MNT: Disorders of Lipid Metabolism (2015)

Nasser R, Cook SL, Dorsch KD, Haennel RG. Comparison of two nutrition education approaches to reduce dietary fat intake and serum lipids reveals registered dietitians are effective at disseminating information regardless of the educational approach. J Am Diet Assoc. 2006 Jun; 106 (6): 850-859. PubMed ID: 16720126
Study Design:
Randomized Controlled Trial
A - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:
  • To evaluate the efficacy of a tailored nutrition education approach using the Stages of Change Model to reduce dietary fat intake and improve serum lipid profiles in outpatients with hyperlipidemia
  • The hypothesis is that the stages of change approach would be more effective than usual care in reducing overall dietary fat intake (specifically saturated fat) and decreasing total cholesterol, LDL-cholesterol and triglycerides.
Inclusion Criteria:
Individuals were included only if they met all of the following criteria:
  • Met the lipid clinic's admission criteria (based on guidelines established by the Saskatchwean Health Services Utilization and Research Commission for Cholesterol Testing and Treatment)
  • Passed a telephone pre-screening
  • Passed a first visit screening
    • Not on any lipid-reducing medication
    • If on beta blockers, thiazide diuretics, thyroid medications and estrogen or progesterone replacement therapy (in women), the dosage must have been maintained throughout the study.
  • Provided written informed consent.
Exclusion Criteria:
  • Did not meet the lipid clinic's admission criteria (based on the guidelines established by the Saskatchewan Health Services Utilization and Research Commission for Cholesterol Testing and Treatment)
  • If on lipid-reduction medications
  • For those on beta blockers, thiazide diuretics, thyroid medications and estrogen or progesterone replacement therapy (in women), if either the medication or dosage was altered or a new mediction was started, the participant was removed from the study.
Description of Study Protocol:


  • Men and women with hyperlipidemia were recruited through the lipid clinic of a major city hospital
  • An invitation was mailed to individuals who met the clinic's admission criteria
  • Initial eligibility was determined via telephone pre-screen and screening was completed during initial clinic visit.


40-week prospective, randomized controlled study

  • Before the initial clinic visit, participants completed a dietary behavior readiness questionnaire by telephone
  • Participants were stratified and paired using their baseline LDL-cholesterol [159mg per dL or greater and less than 159mg per dL (4.1mmol per L or greater or less than 4.1mmol per L)] and their readiness to change responses
  • After the pairing was completed the members of each pair were assigned at random to the Stages of Change Group or Usual Care Group
  • All participants were interviewed at study entry (baseline) before participating in four educational sessions over a four-week period
  • Once the classes were completed, participants had in-clinic one-on-one follow-up (40 to 45 minutes in length) at Weeks 16, 28 and 40 after program entry
  • At each of the in-clinic visits, dietary records were reviewed and suggestions for improvement or change were provided for both groups
  • For the stages of change education approach, the RD provided each participant with stage-specific activities, based on their readiness to change
  • The participants also received telephone follow-up at Weeks 10, 22 and 34 (10 to 15 minutes in length)
  • For both groups, the telephone follow-up was used to determine participants' readiness to change as well as to address any nutrition concerns expressed by the study participant
  • For the Stages of Change Group, participants were coached to find solutions for dietary change, whereas the usual care particpant was given advice without questions about their barriers to change
  • Readiness to change was evaluated at baseline and Week 40
  • Classes and clinic visits were conducted on an outpatient basis at the lipid clinic.

Blinding Used

None described.

For all participants

  • Four 90-minute nutrition classes held monthly (on separate day from the other group)
  • Participants were asked to attend all classes and could bring a friend or family member: Minimum of three of four classes was defined as mandatory to participate in the study
  • The same RD delivered nutrition information to both groups
  • The approach used with each group differed but the classes for both groups focused on five dietary behaviors associated with fat intake
    1. Added fat
    2. Cooking methods
    3. Reading labels
    4. Snacking
    5. Eating out (restaurants, cafeterias or takeout).
  • Classes emphasized quality and quantity of fat, low-fat food choices, portion control, increasing intake of fruits and vegetables, increasing soluble fiber intake and a physically active lifestyle
  • An individual's readiness to change was assessed using two different questionnaires
    • The first questionnaire was used for both groups in-clinic and telephone follow-up to monitor participants progress
    • The second questionnaire was used in order to provide stage-mathced interventions to participants in the stages of change group during class and in-clinic follow-up visits.

Two groups

  1. Stages of Change Theoretical Framework Group
    • Tailored activities developed for those in the four different stages: Contemplation, preparation, action, maintenance
    • Each individual's readiness to change was measured at the beginning of each class for the specific dietary behavior being addressed during that session
    • The first 30 minutes of class focused on basic nutrition information on the five dietary behaviors
    • The remaining 60 minutes consisted of smaller group exercises and stage-based activities
      • Participant-centered, whereby participants sought solutions to their daily activities, choices and emotions or thoughts that contribute to food choices
      • Those in pre-action stages (contemplation and preparation): Activities involved consciousness-raising, self evaluation and social re-evaluation
      • Those in action stages (action/maintenance): Activities were designed to enhance problem-solving, self-liberation and social support.
  2. Usual care dietary education approach
    • The National Cholesterol Education Program Adult Treatment Panel II Step I guidelines were used as the dietary recommendation for hyperlipidemia (reduce total fat intake to less than 30% of energy and saturated fat intake to less than 10% of energy)
    • Activities and dietary information relevant to this group were developed for those individuals ready to take action and were provided to all participants
    • This group used a teacher-centered approach whereby the RD provided the information and expertise and facilitated solutions for dietary and lifestyle choices
    • This group also completed the readiness to change questionnaire, but the information was used solely for comparisons to the Stages of Change Group.

Statistical Analysis

  • SPSS version 11.5 for Windows was used
  • Descriptive statistics (mean ± standard deviation) were used to document serum lipids, anthropometrics and dietary data
  • To confirm adequacy of the sample size, an estimation of sample size for an analysis of variance with two groups was calculated using a power of 0.90 and a medium population effect size of 0.4 with a set at 0.05
  • A sample size of 64 per group was required
  • Multiple repeated-measures analyses of variance were used to detect differences across time and between groups
  • Post-hoc comparisons were performed using the Bonferroni adjustment for multiple comparisons
  • X2 analysis was used to examine differences in demographic variables such as sex and age
  • Statistical significance was set at P<0.05 (two-tailed)
  • Intention-to-treat analysis was used by including participants lost to follow-up by carrying forward the last recorded value for serum lipid levels, anthropometrics and dietary data.
Data Collection Summary:

Timing of Measurements

  • Within the 34-month time-frame, participants completed the 40-week study in staggered groups
  • All measurements were collected at baseline, Weeks Four, 16, 28 and 40 except for blood pressure (blood pressure was measured at baseline, Weeks 16, 28 and 40).

Dependent Variables

  • Blood profiles
    • Blood samples were taken after an overnight fast of at least 10 hours and centrifuged either at the collection center or central lab within two hours of collection and tested within 24 hours
    • Plasma cholesterol and triglyceride levels were measured by enzymatic colorimetric methods
    • HDL-cholesterol was separated from LDL and very-low density lipoprotein cholesterol by precipitation and then measured by enzymatic colorimetric methods
    • LDL-cholesterol was calculated using the Friedwald equation in samples were triglycerides were less than 400mg per dL (4.5mmol per L).
  • Physiological measures: All measurements were taken twice, if the values differed, a third measure was taken and the mean of the closest two was used
    • Weight was measured (to the nearest 0.5kg) using a portable scale
    • Waist girth was measured using a non-stretchable tape
    • Heigth was measured (to the nearest 0.5cm) using a right-angle headboard and a non-stretchable tape fixed to a vertical surface
    • Blood pressure was measured using a manual mercury sphygmomanometer after five minutes of quiet rest in a sitting position.
  • Dietary analysis
    • Participants completed four-day food diaries (three weekdays and one weekend day)
    • The RD reviewed the food diaries with the participants to ensure all pertinent information was included (e.g., portion size, cooking methods)
    • A research assistant entered all diaries for nutrient composition into the FoodSmart Millenium Version 3.5.
  • Leisure-time physical activity
    • Assessed using seven-day recall questionnaire that categorized activity into vigorous (e.g., jogging), moderate (e.g., fast walking) or light intensities (e.g., yoga)
    • During the recall, participants were asked to identify the activities they participated in, frequency of participation and the average duration of each session (minimum 15-minute time blocks).

Independent Variables

Group assignment

  1. Stages of Change Group
  2. Usual Care Group.

Control Variables

None described.

Description of Actual Data Sample:
  • Initial N: 434 people were screened; 212 were recruited
  • Attrition (final N): 141 completed the study (33% attrition)
  • Age: Range from 21 to 74 years (mean, 51±11 years)
  • Ethnicity: Not described.

Other Relevant Demographics
There were no between-group differences in age or sex (P=0.67).

Variable Stages of Change Group
N =71
Usual Care Group
Sex Female 36 32
Male 35 38
Age (years)a 20-39 8 13
40-59 43 38
Over 60 20 19
Marital Status Married 43 43
Not married 17 17
Educationb High school diploma or less 19 17
Technical, community college or vocational training or less 20 13
University degree or less 20 30
Risk Factor History Smoking history 11 7
No history of smoking 59 63
Hypertensionc 8 18
Diabetes 1 0
Family history of hyperlipidemia 36 38
Family history of premature heart disease 25 36

a: Mean age was 51±11 years in the Stages of Change Group and 51±12 years in the Usual Care Group
b: Total of 12 missing cases from the Stages of Change Group and 10 missing cases from the Usual Care Group
c: Hypertension defined as individuals on hypertensive medication.


Baseline Variable Stages of Change Group
Usual Care Group
Weight (kg) 85±17 86±20
BMI (kg/m2) 30±5 30±7
Waist Girth (cm) 94±14 96±16
Women Only 88±12 89±15
Men only 101±12 104±13


Saskatchewan, Canada.

Summary of Results:

Key Findings


Baseline Week 40

Stages of Change Group (N=71)

Usual Care Group (N=70)

Stages of Change Group (N=71)

Usual Care Group (N=70)

No. Energy from fat No. Energy from fat No. Energy from fat No. Energy from fat








0 --








2 37%








6 28%
Maintenance 24 28% 25 29% 61 28% 61 26%

Other Findings

Physiologic changes

  • Both groups demonstrated a significant decrease in body weight (P<0.001), BMI (P<0.001) and waist girth (P<0.004) at four and 16 weeks, with no differences observed between groups
  • Both groups experienced a decrease in resting systolic (P<0.001) and diastolic blood pressure (P<0.006) at 40 weeks
  • Both groups demonstrated decreases in serum total cholesterol (P<0.001), LDL-cholesterol (P<0.001), triglycerides (P<0.001) and ratio of total to HDL-cholesterol (P<0.001) over the course of the study, with no significant between group differences
  • A significant decrease in HDL-cholesterol was observed at four weeks, but HDL-cholesterol rebounded to baseline values by Week 16
  • For total cholesterol, LDL-cholesterol and triglycerides, there was a decrease at four weeks (P<0.005).
Dietary changes and physical activity
  • Energy (P<0.001) and percentage of energy from fat (P<0.001), from saturated fat (P<0.001), from monounsaturated fat (P<0.002) and from polyunsaturated fat (P<0.014) changed over time, with no differences between groups
  • The percentage of energy from fat, saturated fat, monounsaturated fat and polyunsaturated fat all decreased at four weeks (P<0.005), returning to baseline levels at 16 weeks
  • No significant changes in leisure time physical activity were reported over the course of the study for either group.
Author Conclusion:
  • Registered dietitians were effective at disseminating nutrition information regardless of the educational approach
  • Providing repeated follow-up is required to significantly decrease serum cholesterol and LDL-cholesterol levels by approximately 10%
  • Registered dietitians could incorporate class activities and methods from the stages of change approach into the usual care approach.
Funding Source:
The Danone Institute of Canada
Food Company:
Reviewer Comments:
  • No blinding was specifically mentioned, but if a research assistant was responsible for entering all the dietary data, it is possible that the research assistant was blinded to group assignments (but the paper does not specifically state that)
  • It is mentioned that the answers to the questionnaires were used to assist in the stratification of participants to either the stages of change or Usual Care Group. This might indicate bias in group assignment.
  • Although the Usual Care Group received a teacher-centered approach (which is considered usual care), it seems as if the frequency of the visits was not "usual care." Most people only see their doctor or get "usual care" once per year.
  • There was no discussion of any other unplanned or extra teachings aside from the study (e.g., did participants see their regular doctors and receive extra teaching during the course of the study).
Quality Criteria Checklist: Primary Research
Relevance Questions
  1. Would implementing the studied intervention or procedure (if found successful) result in improved outcomes for the patients/clients/population group? (Not Applicable for some epidemiological studies) Yes
  2. Did the authors study an outcome (dependent variable) or topic that the patients/clients/population group would care about? Yes
  3. Is the focus of the intervention or procedure (independent variable) or topic of study a common issue of concern to dieteticspractice? Yes
  4. Is the intervention or procedure feasible? (NA for some epidemiological studies) Yes
Validity Questions
1. Was the research question clearly stated? Yes
  1.1. Was (were) the specific intervention(s) or procedure(s) [independent variable(s)] identified? Yes
  1.2. Was (were) the outcome(s) [dependent variable(s)] clearly indicated? Yes
  1.3. Were the target population and setting specified? Yes
2. Was the selection of study subjects/patients free from bias? Yes
  2.1. Were inclusion/exclusion criteria specified (e.g., risk, point in disease progression, diagnostic or prognosis criteria), and with sufficient detail and without omitting criteria critical to the study? Yes
  2.2. Were criteria applied equally to all study groups? Yes
  2.3. Were health, demographics, and other characteristics of subjects described? Yes
  2.4. Were the subjects/patients a representative sample of the relevant population? ???
3. Were study groups comparable? Yes
  3.1. Was the method of assigning subjects/patients to groups described and unbiased? (Method of randomization identified if RCT) ???
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? Yes
  3.3. Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) Yes
  3.4. If cohort study or cross-sectional study, were groups comparable on important confounding factors and/or were preexisting differences accounted for by using appropriate adjustments in statistical analysis? N/A
  3.5. If case control study, were potential confounding factors comparable for cases and controls? (If case series or trial with subjects serving as own control, this criterion is not applicable.) N/A
  3.6. If diagnostic test, was there an independent blind comparison with an appropriate reference standard (e.g., "gold standard")? N/A
4. Was method of handling withdrawals described? Yes
  4.1. Were follow-up methods described and the same for all groups? Yes
  4.2. Was the number, characteristics of withdrawals (i.e., dropouts, lost to follow up, attrition rate) and/or response rate (cross-sectional studies) described for each group? (Follow up goal for a strong study is 80%.) Yes
  4.3. Were all enrolled subjects/patients (in the original sample) accounted for? Yes
  4.4. Were reasons for withdrawals similar across groups? Yes
  4.5. If diagnostic test, was decision to perform reference test not dependent on results of test under study? N/A
5. Was blinding used to prevent introduction of bias? ???
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? ???
  5.2. Were data collectors blinded for outcomes assessment? (If outcome is measured using an objective test, such as a lab value, this criterion is assumed to be met.) Yes
  5.3. In cohort study or cross-sectional study, were measurements of outcomes and risk factors blinded? N/A
  5.4. In case control study, was case definition explicit and case ascertainment not influenced by exposure status? N/A
  5.5. In diagnostic study, were test results blinded to patient history and other test results? N/A
6. Were intervention/therapeutic regimens/exposure factor or procedure and any comparison(s) described in detail? Were interveningfactors described? Yes
  6.1. In RCT or other intervention trial, were protocols described for all regimens studied? Yes
  6.2. In observational study, were interventions, study settings, and clinicians/provider described? Yes
  6.3. Was the intensity and duration of the intervention or exposure factor sufficient to produce a meaningful effect? Yes
  6.4. Was the amount of exposure and, if relevant, subject/patient compliance measured? Yes
  6.5. Were co-interventions (e.g., ancillary treatments, other therapies) described? No
  6.6. Were extra or unplanned treatments described? No
  6.7. Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups? Yes
  6.8. In diagnostic study, were details of test administration and replication sufficient? N/A
7. Were outcomes clearly defined and the measurements valid and reliable? Yes
  7.1. Were primary and secondary endpoints described and relevant to the question? Yes
  7.2. Were nutrition measures appropriate to question and outcomes of concern? Yes
  7.3. Was the period of follow-up long enough for important outcome(s) to occur? Yes
  7.4. Were the observations and measurements based on standard, valid, and reliable data collection instruments/tests/procedures? Yes
  7.5. Was the measurement of effect at an appropriate level of precision? Yes
  7.6. Were other factors accounted for (measured) that could affect outcomes? No
  7.7. Were the measurements conducted consistently across groups? Yes
8. Was the statistical analysis appropriate for the study design and type of outcome indicators? Yes
  8.1. Were statistical analyses adequately described and the results reported appropriately? Yes
  8.2. Were correct statistical tests used and assumptions of test not violated? Yes
  8.3. Were statistics reported with levels of significance and/or confidence intervals? Yes
  8.4. Was "intent to treat" analysis of outcomes done (and as appropriate, was there an analysis of outcomes for those maximally exposed or a dose-response analysis)? Yes
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? No
  8.6. Was clinical significance as well as statistical significance reported? Yes
  8.7. If negative findings, was a power calculation reported to address type 2 error? N/A
9. Are conclusions supported by results with biases and limitations taken into consideration? Yes
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? Yes
10. Is bias due to study's funding or sponsorship unlikely? ???
  10.1. Were sources of funding and investigators' affiliations described? Yes
  10.2. Was the study free from apparent conflict of interest? ???