Effects of a Ketogenic Diet on Body Weight and Cardiovascular Risk Factors

This pilot study is a randomized, controlled clinical trial to compare anthropometric and metabolic changes associated with six months of weight management by means of a very low carbohydrate diet or a calorically-restricted low fat diet. We hypothesized that the low fat diet would be associated with more weight loss and improvement of cardiovascular risk factors than the low carbohydrate diet.

Study Overview

• Status: Completed
• Conditions: Obesity
• Intervention / Treatment: Behavioral: Clinical diet trial

Detailed Description

Low carbohydrate diets, including high-fat, 'ketogenic' diets, have moved to the forefront of popular diets promoted for weight loss in the United States. These diet plans have been aggressively marketed to millions of Americans every year. However, there has been virtually no rigorous study of low carbohydrate, high fat diets either with regard to efficacy in promoting weight loss or effects on cardiovascular risk factors. Because very low carbohydrate diets (i.e., the ketogenic diets) recommend increased intake of fat, and saturated fat, we hypothesized that following one of these diet plans could actually worsen important risk factors for cardiovascular disease. This is an issue of great importance because large numbers of people experiment with low carbohydrate diets despite not knowing their effects on blood pressure, plasma lipid levels, and glucose tolerance. Therefore, we have proposed a clinical trial to test our hypothesis. In this study, we will compare the effects of three months of a ketogenic diet (as promoted by Dr. Robert Atkins) with three months of a weight loss diet that conforms to the American Heart Association dietary guidelines in a group of 100 otherwise healthy obese subjects. During the course of the study, we will determine the effects of diet on 1) body weight, percent fat, and resting metabolic rate, 2) blood pressure, 3) plasma lipids, 4) measures of glucose tolerance, and 5) measures of psychological health and eating behaviors. This pilot study will provide the preliminary data needed to demonstrate the efficacy (or lack thereof) of a popular weight loss technique (i.e., the ketogenic diet) that is currently being criticized by professional organizations. Armed with preliminary data, the investigators plan to further investigate the long-term anthropometric and metabolic effects of ketogenic diets with a larger sample.

• Study Type: Interventional
• Enrollment (Actual): 103
• Phase: Phase 1

Contacts and Locations

Study Locations

• United States
  • Ohio
    • Cincinnati, Ohio, United States, 45221-0038
      • University of Cincinnati

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 18 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: Female

Description

Inclusion Criteria:

• Obese men and women with a BMI of 30-34 kg/m2, at least 18 years of age, who have had stable body weight (i.e., no gain or loss of >5% of body weight) for the preceding six months, who have normal oral glucose tolerance, and who are able to commit to a six month study.

Exclusion Criteria:

• Pregnancy, lactation, active medical or mental illness requiring treatment, recent (within 1 year) use of appetite suppressing compounds, previous use of the ketogenic diet.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: None (Open Label)

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Body weight	6 months

Secondary Outcome Measures

Outcome Measure	Time Frame
Blood pressure	6 months
Body fat via dual energy x-ray absorptiometry (DXA)	6 months
Resting metabolic rate via indirect calorimetry	6 months
Fasting plasma total cholesterol, LDL-cholesterol, HDL-cholesterol, and triglycerides	6 months
Fasting insulin and glucose	6 months
Psychological health and eating behaviors via surveys	6 months

Collaborators and Investigators

• Sponsor: University of Cincinnati
• Collaborators: American Heart Association
• Investigators: Principal Investigator: Bonnie J Brehm, PhD, University of Cincinnati

Publications and helpful links

General Publications

• Brehm BJ, Seeley RJ, Daniels SR, D'Alessio DA. A randomized trial comparing a very low carbohydrate diet and a calorie-restricted low fat diet on body weight and cardiovascular risk factors in healthy women. J Clin Endocrinol Metab. 2003 Apr;88(4):1617-23. doi: 10.1210/jc.2002-021480.
• Brehm BJ, Spang SE, Lattin BL, Seeley RJ, Daniels SR, D'Alessio DA. The role of energy expenditure in the differential weight loss in obese women on low-fat and low-carbohydrate diets. J Clin Endocrinol Metab. 2005 Mar;90(3):1475-82. doi: 10.1210/jc.2004-1540. Epub 2004 Dec 14.
• O'Brien KD, Brehm BJ, Seeley RJ, Bean J, Wener MH, Daniels S, D'Alessio DA. Diet-induced weight loss is associated with decreases in plasma serum amyloid a and C-reactive protein independent of dietary macronutrient composition in obese subjects. J Clin Endocrinol Metab. 2005 Apr;90(4):2244-9. doi: 10.1210/jc.2004-1011. Epub 2005 Jan 25.

Study record dates

Study Major Dates

• Study Start: June 1, 2000
• Study Completion (Actual): October 1, 2002

Study Registration Dates

• First Submitted: July 6, 2007
• First Submitted That Met QC Criteria: July 6, 2007
• First Posted (Estimate): July 10, 2007

Study Record Updates

• Last Update Posted (Estimate): July 10, 2007
• Last Update Submitted That Met QC Criteria: July 6, 2007
• Last Verified: July 1, 2007

More Information

Terms related to this study

• Keywords: Obesity; Weight loss; Diet fads
• Additional Relevant MeSH Terms: Body Weight
• Other Study ID Numbers: 0060334B