Comparison of the Atkins, Ornish, Weight Watchers, and Zone Diets for Weight Loss and Heart Disease Risk Reduction: A Ra

1. Comparison of the Atkins, Ornish, Weight Watchers, and Zone Diets for Weight Loss and Heart Disease Risk Reduction: A Randomized Trial Melody Lee, MD UCSF Family and Community Medicine Journal Club January 21, 2005

2. Introduction: Context Obesity has become an epidemic

3. Introduction: Context Popular diets have become increasingly prevalent and controversial Patients and clinicians are interested in using popular diets for disease prevention However, there is little data regarding the relative benefits, risks, effectiveness and sustainability of popular diets

4. Comparison of the Atkins, Ornish, Weight Watchers, and Zone Diets for Weight Loss and Heart Disease Risk Reduction: A Randomized Trial Michael L. Dansinger; Joi Augustin Gleason; John L. Griffith; Harry P. Selker; Ernst J. Schaefer JAMA. Jan 5, 2005;293:43-53.

5. Goals Assess the effectiveness of four popular diets for weight loss and cardiac risk factors, and to assess self-reported adherence rates to each diet

6. Study description Single-center one-year randomized trial at an academic center in Boston, Mass Enrolled July 2000- January 2002

7. Methods: Inclusion Criteria Adults with BMI between 27 and 42 At least one of the following metabolic risk factors: Fasting glucose > 110mg/dL Total cholesterol > 200 mg/dL LDL cholesterol > 130 mg/dL HDL cholesterol< 40 mg/dL Triglycerides > 150 mg/dL SBP >145 or DBP > 90 Or current use of oral medications to treat HTN, DM, or dyslipidemia

8. Methods: Exclusion Criteria Unstable chronic illness Insulin therapy Urinary microalbumin > 2 times normal Serum creatinine > 1.4mg/dL Clinically significant LFT or TFT abnormalities Weight loss medication Pregnancy

9. Methods: Participants Recruited in Greater Boston area via newspaper advertisements, television publicity 1010 screened via telephone (513 not interested or too busy) 247 screened in person (22 no risk factors, 14 too busy, 13 diets too extreme) 160 final participants 40 participants randomized to each diet group

10. Methods: Randomization Participants chose 1 of 4 class times Once approximately 10 participants per class time, 1 of 4 diets were assigned to the small group by according to computer-generated randomized Latin square sequence Each diet was assigned to each class time only once per cycle x 4 cycles

11. Methods: Blinding Study personnel blinded to dietary assignment until after small group roster finalized to avoid recruiting bias Diet assignment was revealed to small group at first meeting and participants were given diet specific rationale, written materials, and official diet cookbook Lab personnel were blinded

12. Methods: Intervention One of four popular diets: Atkins, Zone, Weight Watchers, or Ornish Only dietary components, not other aspects that may be unique to dietary program

13. Methods: Dietary Intervention Less than 20 g of carbohydrate daily with a gradual increase to 50 g daily 40-30-30 balance of percentage calories from carbohydrate, fat, and protein respectively

14. Methods: Dietary Intervention Keep total daily �points� in a range determined by current weight. Each point 50 calories. Participants roughly aimed for 24-32 points daily. Point values for certain food provided through diet Vegetarian diet containing 10% calories from fat

15. Methods: Standard Intervention Standard recommendation: daily MVI, 60 minutes of exercise weekly, avoid commercial support services A dietician and physician met with each small group for 1 hour on 4 occasions during the first 2 months of study Subsequent meetings aimed to maximize adherence by reinforcing positive changes and addressing barriers to adherence After 2 months, participants were encouraged to follow their assigned diet according to their interest

16. Methods: Outcomes Participants were blinded to timing of assessments until 2 weeks prior Three main outcomes were studied: Weight loss Cardiac risk factors Adherence

17. Methods: Determining Weight Loss Baseline weight taken 2 weeks prior to dietary intervention, subsequent weight assessed using same scale with light clothing and no shoes

18. Methods: Determining Cardiac Risk Factors Overnight fast: Total cholesterol HDL cholesterol Triglycerides Glucose Insulin High sensitivity C-reactive protein Creatinine Friedewald formula for LDL cholesterol 24-hour urine for total protein, nitrogen and creatinine

19. Methods: Determining Adherence Submitted 3-day food records at 1,2,6 and 12 months were entered into computer program that calculated average daily macronutreints and micronutrients and adherence was scored on a 10 point scale (0=baseline to 10=perfect adherence) Self report of adherence in past 30 days using same scoring system

20. Methods: Analysis Standard statistical analysis The assumption was made that participants who discontinued the study were unchanged from baseline Investigators examined the data twice: (1) with the missing data substituted by baseline values (2) with the missing data excluded

21. Results: Participants The 40 participants in each diet group were similar in terms of baseline characteristics At baseline there was no significant differences in caloric or macronutrients between diet groups Mean age 49, range 22-72 81/160 women

22. Results: Attrition and AEs Attrition was 21% at 2 months, 38% at 6 months and 42% at 12 months At 12 months, there was a nonsignificant trend (P=0.08) toward a lower continuation rate for more extreme diets (Atkins and Ornish) compared to moderate diets (Zone and Weight Watchers) The most common reasons for discontinuation was (1) assigned diet was too difficult or (2) not yielding enough weight loss No adverse events

23. Results: Weight Loss All 4 diets resulted in statistically significant, albeit modest, weight loss at 12 months. There was not a statistically significant difference between the diets Greater effects were observed in study completers 25% of initial participants lost 5% of initial body weight, 10 % of participants lost 10% or more

24. Results: Weight Loss

25. Results: Dietary Intake At one year, the mean daily caloric reduction from baseline was 138 for Atkins, 251 for Zone, 244 for Weight watchers and 192 for Ornish (p<0.5 all groups and p=0.70 between diets)

26. Results: Weight Loss Associated with Adherence There was a strong curvilinear association between self-reported dietary adherence and weight loss (r=0.60; p< .001) Participants in the top tertile of adherence lost 7% of body weight on average