authors.initials: BA
authors.lastname: Comstock
authors.forename: Maren S
authors.initials: MS
authors.lastname: Fragala
authors.forename: Jacob E
authors.initials: JE
authors.lastname: Earp
authors.forename: Maria L
authors.initials: ML
authors.lastname: Fernandez
authors.forename: Richard S
authors.initials: RS
authors.lastname: Bruno
authors.forename: Adam S
authors.initials: AS
authors.lastname: Ptolemy
authors.forename: Mark D
authors.initials: MD
authors.lastname: Kellogg
authors.forename: Carl M
authors.initials: CM
authors.lastname: Maresh
authors.forename: William J
authors.initials: WJ
authors.lastname: Kraemer
mesh_terms: D000328:Adult; D000596:Amino Acids / Q000097:blood; D015992:Body Mass Index; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004044:Dietary Proteins / Q000008:administration & dosage; D019587:Dietary Supplements; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007930:Leucine / Q000097:blood; D008297:Male; D008894:Milk Proteins / Q000008:administration & dosage*; D009124:Muscle Proteins / Q000096:biosynthesis; D018482:Muscle, Skeletal / Q000187:drug effects / Q000378:metabolism; D011446:Prospective Studies; D055070:Resistance Training; D030262:Soybean Proteins / Q000008:administration & dosage; D000067816:Whey Proteins; D055815:Young Adult
chemical_list: D000596:Amino Acids; D004040:Dietary Carbohydrates; D004044:Dietary Proteins; D008894:Milk Proteins; D009124:Muscle Proteins; D030262:Soybean Proteins; D000067816:Whey Proteins; D007930:Leucine