NC: Behavior Change Strategies (2007-2008)

Citation:
Wing RR, Jeffery RW, Burton LR, Thorson C, Nissinoff KS, Baxter JE. Food provision vs. structured meal plans in the behavioral treatment of obesity. Int J Obes Relat Metab Disord. 1996 Jan; 20 (1): 56-62.
 
Study Design:
Randomized Controlled Trial
Class:
A - Click here for explanation of classification scheme.
Quality Rating:
Positive POSITIVE: See Quality Criteria Checklist below.
Research Purpose:

The purpose of this study was to examine the contribution of the following three components, to the benefits observed with a food provision program:

  1. Meal plans
  2. Food itself
  3. Fact that the food was provided free.

On the outcome weight loss:

To evaluate whether food provision reduces the perceived barriers to weight loss, affects the types of foods available in the home, increases attendance at treatment meetings, or influences meal patterns or the types of foods consumed.

Inclusion Criteria:
  1. Aged 15 to 55 years
  2. 30 to 70 pounds overweight based on Metropolitan Life Insurance norms
  3. Not pregnant or planning to become pregnant within the next 18 months
  4. Free of illnesses that would preclude participation in a diet or exercise program.
Exclusion Criteria:

Subjects not meeting above inclusion criteria.

Description of Study Protocol:

Recruitment

  • Newspaper advertisements were used to recruit a sample of 163 overweight women
  • Half of these women were from Minneapolis-St.Paul, Minnesota area and half from Pittsburgh, Pennsylvania.  

Design

Subjects were randomly assigned to one of four treatment groups:

  1. Standard Behavioral Treatment (SBT)
  2. SBT plus structured meal plans and grocery lists (MENU Group)
  3. SBT plus structured meal plans plus food provision with participants sharing the cost of the food (BUY FOOD Group)
  4. SBT plus structured meal plans plus food provision with the food provided free (FREE FOOD Group).

Dependent Variables

Body weight and variables related to eating behavior were assessed at the start and end of the 26-week SBT program and measures of adherence (attendance and diary completions) were assessed each week throughout the program.

Intervention

The four groups participated in identical behavioral treatment (SBT) programs. Group sessions were held weekly for 26 weeks with approximately 20 members per group. Treatment sessions were led by therapists with training in nutrition or behavioral modification. All participants were assigned a calorie goal of 1,000 or 1,500kcals per day based on initial body weight and were instructed to consume less than 20% calories from fat. Exercise in the form of walking was prescribed with gradually increasing goals.

The main difference between treatment groups was in the manner the diet was prescribed:

  • Group One (SBT): Instructed to stay below their calorie and fat goals and were taught basic principles of healthy eating
  • Group Two (MENU): Provided with written meal plans indicating exactly what they should consume (including types of foods and portion sizes) for five breakfasts and five dinners each week. Also provided with a weekly grocery list to purchase foods on their meal plan. Subjects were allowed to choose their own lunches and meals on two other days of the week provided they stay within calorie and fat goals.
  • Group Three (BUY FOOD): Provided with the same meal plans as group two as well as a box of food containing all of the items described on the meal plans in the appropriate portion sizes. Subjects were required to pay $25.00 per week to receive the food.
  • Group Four (FREE FOOD): Provided with the same meal plans, the same box of food as group three, but their food was provided to them at no cost.

Statistical Analysis

Analysis completed using SAS. For analysis of variables measured at baseline and at six months, the difference between these two time points was calculated. Analysis of co-variance was then used to examine the effects of treatment conditions, center and their interactions on the changes from baseline to six months, adjusted for baseline variables.

Data Collection Summary:

Timing of Measurements
Measures were taken at baseline, the end of the 26-week Program and at one-year follow-up.

Dependent Variables

  • Variable One, weight: Measured using a balance beam scale. Participants were weighed in street clothes, without shoes. Height was assessed with a stadiometer and used to calculate BMI (kg/m2).
  • Variable Two, barriers to adherence: Subjects completed a 10-item questionnaire regarding self-perceived barriers to their weight loss efforts. For each item, participants indicated on a 5-point scale the extent to which this acted as a barrier to their weight loss effort.
    • Variable 2a: Difficulty having appropriate foods available
    • Variable 2b: Difficulty estimating portion size
    • Variable 2c: Difficulty finding time to plan meals
    • Variable 2d: Difficulty controlling eating when not hungry
  • Variable Three, eating patterns: Subjects indicated on how many days per week they usually ate breakfast, lunch, dinner and snacks and the frequency with which they ate in restaurants.
    • Variable 3a: Ate Breakfast
    • Variable 3b: Ate Lunch
    • Variable 3c: Ate Dinner
    • Variable 3d: Ate Snacks
  • Variable Four: food stored in home: Subjects were given this questionnaire to complete at home. They were asked to examine their refrigerator and cupboards to indicate which of 77 foods listed on the questionnaire were currently available in the home. After the questionnaire was pilot tested, the reliability of results across a one-week time interval and between the subject and person living in the home were adequate.
    • Variable 4a: Fruits and vegetables
    • Variable 4b: Low fat meat
    • Variable 4c: Medium fat meat
    • Variable 4d: High fat meat
    • Variable 4e: Bread and cereal
    • Variable 4f: Salty snacks
    • Variable 4g: Sweet snacks
    • Variable 4h: Low calorie alternatives
    • Variable 4i: Low calorie frozen entrées
    • Variable 4j: Regular frozen entrées

Independent Variables 

  • Variable One: Written Meal Plans
  • Variable Two: Purchased Foods
  • Variable Three: Foods provided free of charge.

Control Variables

Standard Behavioral Therapy.

Description of Actual Data Sample:
  • Initial N: 163 Female subjects (N=40 SBT, N=41 MENU, N=41 BUY FOOD, N=41 FREE FOOD)
  • Attrition (final N): 148 subjects (9%)
  • Ethnicity: N/A
  • Other Relevant Demographics: Similar across all treatment groups.

Age

  • SBT 40.5±8.2; MENU 41.7±7.7; BUY FOOD 40.8±6.7;  FREE FOOD 41.9±7.1
  • Some College or Beyond: SBT 65%; MENU 59%; BUY FOOD 56%; FREE FOOD 46%
  • Currently Married: SBT 55%; MENU 61%; BUY FOOD 59%; FREE FOOD 61%
  • Currently employed: SBT 88%; MENU 83% BUY FOOD 80%; FREE FOOD 85%.

Anthropometrics

Similar across all treatment groups

  • Weight: SBT 86.4±6.2; MENU 87.4±6.4; BUY FOOD 87.5±6.0; FREE FOOD 84.5±5.6
  • BMI: SBT 32.1±2.5; MENU 32.8±2.2: BUY FOOD 32.0±2.5; FREE FOOD 32.1±2.1.

Location

Minneapolis-St-Paul, Minnesota or Pittsburgh, Pennsylvania.

 

Summary of Results:

 Weight Loss (kg; FOOD FREE)

Variables

SBT

MENU

 BUY FOOD

FREE FOOD

Statistical Significance of Group Difference

Weight Loss at Six Months

8.0±6.2

12.0±7.2

11.7±5.4

11.4±6.5

P<0.03

Weight Loss From Baseline to one year *

3.3

6.9

 7.5

6.6

P<0.15

 *One year follow-up data were obtained for 146 subjects. One subject who had become pregnant and one who had major surgery were excluded form analysis.

Changes in Perceived Barriers to Weight Loss Efforts from Baseline to Six Months: 

Variables

SBT

MENU BUY FOOD

 FREE FOOD

P-values for contrasts 

1 vs. 2-4

P-values for contrasts

2 vs. 3-4

2a: Difficulty having appropriate foods available

 -0.01

 -0.21  -0.64

 -0.65

0.007 0.02
2b: Difficulty estimating portion size -0.39 0.66 -1.02 -0.99 0.004 0.06
2c: Difficulty finding time to plan meals

 -0.25

 -1.06  -1.12

 -1.17

0.0003 NS
2d: Difficulty controlling eating when not hungry  -0.34  -1.32  -1.02  -0.82 0.002 0.09

  • There was no statistical difference between groups three and four in the above perceived barriers to weight loss.

Change in Eating Patterns from Baseline to Six Months

 Variables SBT               MENU           BUY      FOOD  FREE FOOD         

P-Values for Contrasts 1 vs. 2-4

3a: Ate Breakfast         0.95  1.51  1.46  1.71  0.004
3b: Ate Lunch  -0.08  0.62  0.59  0.48  0.0006
3c: Ate Dinner  0.09  0.27  0.22  0.11  NS
3d: Ate snacks  0.50  -1.85  -1.89  -1.99  0.009

  • There was no statistical difference between groups two vs. three and four or groups three and four in change in eating patterns from baseline to six months.

Change in Foods Stored in Home

Variables: Food Group          SBT               MENU         BUY         FOOD FREE   FOOD        

P Values for    Contrast 1 vs. 2-4

P Values for Contrast 2 vs. 3 and 4

P Values for Contrast 3 vs. 4

Fruit and Vegetables  0.11  0.94  1.74  1.24  0.0008  NS  NS
Low Fat Meat  0.03  0.40  0.57  0.30  0.0001  0.06  0.08
Medium Fat Meats  -0.77  0.10  0.34  0.50  0.0001  NS  0.04
High Fat Meats  -0.89  -0.73  -0.97  -0.15  NS  0.02  NS
Bread and Cereal  0.00  0.81  0.82  0.95 0.0001   NS  NS
Salty Snacks  -0.24  -0.20  0.04  -0.20  NS  NS  NS
Sweet Snacks  -0.60  -0.57  -0.24  -0.71  NS  NS  NS
Low calorie alternatives  1.26  1.92  1.40  1.29  NS  NS  0.02
Low calorie frozen entrées  0.31  0.43  0.59  0.50  0.003  NS  0.09
Regular frozen entrées  -0.10  -0.11  -0.04  -0.06  NS  NS  NS

 Other Findings

  • Group attendance: Subjects in the Buy Food and Free Food Conditions (groups three and four, respectively) attended 86.2% and 83.1% of the treatment meetings, compared to only 68.4% in the MENU condition and 60.8% in the SBT condition (P<0.0001)
  • Number of meals consumed as prescribed: The groups that were given the food reported consuming more of the meals exactly as prescribed. Subjects in Groups two - four reported consuming 2.6, 2.9 and 3.4 of the five breakfast as prescribed, respectively (P<0.02) and 1.7, 2.1 and 2.7 of the five dinners (P<0.002). For both meals the contrast between the menu group and the two food provision groups was significant for the dinner meals and showed a trend for breakfast (<0.09).
  • Dietary intake: Subjects in the SBT group reported consuming 1,055kcals per day compared with a mean for the other three groups of 990kcals per day (P<0.02).
Author Conclusion:

In conclusion, a six-month behavioral treatment program which provided subjects with specific meal plans and grocery lists significantly improved weight loss compared to a standard behavioral treatment program. Actually providing food to subjects produced no additional benefits.

Funding Source:
Reviewer Comments:

This study has received a positive quality rating based on the strength of the study design and its relevance to clinical practice. One limitation of this study is that author's method of randomization was not described and so it is unclear whether study groups were comparable.

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? Yes
3. Were study groups comparable? ???
  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? No
  5.1. In intervention study, were subjects, clinicians/practitioners, and investigators blinded to treatment group, as appropriate? No
  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.) ???
  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? 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? ???
  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)? No
  8.5. Were adequate adjustments made for effects of confounding factors that might have affected the outcomes (e.g., multivariate analyses)? Yes
  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? N/A
  9.1. Is there a discussion of findings? Yes
  9.2. Are biases and study limitations identified and discussed? No
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