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Weight Loss Diet Study: Low Carb vs Low Fat

Primary Purpose

Obesity, Insulin Resistance

Status

Completed

Phase

Not Applicable

Locations

United States

Study Type

Interventional

Intervention

Low-Carbohydrate Diet

Low-Fat Diet

About this trial

This is an interventional prevention trial for Obesity focused on measuring Adults, Weight loss, Diet, Insulin Resistance, Fatty acid composition

Eligibility Criteria

18 Years - 50 Years (Adult)All SexesAccepts Healthy Volunteers

Inclusion Criteria:

Age: > or = 18 years of age
Women: Pre-menopausal (self-report) and <50 years of age
Men: <50 years of age
Race/Ethnicity: All
BMI (body mass index): 28-40 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 14 months
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 consent
No known active psychiatric illness

Exclusion Criteria:

Pregnant, lactating, within 6 months post-partum, or planning to become pregnant in the next 12 months; no menstruation for the previous 12 months
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, hypertension (except for those stable on hypertensive medications) (<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, diabetes medications, and those known to affect weight/energy expenditure
Excessive alcohol intake (self-reported, >3 drinks/day)

Sites / Locations

Stanford University School of Medicine

Arms of the Study

Arm 1

Arm 2

Arm Type

Active Comparator

Arm Label

Low-Carbohydrate Diet first, then Low-Fat Diet (IR)

Low-Fat Diet first, then Low-Carbohydrate Diet (IS)

Arm Description

Participants who were more insulin resistant based on the median AUC for insulin concentrations measured from OGTT prior to randomization.

Participants who were more insulin sensitive based on the median AUC for insulin concentrations measured from OGTT prior to randomization.

Outcomes

Primary Outcome Measures

Change in weight

Weight change was calculated as the 12 month value minus the baseline value

Secondary Outcome Measures

Change in Fasting Insulin

Fasting insulin change was calculated as the 12 month value minus the baseline value

Change in insulin AUC

Insulin area under the curve (AUC) change was calculated as the 12 month value minus the baseline value.

Change in Fasting Glucose

Fasting glucose change was calculated as the 12 month value minus the baseline value.

Change in LDL-Cholesterol

LDL-cholesterol change was calculated as the 12 month value minus the baseline value.

Change in HDL-Cholesterol

HDL-cholesterol change was calculated as the 12 month value minus the baseline value.

Change in Triglycerides

Triglycerides change was calculated as the 12 month value minus the baseline value.

Change in systolic and diastolic blood pressure

Blood pressure change was calculated as the 12 month value minus the baseline value.

Plasma fatty acid composition at baseline

Comparison of the plasma fatty acid composition between insulin sensitive and resistant participants at baseline.

Correlations between insulin markers and plasma fatty acid composition at baseline.

Interaction between insulin status and diet on 6-month changes in the plasma fatty acid composition.

Comparison of plasma fatty acid composition changes in participants on low fat and low carbohydrate diets after 6 months.

Correlations between changes in insulin markers, dietary components, and plasma fatty acid composition after 6 months.

Full Information

NCT ID

NCT01661426

First Posted

August 7, 2012

Last Updated

February 18, 2023

Sponsor

Stanford University

Collaborators

Hass Avocado Board

1. Study Identification

Unique Protocol Identification Number

NCT01661426

Brief Title

Weight Loss Diet Study: Low Carb vs Low Fat

Official Title

Weight Loss Diet Study: Low Carbohydrate vs. Low Fat and Insulin Resistance Status

Study Type

Interventional

2. Study Status

Record Verification Date

February 2023

Overall Recruitment Status

Completed

Study Start Date

April 2012 (undefined)

Primary Completion Date

March 2013 (Actual)

Study Completion Date

March 2013 (Actual)

3. Sponsor/Collaborators

Responsible Party, by Official Title

Principal Investigator

Name of the Sponsor

Stanford University

Collaborators

Hass Avocado Board

4. Oversight

Studies a U.S. FDA-regulated Drug Product

Studies a U.S. FDA-regulated Device Product

Data Monitoring Committee

5. Study Description

Brief Summary

The traditional weight loss diet recommended by health professionals has been a low-fat, high-carbohydrate, calorie restricted diet. This recommendation has been challenged by a number of alternative dietary strategies, particularly low-carbohydrate diets. In several recent weight loss studies insulin resistant adults had more success with low- vs. high-carbohydrate diets, in contrast to insulin sensitive adults who had either more success or comparable success with the low-fat diets. The investigators enrolled 61 people with a wide range of insulin sensitivity/resistance. After determining their insulin resistance status, the investigators will split them in the middle and randomly assign them to one of four groups for six months: (1) Low-Carbohydrate/Insulin Resistant (LC/IR); (2) Low-Carbohydrate/Insulin Sensitive (LC/IS); (3) Low-Fat/Insulin Resistant (LF/IR); and (4) Low-Fat/Insulin Sensitive (LF/IS) (15 people/group). After 6 months the participants will switch diet for the following 6 months, i.e. those randomized to the Low-Carbohydrate diet will switch to the Low-Fat diet and vice-versa. The primary outcome of this study is to determine whether weight loss success can be increased if one follows the dietary approach appropriately matched to their insulin resistance status. Secondary outcomes include fasting insulin, glucose, lipids, and fatty acid composition. --------------------------------------------------------------------------------

Detailed Description

The investigators hope to learn whether matching the weight loss diet to one's insulin resistance status will increase weight loss the success. The relevance of these findings is highlighted by the fact that the national recommendations for weight loss are to follow a high-carbohydrate, low-fat diet. This would imply that about half the population has been given the wrong advice in regards to the most successful dietary pattern for weight loss. Plasma fatty acid composition patterns have been shown to be associated with both insulin resistance and/or carbohydrate intake. As secondary analyses, the investigators will explore: (1) differences in plasma fatty acid composition between insulin sensitive and resistant participants at baseline; (2) the correlations between insulin markers and plasma fatty acid composition at baseline; (3) the interaction between insulin status and diet on 6-month changes in the plasma fatty acid composition; (4) plasma fatty acid composition changes in participants on low fat and low carbohydrate diets after 6 months; and (5) the correlations between changes in insulin markers, dietary components, and plasma fatty acid composition after 6 months.

6. Conditions and Keywords

Primary Disease or Condition Being Studied in the Trial, or the Focus of the Study

Obesity, Insulin Resistance

Keywords

Adults, Weight loss, Diet, Insulin Resistance, Fatty acid composition

7. Study Design

Primary Purpose

Prevention

Study Phase

Not Applicable

Interventional Study Model

Crossover Assignment

Model Description

The study employed a 2 x 2 crossover design: LF vs. LC diets and more IR vs. more IS. Study participants were classified as more IR or more IS based on the median AUC for insulin concentrations measured from an oral glucose tolerance test (OGTT) prior to randomization. Participants above the median were considered more IR and those below the median were considered more IS. A random number generator was used to stratify the randomization to LF vs. LC by insulin resistance status and gender. Participants followed their assigned diet for 6 months and then switched to the opposite diet for another 6 months.

Masking

ParticipantCare ProviderInvestigatorOutcomes Assessor

Allocation

Randomized

Enrollment

61 (Actual)

8. Arms, Groups, and Interventions

Arm Title

Low-Carbohydrate Diet first, then Low-Fat Diet (IR)

Arm Type

Active Comparator

Arm Description

Participants who were more insulin resistant based on the median AUC for insulin concentrations measured from OGTT prior to randomization.

Arm Title

Low-Fat Diet first, then Low-Carbohydrate Diet (IS)

Arm Type

Active Comparator

Arm Description

Participants who were more insulin sensitive based on the median AUC for insulin concentrations measured from OGTT prior to randomization.

Intervention Type

Behavioral

Intervention Name(s)

Low-Carbohydrate Diet

Intervention Description

Counseling/instruction on how to follow a healthy low-carbohydrate diet for 6 months. One evening class/week for 8 weeks (8 total classes). Then one class every other week for 8 weeks (4 total classes). Then one class every four weeks for 8 weeks (2 total classes): 14 evening classes, total.

Intervention Type

Behavioral

Intervention Name(s)

Low-Fat Diet

Intervention Description

Counseling/instruction on how to follow a healthy low-fat diet for 6 months. One evening class/week for 8 weeks (8 total classes). Then one class every other week for 8 weeks (4 total classes). Then one class every four weeks for 8 weeks (2 total classes): 14 evening classes, total.

Primary Outcome Measure Information:

Title

Change in weight

Description

Weight change was calculated as the 12 month value minus the baseline value

Time Frame

Baseline and 12 months

Secondary Outcome Measure Information:

Title

Change in Fasting Insulin

Description

Fasting insulin change was calculated as the 12 month value minus the baseline value

Time Frame

Baseline and 12 months

Title

Change in insulin AUC

Description

Insulin area under the curve (AUC) change was calculated as the 12 month value minus the baseline value.

Time Frame

Baseline and 12 months

Title

Change in Fasting Glucose

Description

Fasting glucose change was calculated as the 12 month value minus the baseline value.

Time Frame

Baseline and 12 months

Title

Change in LDL-Cholesterol

Description

LDL-cholesterol change was calculated as the 12 month value minus the baseline value.

Time Frame

Baseline and 12 months

Title

Change in HDL-Cholesterol

Description

HDL-cholesterol change was calculated as the 12 month value minus the baseline value.

Time Frame

Baseline and 12 months

Title

Change in Triglycerides

Description

Triglycerides change was calculated as the 12 month value minus the baseline value.

Time Frame

Baseline and 12 months

Title

Change in systolic and diastolic blood pressure

Description

Blood pressure change was calculated as the 12 month value minus the baseline value.

Time Frame

Baseline and 12 months

Title

Plasma fatty acid composition at baseline

Description

Comparison of the plasma fatty acid composition between insulin sensitive and resistant participants at baseline.

Time Frame

Baseline

Title

Correlations between insulin markers and plasma fatty acid composition at baseline.

Time Frame

Baseline

Title

Interaction between insulin status and diet on 6-month changes in the plasma fatty acid composition.

Time Frame

6 months

Title

Comparison of plasma fatty acid composition changes in participants on low fat and low carbohydrate diets after 6 months.

Time Frame

Baseline and 6 months

Title

Correlations between changes in insulin markers, dietary components, and plasma fatty acid composition after 6 months.

Time Frame

6 months

10. Eligibility

Sex

All

Minimum Age & Unit of Time

18 Years

Maximum Age & Unit of Time

50 Years

Accepts Healthy Volunteers

Eligibility Criteria

Inclusion Criteria: Age: > or = 18 years of age Women: Pre-menopausal (self-report) and <50 years of age Men: <50 years of age Race/Ethnicity: All BMI (body mass index): 28-40 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 14 months 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 consent No known active psychiatric illness Exclusion Criteria: Pregnant, lactating, within 6 months post-partum, or planning to become pregnant in the next 12 months; no menstruation for the previous 12 months 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, hypertension (except for those stable on hypertensive medications) (<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, diabetes medications, and those known to affect weight/energy expenditure Excessive alcohol intake (self-reported, >3 drinks/day)

Overall Study Officials:

First Name & Middle Initial & Last Name & Degree

Christopher D Gardner, PhD

Organizational Affiliation

Stanford University

Official's Role

Principal Investigator

Facility Information:

Facility Name

Stanford University School of Medicine

City

Stanford

State/Province

California

ZIP/Postal Code

94305

Country

United States

12. IPD Sharing Statement

Plan to Share IPD

Citations:

PubMed Identifier

26638192

Citation

Gardner CD, Offringa LC, Hartle JC, Kapphahn K, Cherin R. Weight loss on low-fat vs. low-carbohydrate diets by insulin resistance status among overweight adults and adults with obesity: A randomized pilot trial. Obesity (Silver Spring). 2016 Jan;24(1):79-86. doi: 10.1002/oby.21331. Epub 2015 Dec 6.

Results Reference

background

Links:

URL

https://med.stanford.edu/nutrition/research/completed-studies/different-diets-and-insulin-resistance.html

Description

Study description and summary of results

Learn more about this trial

Weight Loss Diet Study: Low Carb vs Low Fat

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