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Impact of Whey and Soy Protein Ingestion in Conjunction With Energy Restriction in Overweight/Obese Individuals

This study has been completed.
Information provided by (Responsible Party):
Stuart M. Phillips, McMaster University Identifier:
First received: August 4, 2011
Last updated: June 6, 2015
Last verified: June 2015
It is known that dieting (restricted energy intake) without resistance training leads to a reduced metabolic rate, and the loss of both fat and muscle mass. When exercise is not included in a period of restricted energy intake, the degree to which muscle mass is lost is highly dependent upon protein consumption. Whey protein is a high quality protein isolated from milk and is known to stimulate new protein synthesis for all proteins in your body. Previous research has established that the consumption of whey protein has been correlated with retaining muscle mass while stimulating fat loss. However, the mechanisms behind these findings is still unknown. The purpose of this study is to establish a mechanistic underpinning to the efficacy of whey protein versus soy protein and a carbohydrate control (maltodextrin), in promoting fat mass loss and lean mass retention during a period of short-term controlled dietary energy deficit (-750 kcalories/day).

Condition Intervention
Behavioral: Weight loss
Dietary Supplement: Soy
Dietary Supplement: Whey

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Double Blind (Participant, Investigator)
Primary Purpose: Treatment
Official Title: Molecular Events Underpinning Changes in Tissue Metabolism With Whey and Soy Ingestion in Energy Restriction in Overweight/Obese Adults

Further study details as provided by Stuart M. Phillips, McMaster University:

Primary Outcome Measures:
  • Muscle protein synthesis rate and lipolytic rate as measured using stable isotope and glycerol infusions. [ Time Frame: After 14 day dietary intervention ]

Secondary Outcome Measures:
  • Transcriptomic changes (via gene profiling) associated with the effects of whey on lipogenic and lipid oxidative genes, and protein synthetic pathways in muscle. [ Time Frame: After 14 days of dietary intervention ]

Enrollment: 42
Study Start Date: February 2012
Study Completion Date: May 2013
Primary Completion Date: February 2013 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Placebo Comparator: Control
Carbohydrate & 750 kcal dietary restriction while they receive a daily supplement (2 x 25 g) of maltodextrin (no protein) for 14 days. Weight loss.
Behavioral: Weight loss
Experimental: Whey
Whey protein & 750 kcal dietary restriction while they receive a daily supplement (2 x 25 g) of WPI for 14 days. Weight loss.
Behavioral: Weight loss
Dietary Supplement: Whey
2 x 25g/d WPI
Experimental: Soy
Soy protein & 750 kcal dietary restriction while they receive a daily supplement (2 x 25 g) of SPC for 14 days. Weight loss.
Behavioral: Weight loss
Dietary Supplement: Soy
2 x 25g/d SPC


Ages Eligible for Study:   35 Years to 65 Years   (Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • Aged 35 to 55 years old
  • Moderately Obese/Overweight (body mass index > 25 and < 42 kg/m2)
  • Healthy
  • Non-smoker

Exclusion Criteria:

  • Suffer from type 2 diabetes, hyperlipidemia, or thyroid dysfunction
  • Taking medications
  • Having an unstable weight in the past 4-6 months, or dieting at some time during the past 6 months
  • Taking weight loss products or aids (including energy drinks)
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Please refer to this study by its identifier: NCT01530646

Canada, Ontario
McMaster University
Hamilton, Ontario, Canada
Sponsors and Collaborators
McMaster University
Principal Investigator: Stuart Phillips, Ph.D. Department of Kinesiology, McMaster University
  More Information

Additional Information:
Publications automatically indexed to this study by Identifier (NCT Number):
Responsible Party: Stuart M. Phillips, Professor, McMaster University Identifier: NCT01530646     History of Changes
Other Study ID Numbers: 11-999
Study First Received: August 4, 2011
Last Updated: June 6, 2015

Keywords provided by Stuart M. Phillips, McMaster University:
muscle protein synthesis
muscle protein breakdown
caloric restriction

Additional relevant MeSH terms:
Body Weight
Signs and Symptoms processed this record on May 25, 2017