Weight Loss Diet Study: Low Carb vs Low Fat

NCT01661426 | Completed

• 1 other identifier: SU-07262012-10669
• Study Type: interventional
• Target: 61
• Locations: 1 country
• Sites: 1

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. \--------------------------------------------------------------------------------

Conditions

Obesity; Insulin Resistance

Keywords

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

Outcome Measures

Primary Outcomes (1)

• Change in weight

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

  Baseline and 12 months

Secondary Outcomes (12)

• Change in Fasting Insulin

  Baseline and 12 months

• Change in insulin AUC

  Baseline and 12 months

• Change in Fasting Glucose

  Baseline and 12 months

• Change in LDL-Cholesterol

  Baseline and 12 months

• Change in HDL-Cholesterol

  Baseline and 12 months

Study Arms (2)

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

ACTIVE COMPARATOR

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

Behavioral: Low-Carbohydrate Diet; Behavioral: Low-Fat Diet

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

ACTIVE COMPARATOR

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

Behavioral: Low-Carbohydrate Diet; Behavioral: Low-Fat Diet

Interventions

Low-Carbohydrate Diet BEHAVIORAL

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.

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

Low-Fat Diet BEHAVIORAL

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.

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

Eligibility Criteria

• Age: 18 Years - 50 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• 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
• Ability and willingness to give written informed consent
• No known active psychiatric illness

You may not qualify if:

• 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)

Sponsors & Collaborators

• Stanford University: lead
• Hass Avocado Board: collaborator

Study Sites (1)

Stanford University School of Medicine

Stanford, California, 94305, United States

Location

Related Publications (1)

• 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.

  PMID: 26638192 BACKGROUND

Related Links

• Study description and summary of results

MeSH Terms

Conditions

Obesity; Insulin Resistance; Weight Loss

Interventions

Diet, Carbohydrate-Restricted; Diet, Fat-Restricted

Condition Hierarchy (Ancestors)

Overweight; Overnutrition; Nutrition Disorders; Nutritional and Metabolic Diseases; Body Weight; Signs and Symptoms; Pathological Conditions, Signs and Symptoms; Hyperinsulinism; Glucose Metabolism Disorders; Metabolic Diseases; Body Weight Changes

Intervention Hierarchy (Ancestors)

Diet Therapy; Nutrition Therapy; Therapeutics; Diet; Nutritional Physiological Phenomena; Diet, Food, and Nutrition; Physiological Phenomena

Study Officials

• Christopher D Gardner, PhD

  Stanford University

  PRINCIPAL INVESTIGATOR

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: QUADRUPLE
• Who Masked: PARTICIPANT, CARE PROVIDER, INVESTIGATOR, OUTCOMES ASSESSOR
• Purpose: PREVENTION
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Associate Professor of Medicine

Model Details: 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.

Study Record Dates

• First Submitted: August 7, 2012
• First Posted: August 9, 2012
• Study Start: April 1, 2012
• Primary Completion: March 1, 2013
• Study Completion: March 1, 2013
• Last Updated: February 22, 2023

Record last verified: 2023-02

Data Sharing

• IPD Sharing: Will not share

Locations

US (1)