Comparison of the Atkins, Ornish, Weight Watchers, and Zone Diets for Weight Loss and Heart Disease - PowerPoint PPT Presentation

Loading...

PPT – Comparison of the Atkins, Ornish, Weight Watchers, and Zone Diets for Weight Loss and Heart Disease PowerPoint presentation | free to view - id: 2d1ec-M2Y0Z



Loading


The Adobe Flash plugin is needed to view this content

Get the plugin now

View by Category
About This Presentation
Title:

Comparison of the Atkins, Ornish, Weight Watchers, and Zone Diets for Weight Loss and Heart Disease

Description:

Comparison of the Atkins, Ornish, Weight Watchers, and Zone Diets for Weight ... Atkins. Percentage participants completed. Weight loss in kg (SD) at 12 months. Diet ... – PowerPoint PPT presentation

Number of Views:905
Avg rating:3.0/5.0
Slides: 48
Provided by: melod
Category:

less

Write a Comment
User Comments (0)
Transcript and Presenter's Notes

Title: Comparison of the Atkins, Ornish, Weight Watchers, and Zone Diets for Weight Loss and Heart Disease


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, 200529343-53.

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
  • 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 (0baseline to 10perfect 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
    (P0.08) 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 (pall groups and p0.70 between diets)

26
Results Weight Loss Associated with Adherence
  • There was a strong curvilinear association
    between self-reported dietary adherence and
    weight loss (r0.60 p
  • Participants in the top tertile of adherence lost
    7 of body weight on average

27
Weight loss by diet type and weight loss by
dietary adherence
28
Results Cardiac Risk Factors
  • All diets achieved modest, but statistically
    significant improvements in several cardiac risk
    factors at 1 year
  • No diets significantly altered triglycerides,
    blood pressure, or fasting glucoses at 1 year

29
Results Cardiac Risk Factors
Statistically significant
30
Results Weight loss associated with
improvement of cardiac risk factors
  • The amount of weight loss predicted the amount of
    improvement in several cardiac risk factors
    Total/ HDL cholesterol ratio (r-0.36),
    C-reactive protein (r-0.37), and Insulin levels
    (r-0.39)

31
Cardiac risk factors as a function of weight loss
32
Results Adherence
  • Dietary adherence per 3-day diet records and self
    report decreased progressively with time
  • Approximately 25 of participants in each diet
    group sustained a mean adherence level of at
    least 6-10

33
Mean Self-reported Dietary Adherence Scores of
All 4 Diet Groups
34
Results Exercise
  • Exercise levels per self-report (minimal, mild,
    moderate, vigorous) increased from baseline
    throughout the trial (pbetween diets
  • No significant association between change in
    exercise and either weight loss or cardiac risk
    factor improvement

35
Study Conclusions
  • A variety of popular diets can reduce weight and
    cardiac risk factors under realistic conditions,
    but only for the most adherent
  • Sustained adherence to a diet rather than diet
    type was the key predictor of weight loss and
    cardiac risk factor reduction

36
Discussion Is this study relevant?
  • Q Can I apply it to my clinic population?
  • A Probably. The participants in this study are
    not medically dissimilar to patients in our
    clinics and the study is realistic. However,
    participants who called likely more motivated
    than typical patient. Study did not report SES,
    language, ethnicity, etc.

37
Discussion Is this study relevant?
  • Q Are the likely benefits worth the potential
    harms and cost?
  • A Probably. Obesity has been shown to increase
    morbidity and mortality and even modest weight
    loss has benefit. No obvious harm in the short
    term. Long term has not been studied. Also, does
    being on a diet decrease quality of life?

38
Discussion Is this study relevant?
  • Q Were all the clinically important outcomes
    considered?
  • A Possibly. Besides weight loss and cardiac
    risk factors which have been shown to decrease
    morbidity and mortality, investigators could have
    examined quality of life. Mortality was beyond
    the scope of this study.

39
Discussion Is this study valid?
  • Q Was the assignment of participants to
    intervention random?
  • A Yes, a computer generated a diet to each
    small group and at only one of 4 meeting times

40
Discussion Is this study valid?
  • Q Was follow up complete?
  • A No. This study drop out rate was large at 42
    (consistent with dropout rates in other diet
    studies). Data was analyzed with the assumption
    was that those who discontinued would be back to
    baseline and missing data was substituted with
    baseline. This is a very conservative measure.
    Results were consistent when missing data was
    excluded entirely from the analysis

41
Discussion Is this study valid?
  • Q Were patients analyzed in the groups to which
    they were randomized?
  • A Yes, this study followed the intention to
    treat principle

42
Discussion Is this study valid?
  • Q Were participants, clinicians and personnel
    blinded to the intervention?
  • A No, participants and providers knew which diet
    they were assigned by the first meeting, which
    could have affected outcomes depending on
    expectations, biases. (those optimistic about the
    diet theyve been assigned may do better) Only
    the lab personnel was blinded, the person least
    likely to affect outcome.

43
Discussion Is this study valid?
  • Q Were the groups similar at the start of the
    trial?
  • A Yes demographically, as well as by baseline
    weight, caloric intake and cardiac risk factors

44
Discussion Is this study valid?
  • Q Were the groups treated equally apart from
    their intervention?
  • A Maybe. Investigators standardized their
    recommendation for daily MVI, 60 minutes of
    exercise/ week, and avoiding commercial support.
    However they did give each participant the
    corresponding literature and cookbooks, which are
    different from one another. Also, there was no
    mention of standardized small group meeting
    content or structure

45
Discussion What are the results?
  • Q How large and precise was the treatment
    effect?
  • A Results were only modest in weight loss and
    improvement in cardiac risk factors, but
    statistically significant.

46
Discussion
  • What if you just held the meetings and followed
    weight and cardiac risk factors?
  • How accurate is the data? Diet records usually
    underestimate
  • How real is the adherence score? It may be all
    relative

47
Application
  • What advice would I give to patients who want to
    lose weight? Tell them to just pick the diet
    that you think will work for you and stick to it?
  • Would I recommend a diet based on a patients
    cardiac risk factors?
  • How can I encourage dietary adherence?
About PowerShow.com