Comparison of Popular Weight Loss Diets
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ClinicalTrials.gov Identifier: NCT00079573 |
Recruitment Status :
Completed
First Posted : March 10, 2004
Last Update Posted : August 18, 2006
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Condition or disease | Intervention/treatment | Phase |
---|---|---|
Obesity | Behavioral: Atkins diet (extremely low carbohydrate) Behavioral: Zone diet (low carbohydrate, high protein) Behavioral: Ornish diet (very low fat) | Phase 2 |
Obesity is the single most significant, nutrition-related health issue of the new millennium. Several "medical experts" have designed and promoted weight loss diets that dramatically differ from one another and from the USDA Dietary Guidelines. These diets have gained surprisingly widespread and persistent popularity among Americans despite the lack of evidence supporting their claims. This clinical trial will provide preliminary feasibility data for a full-scale study that will examine health outcomes (e.g., benefits, risks, success) of three popular weight loss diets. The study will investigate behavioral and physiological factors that influence adherence and retention to these diet plans.
Overweight women will be randomly assigned to one of four diets for 1 year: Atkins (extremely low carbohydrate), Zone (low carbohydrate, high protein), Ornish (very low fat), or USDA/Food Pyramid (high carbohydrate/moderate-low fat). Behavioral and physiological data will be collected. Participants attend study visits at baseline, 8 weeks, 6 months, and 1 year. At these visits, measurements will include that will include weight and blood pressure measurements and blood tests. Participants will be asked to complete ten questionnaires over the course of the study to assess behavior and appetite. Participants will also undergo a DEXA scan to assess body composition.
Study Type : | Interventional (Clinical Trial) |
Enrollment : | 300 participants |
Allocation: | Randomized |
Intervention Model: | Parallel Assignment |
Masking: | Single |
Primary Purpose: | Treatment |
Official Title: | Benefits & Risks of Popular Weight Loss Diets |
Study Start Date : | July 2002 |
Study Completion Date : | June 2004 |

- Weight; measured at each study visit
- Percent body fat; measured at each study visit
- Blood lipids (cholesterol, triglycerides); measured at each study visit
- Fasting insulin and glucose; measured at each study visit
- Behavioral variables; measured at each study visit

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Ages Eligible for Study: | 30 Years to 50 Years (Adult) |
Sexes Eligible for Study: | Female |
Accepts Healthy Volunteers: | Yes |
Inclusion Criteria
- Body mass index (BMI) between 27 and 40 kg/m2
- Weight stable for last 2 months
- Not actively on a weight loss plan
- No plans to move from the area over the next 2 years
- Willing to accept random assignment
Exclusion Criteria
- Pregnant or breastfeeding
- Within 6 months of giving birth or planning to become pregnant in the next 2 years
- Diabetes (type 1 or 2) or history of gestational diabetes
- Renal or liver disease, active neoplasms, or recent myocardial infarction
- Hyper- or hypothyroidism
- Lipid lowering medications or medications known to affect weight/energy expenditure
- Excessive alcohol intake (self-reported, > 3 drinks/day)
- Postmenopausal, including surgical menopause
- Currently under psychiatric care or severely clinically depressed (> 17 on Beck Inventory)

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.
Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT00079573
United States, California | |
Stanford Prevention Research Center | |
Stanford, California, United States, 94305 |
Principal Investigator: | Christopher D. Gardner, PhD | Stanford University |
Publications automatically indexed to this study by ClinicalTrials.gov Identifier (NCT Number):
ClinicalTrials.gov Identifier: | NCT00079573 |
Other Study ID Numbers: |
R21AT001098-01A1 ( U.S. NIH Grant/Contract ) |
First Posted: | March 10, 2004 Key Record Dates |
Last Update Posted: | August 18, 2006 |
Last Verified: | August 2006 |
Weight Loss Obesity Overweight Premenopausal women Diet |
Weight Loss Body Weight Body Weight Changes |