Diet X Genotype Study

This study is currently recruiting participants. (see Contacts and Locations)
Verified April 2013 by Stanford University
Information provided by (Responsible Party):
Christopher Gardner, Stanford University Identifier:
First received: March 27, 2013
Last updated: April 3, 2013
Last verified: April 2013

Genomics research is advancing rapidly, and links between genes and obesity continue to be discovered and better defined. A growing number of single nucleotide polymorphisms (SNPs) in multiple genes have been shown to alter an individual's response to dietary macronutrient composition. Based on prior genetic studies evaluating the body's physiological responses to dietary carbohydrates or fats, the investigators identified multi-locus genotype patterns with SNPs from three genes (FABP2, PPARG, and ADRB2): a low carbohydrate-responsive genotype (LCG) and a low fat-responsive genotype (LFG). In a preliminary, retrospective study (using the A TO Z weight loss study data), the investigators observed a 3-fold difference in 12-month weight loss for initially overweight women who were determined to have been appropriately matched vs. mismatched to a low carbohydrate (Low Carb) or low fat (Low Fat) diet based on their multi-locus genotype pattern. The primary objective of this study is to confirm and expand on the preliminary results and determine if weight loss success can be increased if the dietary approach (Low Carb vs. Low Fat) is appropriately matched to an individual' s genetic predisposition (Low Carb Genotype vs. Low Fat Genotype) toward those diets.

Condition Intervention
Insulin Resistance
Behavioral: Low-Carbohydrate Diet
Behavioral: Low-Fat Diet

Study Type: Interventional
Study Design: Allocation: Randomized
Endpoint Classification: Efficacy Study
Intervention Model: Parallel Assignment
Masking: Double Blind (Investigator, Outcomes Assessor)
Primary Purpose: Treatment
Official Title: Do Genotype Patterns Predict Weight Loss Success for Low Carb vs. Low Fat Diets?

Further study details as provided by Stanford University:

Primary Outcome Measures:
  • Change from baseline in weight at 12 months [ Time Frame: Baseline, 3 months, 6 months, 12 months ] [ Designated as safety issue: No ]

Secondary Outcome Measures:
  • Change from baseline in fasting insulin at 12 months [ Time Frame: Baseline, 6 months, 12 months ] [ Designated as safety issue: No ]
  • Change from baseline in glucose at 12 months [ Time Frame: Baseline, 6 months, 12 months ] [ Designated as safety issue: No ]
  • Genotype (low-fat or low-carb) [ Time Frame: Baseline ] [ Designated as safety issue: No ]
  • Change from baseline in energy expenditure at 12 months [ Time Frame: Baseline, 6 months, 12 months ] [ Designated as safety issue: No ]
  • Change from baseline in lipids at 12 months [ Time Frame: Baseline, 3 months, 6 months, 12 months ] [ Designated as safety issue: No ]
    Total Cholesterol LDL Cholesterol HDL Cholesterol Triglycerides

Estimated Enrollment: 400
Study Start Date: March 2013
Estimated Study Completion Date: December 2016
Estimated Primary Completion Date: December 2016 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: Experimental: Low-Carbohydrate Diet
Healthy, Low-Carbohydrate Diet
Behavioral: Low-Carbohydrate Diet
Counseling/instruction on how to follow a low-carbohydrate diet.
Experimental: Experimental: Low-Fat Diet
Healthy, Low-Fat Diet
Behavioral: Low-Fat Diet
Counseling/instruction on how to follow a low-fat diet.

Detailed Description:

If the intriguing preliminary retrospective results are confirmed in this full scale study, the results will demonstrate that inexpensive DNA testing could help dieters predict whether they will have greater weight loss success on a Low Carb or a Low Fat diet. Commensurate with increasing scientific interest in personalized medicine approaches to intervention development, this would provide an example of the potentially substantial health impacts that could be obtained through understanding specific gene-environment interactions that have been anticipated from the unraveling of the human genome.


Ages Eligible for Study:   18 Years to 50 Years
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • Age: > 18 years of age
  • Women: Pre-menopausal (self-report) and <50 years of age
  • Men: <50 years of age
  • Race/Ethnicity: Caucasian only
  • BMI (body mass index): 27-40 kg/m2 (need to lose >10% body weight to achieve healthy BMI)
  • Body weight stable for the last two months, and not actively on a weight loss plan
  • No plans to move from the area over the next two years
  • Available and able to participate in the evaluations and intervention for the study period
  • Willing to accept random assignment
  • To enhance study generalizability, people on medications not noted below as specific exclusions can
  • participate if they have been stable on such medications for at least three months
  • Ability and willingness to give written informed
  • No known active psychiatric illness

Exclusion Criteria:

Subjects with the following conditions will be excluded (determined by self-report):

  • Pregnant, lactating, within 6 months post-partum, or planning to become pregnant in the next 2 years
  • Diabetes (type 1 and 2) or history of gestational diabetes or on hypoglycemic medications for any other indication
  • Prevalent diseases: Malabsorption, renal or liver disease, active neoplasms, recent myocardial infarction (<6 months)(patient self-report and, if available, review of labs from primary care provider)
  • Smokers (because of effect on weight and lipids)
  • History of serious arrhythmias, or cerebrovascular disease
  • Uncontrolled hyper- or hypothyroidism (TSH not within normal limits)
  • Medications: Lipid lowering, antihypertensive medications, and those known to affect weight/energy expenditure
  • Excessive alcohol intake (self-reported, >3 drinks/day)
  • Musculoskeletal disorders precluding regular physical activity
  • Unable to follow either of the two study diets for reasons of food allergies or other (e.g., vegan)
  • Currently under psychiatric care, or taking psychiatric medications
  • Inability to communicate effectively with study personnel
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its identifier: NCT01826591

Contact: Antonella Dewell, MS, RD 650-736-8577

United States, California
Stanford University School of Medicine Recruiting
Stanford, California, United States, 94305
Contact: Antonella Dewell, MS, RD    650-736-8577   
Principal Investigator: Christopher D Gardner, PhD         
Sponsors and Collaborators
Stanford University
Principal Investigator: Christopher D Gardner, PhD Stanford University
  More Information

Additional Information:
No publications provided

Responsible Party: Christopher Gardner, Associate Professor of Medicine, Stanford University Identifier: NCT01826591     History of Changes
Other Study ID Numbers: 22305
Study First Received: March 27, 2013
Last Updated: April 3, 2013
Health Authority: United States: Institutional Review Board processed this record on March 26, 2015