HD: Effectiveness of Nutrition Intervention Methods (2010)
- To examine whether the addition of motivational interviewing (MI) to a culturally-targeted group-based behavioral weight loss program for African American (AA) women enhanced adherence to the group program
- To explore the effect of MI on diet and physical activity behaviors and weight loss outcomes
- To examine whether MI increased internal motivation for weight loss and self-efficacy for diet and exercise.
The women were recruited from a community health center serving predominantly lower-income AAs. Eligibly criteria included:
- 18 years or older
- Obese (BMI=30 to 50)
- Not pregnant or intending to become pregnant within six months
- Not currently involved in other weight loss treatments
- Free from psychiatric illness or substance abuse
- Able to walk continuously for at least 10 minutes
- Not planning to move out of the area (Kansas City, MO area) within six months
- Able to obtain medical clearance from a primary care provider.
The authors did not indicate how they defined African American, nor did they list it as an inclusion criteria; however, being African American was defined as an inclusion criteria throughout the study.
Subjects that did not meet the inclusion criteria were excluded.
African American women were recruited from a community health center serving predominantly lower-income African Americans and the surrounding community in Kansas City, Missouri. They were recruited using flyers, a staffed table in the health clinic lobby and by word of mouth.
This was a randomized controlled trial. Participants were randomized to receive four individual session of MI or health-education (HE for attention control) as an adjunct to a 16-week culturally targeted behavioral weight loss program.
After recruitment and screening, participants were randomized sequentially using a closed-envelope procedure that was created by the study statistician. The investigators and data collection staff were concealed from this information.
- All subjects received the 16 session behavioral weight loss program, which was adapted from the "Lifestyle Balance" program of the Diabetes Prevention Program (DPP). The program was administered in 90-minute weekly sessions in groups of 12 to 14 participants.
- MI and HE participants were in the same groups to ensure comparable groups across conditions
- A doctorate-level psychologist and a masters-level counselor or dietitian led each group, following a treatment manual. During the first 30 minutes, the participants weighed in, reviewed weekly self-monitoring logs, and shared strategies with the group. The next 60 minutes addressed the weekly topic, which included nutrition and physical activity education and behavioral modification skill building.
- Cultural adaptations were identified from previous work and included:
- Social support
- Addressing barriers related to transportation, neighborhood safety, literacy and other stressors
- Guidance about food and physical activity (PA) were made relevant to cultural practices
- Preferences for larger body sizes were recognized
- AA community leaders who had succeeded at weight loss were invited as peer mentors
- Participants developed group names for themselves (e.g., Jazzy Women Taking It Off and Dedicated Divas) to increase ownership
- Sessions were less didactic and more interactive in nature
- The subjects randomized to MI received four separate 30-minute individual MI sessions with an advanced doctoral clinical psychology student. The same counselor provided all four sessions. This counselor did not facilitate the group sessions with their given participants.
- The MI sessions occurred at weeks zero (in-person), three (by phone), eight (in-person) and 13 (by phone). Consistent with MI, the majority of each session was spent eliciting change talk by exploring motivation
- Baseline differences between MI and HE conditions and participants retained and those lost to follow-up were tested using two-sample T-tests and chi-square analyses
- Two-sample T-tests were used to compare MI and HE conditions on satisfaction and adherence variables
- Main effects of treatment on pre- to post-treatment outcomes were analyzed using two-way repeated measures ANOVA with treatment condition as the between-group factor. Participants were analyzed in the condition to which they were randomized.
Timing of Measurements
- Program adherence was measured weekly
- Satisfactions with the entire program plus intervention was measured post-treatment (week 16)
- Dietary intake, physical activity, weight, height, motivation, self-efficacy for diet and exercise were measured at baseline and at 16 weeks.
- Weight: Measured without shoes using a digital scale to the nearest 0.1. Weight was then adjusted (decreased) by two pounds to account for clothing.
- Height: Without shoes, rounding to the nearest 0.25 inch
- BMI: The height and weight were used to calculate the BMI
- The outcome variables of energy intake, percent calories from fat and fruit and vegetable consumption were obtained using 24-hour dietary recalls. These were conducted using the USDA multiple pass approach using three days of recalls .
- Adherence to the behavioral weight loss program: Attendance, number of self-monitoring logs turned in and level of completion of self-monitoring logs
- internal motivation: Measured using the six-item autonomous regulation scale of the Treatment Self-Regulation Questionnaire
- Self-efficacy: This measure was adapted from a tool developed by Bandure to assess confidence in the ability to overcome common barriers to regulating healthy eating and exercise. Eight items were removed from the measurement tool that were felt to be less relevant and two were added for assessing exercise self-efficacy.
- Four sessions of motivational interviewing sessions, delivered at week zero, week three, week eight and week 13
- Attention control group: Four health education sessions delivered on the same time frame as those randomized to receive the MI sessions. The participants chose four topics from six options (breast, colon or cervical cancer screening; smoking cessation; helping others quit smoking; and improving sleep).
All subjects received the 16-session behavioral weight loss program that was adapted from the "Lifestyle Balance" program of the Diabetes Prevention Program (DPP). The program was administered in 90-minute weekly sessions in groups of 12 to 14 participants. MI and HE participants were in the same groups to ensure comparable groups across conditions.
- Initial N: Total (N=44); MI (N=21); HE (N=23)
- Final N: Lost to follow-up in MI (N=6); lost to follow-up in HE (N=4)
- Age: All subjects 44.3±11.6; MI 41.6±12.3; HE 47.2±10.4
- Other relevant demographics: Education, marital status, employment status, co-morbid medical conditions, previous weight loss attempts, BMI, weight, baseline dietary intake, percent kcal from fat, total fruit and vegetable intake, baseline physical activity levels, internal motivation, dietary self-efficacy and PA self-efficacy were all analyzed and baseline data presented. No significant differences were found between the MI group and the HE group.
- Location: Kansas City, Missouri.
Means, Standard Deviations and Effect Sizes for Change in Diet, Physical Activity, Weight and Psychosocial Factors by Total Sample and Treatment Condition
|Variable||MI (N=14)||HE (N=19)||Total (N=33)||Cohen’s d BG|
Total kcals per day
|-434 (538)||-486 (801)||-465 (696)||- 0.08|
Percent of kcals from fat
|-3.4 (9.1)||-5.5 (7.7)||(8.2) -0.25||-0.25|
|Fruit and vegetable servings per day||1.2 (2.8)||2.0 (3.2)||1.7 (3.0)||-0.27|
|Kcal per week per kg||5.4 (31.1)||8.3 (20.4)||7.0 (25.1)||-0.11|
|Activity minutes||92 (435)||108 (282)||101 (350)||-0.04|
|Weight (kg)||-2.6 (4.2)||-3.2 (5.7)||-3.0 (5.1)||-0.12|
|BMI||-1.0 (1.5)||-1.1 (2.0)||-1.1 (1.8)||-0.06|
- The addition of MI to this weight loss program did not improve adherence or treatment outcomes
- Main effects for condition were not statistically significant for diet, physical activity or weight outcomes. There was change over time for both groups, with a decrease in kcals, percent of kcals from fat and an increase in fruit and vegetable consumption for both the MI and HE group.
- Those receiving MI were more satisfied, but not more likely to attend the group interventions, to change their dietary intake or physical activity or to lose weight compared to women who received a HE attention control
- Women in both conditions also both reported decreases in motivation and self-efficacy. Those who were higher in these variables at baseline had greater decreases over time, but treatment group did not matter.
This study suggests that MI may not be as effective with AA populations as Caucasians for weight loss and health behavior change. Further work is needed to replicate this finding and dismantle the SES barriers versus sociocultural factors that may limit the impact of MI.
This is a well-designed study with a clearly defined study question and secondary questions as well. The findings suggest that we have a long way to go in determining how cultural components play into behavior change programs for long-term weight loss success.
Quality Criteria Checklist: Primary Research
|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)||N/A|
|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|
|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?||Yes|
|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)||Yes|
|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?||No|
|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?||???|
|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?||Yes|
|5.1.||In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate?||Yes|
|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?||N/A|
|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?||N/A|
|6.6.||Were extra or unplanned treatments described?||N/A|
|6.7.||Was the information for 6.4, 6.5, and 6.6 assessed the same way for all groups?||N/A|
|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?||Yes|
|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)?||N/A|
|8.5.||Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)?||???|
|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?||No|
|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?||Yes|
|10.1.||Were sources of funding and investigators' affiliations described?||Yes|
|10.2.||Was the study free from apparent conflict of interest?||Yes|