Comparison of Two Different Diets on Health Outcomes

Effect of a Low-Carbohydrate and High-Carbohydrate, High-Fiber Diet on Insulin Sensitivity and Risk Markers for Cardiovascular Disease in Men and Women With the Metabolic Syndrome

The purpose of this study is to compare the effects of a low-carbohydrate diet and a high-carbohydrate, high-fiber diet, on insulin sensitivity and blood chemicals considered risk markers for heart disease, in persons with the metabolic syndrome.

Our primary hypothesis is that the ad libitum high-carbohydrate, high-fiber diet will significantly improve insulin sensitivity, whereas the ad libitum low-carbohydrate, low-fiber diet will not.

Study Overview

• Status: Unknown
• Conditions: Metabolic Syndrome X
• Intervention / Treatment: Behavioral: Low-carbohydrate and high-carbohydrate diets

Detailed Description

Low-carbohydrate eating is becoming perceived as more than just a weight loss diet, but rather a means to improve health. Several studies have been published suggesting that low-carbohydrate diets may be preferable to low-fat diets for weight loss and in terms of some health markers. On the other hand, considerable evidence suggests that low-carbohydrate diets, high in fat, are associated with a number of adverse health outcomes. The health benefits of high-carbohydrate, high-fiber diets have also been demonstrated. This study is designed to assess the differences between the two different dietary strategies in terms of a number of health outcomes. Participants will consume, in random order, a non-calorie-restricted low-carbohydrate and a non-calorie-restricted high-carbohydrate, high-fiber diet for one month, with a 4-6 week washout period in between.

• Study Type: Interventional
• Enrollment (Anticipated): 24
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Virginia
    • Charlottesville, Virginia, United States, 22904
      • University of Virginia General Clinical Research Center

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years to 64 years (Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

Description

Inclusion Criteria:

1. Subjects must meet the criteria of the metabolic syndrome, which is defined as having three or more of the following:

• Waist circumference: >94 cm for males; >80 cm for females
• Blood Pressure: >130/85 mmHg
• HDL-Chol (mg/dl): <50 women; <40 men)
• Triglycerides (mg/dl): >150
• Glucose (mg/dl): >100 2. Subjects must meet age requirement 3. Subjects must be nonsmokers 4. Subjects must be willing to provide written consent 5. Subjects must be willing to pick-up up meals at the GCRC and return uneaten food 6. Have no food allergies 7. Subjects must not be currently following any particular diet, and must not have intentionally lost weight by dieting during the previous 3 months 8. Subjects must not be taking nutritional supplements other than a daily multivitamin 9. Subjects must be willing to maintain current physical activity routine, which cannot exceed the equivalent of > 30 minutes per day of moderate-intensity activity 10. Blood hematocrit must be at least 40 for men and 36 for women.

Exclusion Criteria:

1. Does not meet the criteria for the metabolic syndrome 2. Does not meet age requirement 3. Smoker 4. Pregnancy 5. Food allergies 6. Unwillingness to provide written consent 7. Personal history of cardiovascular disease, including prior myocardial infarction, angioplasty, or bypass surgery 8. Known cardiovascular or metabolic diseases (e.g., diabetes) 9. Currently using medications to control blood pressure, lipids, or glucose 10. Currently on a diet or has attempted weight loss by dieting during the past 3 months 11. Currently taking nutritional supplements other than a daily multivitamin 12. Currently exercising more than the equivalent of 30 minutes/day of moderate-intensity physical activity 13. Currently on oral contraceptives 14. Hematocrit below 40 for men or below 36 for women 15. Baseline systolic blood pressure below 100 mmHg

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Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Single

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
insulin sensitivity	before and after one month on each diet

Secondary Outcome Measures

Outcome Measure	Time Frame
Total and LDL-cholesterol	before and after one month on each diet
C-reactive protein	before and after one month on each diet
Homocysteine	before and after one month on each diet
Fibrinogen	before and after one month on each diet
Cytokines IL-1, IL-2, IL-6 and TNF-alpha	before and after one month on each diet
Leukocyte adhesion molecules	before and after one month on each diet
Flow-mediated dilation	before and after one month on each diet

Collaborators and Investigators

• Sponsor: University of Virginia
• Investigators: Principal Investigator: Glenn A Gaesser, PhD, University of Virginia

Study record dates

Study Major Dates

• Study Start: November 1, 2004
• Primary Completion (Actual): February 1, 2008
• Study Completion (Anticipated): August 1, 2009

Study Registration Dates

• First Submitted: December 21, 2005
• First Submitted That Met QC Criteria: December 21, 2005
• First Posted (Estimate): December 23, 2005

Study Record Updates

• Last Update Posted (Estimate): February 18, 2009
• Last Update Submitted That Met QC Criteria: February 16, 2009
• Last Verified: February 1, 2009

More Information

Terms related to this study

• Keywords: Cardiovascular disease; Diabetes; Insulin; Diet; Dietary fiber; Low-carbohydrate
• Additional Relevant MeSH Terms: Pathologic Processes; Glucose Metabolism Disorders; Metabolic Diseases; Disease; Insulin Resistance; Hyperinsulinism; Syndrome; Metabolic Syndrome
• Other Study ID Numbers: HIC11487