Comparison of Popular Weight Loss Diets

National Institutes of Health (NIH)

Status and phase

Completed

Phase 2

Conditions

Obesity

Treatments

Behavioral: Atkins diet (extremely low carbohydrate)

Behavioral: Ornish diet (very low fat)

Behavioral: Zone diet (low carbohydrate, high protein)

Study type

Interventional

Funder types

Other

NIH

Identifiers

NCT00079573

R21AT001098-01A1

Details and patient eligibility

About

This study will compare the safety and effectiveness of three popular weight loss plans. These plans will be compared with the USDA Dietary Guidelines.

Full description

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.

Sex

Female

Ages

30 to 50 years old

Volunteers

Accepts Healthy Volunteers

Inclusion and exclusion criteria

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)