Study Results
The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.
Basic Information
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COMPLETED
NA
100 participants
INTERVENTIONAL
2015-08-31
2017-06-30
Brief Summary
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Detailed Description
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This project is a study to investigate the effects of a walnut-enriched vs. standard reduced-energy diet on body weight and satiety via pre- and post-meal ratings scales, as well as exploring the response of satiety- and appetite-related gastrointestinal peptides to meals with or without walnuts in a sample subset.
The specific aims of this study are:
1. To compare the effects of a walnut-enriched reduced-energy diet to a standard reduced-energy diet on body weight and cardiovascular disease risk factors in a sample of overweight and obese adults in an intensive 6-month weight loss intervention.
2. To examine whether there is a differential response in satiety- and appetite-related ratings scales in association with a walnut-enriched reduced-energy diet and a standard reduced-energy diet among the participants in this weight-loss study.
3. To examine the response of satiety- and appetite-related gastrointestinal peptides (ghrelin, cholecystokinin, glucagon-like peptide, and peptide YY), to meals with or without walnuts in a sample subset, as an exploratory aim.
The first two aims will be addressed in a randomized controlled study involving 100 overweight or obese men and women assigned to a walnut-enriched reduced-energy diet or a standard reduced-energy diet in the context of a 6-month intensive weight loss intervention. Subjective satiety- and appetite-related ratings will be collected at specific intervals before lunch and dinner using visual analogue scales. Postprandial gastrointestinal peptide response to a meal with or without walnuts, the third and exploratory aim, will be measured in a subset of study participants (n=20) using a within-subject crossover study design.
The investigators hypothesize that participants assigned to the walnut-enriched diet study arm will have greater weight loss and overall better improvements in cardiovascular disease risk factors, and that ratings of hunger, fullness, and anticipated prospective consumption will differ from those of participants assigned to the standard reduced-energy diet. The investigators hypothesize that postprandial satiety- and appetite-related gastrointestinal peptides, which play a role in short-term control of appetite and may be biomarkers of satiety, may differ in response to different isocaloric meal composition. Results from this study will contribute to understanding the role of nuts in weight control, including further knowledge of the explanatory mechanisms, and will expand knowledge of how nuts in the diet may contribute to the prevention and management of obesity.
Conditions
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Keywords
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Study Design
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RANDOMIZED
PARALLEL
TREATMENT
NONE
Study Groups
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Walnut-rich weight loss diet arm
Participants will have an individualized reduced-calorie diet prescription and weight loss counseling session with the project coordinator, who is a registered dietitian. Composition of prescribed diets will be based on individual preferences. During the 6-month intervention, study subjects will participate in individualized counseling and group sessions, with in-person, telephone, email and text message contacts to provide support and behavioral guidance and strategies. All participants will have contact with the project coordinator a minimum of every 1-2 weeks. Walnuts will be provided to participants in the walnut-rich study arm.
Walnut-rich weight loss diet
Composition of prescribed diets will be based on individual preferences, with the goal of reduced energy intake and increased energy expenditure. During the 6-month intervention, study subjects will participate in individualized counseling and group sessions, with in-person, telephone, email and text message contacts to provide support and behavioral guidance and strategies. Walnuts will be provided to participants. The overall content of the intervention consists of key elements of cognitive-behavioral therapy for obesity. The physical activity component emphasizes planned aerobic exercise, increased physical activity in the lifestyle, and strength training.
Standard weight loss diet arm
Participants will have an individualized reduced-calorie diet prescription and weight loss counseling session with the project coordinator, who is a registered dietitian. Composition of prescribed diets will be based on individual preferences. During the 6-month intervention, study subjects will participate in individualized counseling and group sessions, with in-person, telephone, email and text message contacts to provide support and behavioral guidance and strategies. Participants assigned to this arm will be instructed to abstain from the consumption of nuts during the study. All participants will have contact with the project coordinator a minimum of every 1-2 weeks.
Standard weight loss diet
Composition of prescribed diets will be based on individual preferences, with the goal of reduced energy intake and increased energy expenditure. During the 6-month intervention, study subjects will participate in individualized counseling and group sessions, with in-person, telephone, email and text message contacts to provide support and behavioral guidance and strategies. The overall content of the intervention consists of key elements of cognitive-behavioral therapy for obesity. The physical activity component emphasizes planned aerobic exercise, increased physical activity in the lifestyle, and strength training.
Interventions
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Walnut-rich weight loss diet
Composition of prescribed diets will be based on individual preferences, with the goal of reduced energy intake and increased energy expenditure. During the 6-month intervention, study subjects will participate in individualized counseling and group sessions, with in-person, telephone, email and text message contacts to provide support and behavioral guidance and strategies. Walnuts will be provided to participants. The overall content of the intervention consists of key elements of cognitive-behavioral therapy for obesity. The physical activity component emphasizes planned aerobic exercise, increased physical activity in the lifestyle, and strength training.
Standard weight loss diet
Composition of prescribed diets will be based on individual preferences, with the goal of reduced energy intake and increased energy expenditure. During the 6-month intervention, study subjects will participate in individualized counseling and group sessions, with in-person, telephone, email and text message contacts to provide support and behavioral guidance and strategies. The overall content of the intervention consists of key elements of cognitive-behavioral therapy for obesity. The physical activity component emphasizes planned aerobic exercise, increased physical activity in the lifestyle, and strength training.
Eligibility Criteria
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Inclusion Criteria
* BMI \>27.0 kg/m2 and \<40 kg/m2
* non-smoker
* willing and able to participate in clinic visits, group sessions, telephone, and internet communications at specified intervals
* able to provide data through questionnaires and by telephone
* willing to maintain contact with the investigators for 6 months
* willing to allow blood collections
* no known allergy to tree nuts
* capable of performing a simple test for assessing cardiopulmonary fitness
Exclusion Criteria
* a history or presence of a comorbid diseases for which diet modification and increased physical activity may be contraindicated
* smoker
* self-reported pregnancy or breastfeeding or planning a pregnancy within the next year
* currently actively involved in another diet intervention study or organized weight loss program
* a history or presence of a significant psychiatric disorder or any other condition that, in the investigator's judgement, would interfere with participation in the trial
21 Years
75 Years
ALL
Yes
Sponsors
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AICR Matching Grant Program (California Walnut Commission and AICR)
UNKNOWN
University of California, San Diego
OTHER
Responsible Party
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Cheryl Rock
Professor
Principal Investigators
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Cheryl L. Rock, PhD, RD
Role: PRINCIPAL_INVESTIGATOR
University of California, San Diego
Locations
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UC San Diego
La Jolla, California, United States
Countries
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References
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Other Identifiers
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20154971
Identifier Type: -
Identifier Source: org_study_id