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Adult Weight Management

AWM: Meal Replacements (2006)


Mattes RD. Ready-to-eat cereal used as a meal replacement promotes weight loss in humans. Journal of the American College of Nutrition. Vol. 21, No. 6, 570-577 (2002).

PubMed ID: 12480804
Study Design:
Randomized Controlled Trial
A - Click here for explanation of classification scheme.
Quality Rating:
Neutral NEUTRAL: See Quality Criteria Checklist below.
Research Purpose:

The primary aim was to determine whether ready-to-eat cereal used as a portion-controlled meal replacement promotes weight loss. Additional aims were to determine whether weight loss differed if the cereal was provided as a single brand or a variety of brands and whether this use of ready-to-eat cereal promotes continued weight loss following transition to a high-fiber, high-volume (volumetric) diet.

Inclusion Criteria:

Eligibility criteria included:

  • 20 to 60 years of age
  • Body mass index between 25 and 35 kg/m2
  • Weight stable (no deviation greater than three kg over the prior three months)
  • Good health
  • Not initiating or terminating the use of medications reported to influence appetite or body weight during the proposed study period
  • Stable activity level
  • Low dietary disinhibition
  • Regular eating habits (i.e., three meals per day including breakfast)
  • Lactose tolerance.
Exclusion Criteria:
Those not meeting inclusion criteria were excluded from study.
Description of Study Protocol:
  • Recruitment: Recruited through public advertisement
  • Design: Randomized controlled trial
  • Intervention: Participants randomly assigned to one of four dietary treatment groups for six weeks
  • Statistical Analysis: Within-subjects analyses (repeated measures ANOVA) were conducted with time as the within-subject factor and treatment as a between-subject factor. Paired T-tests were used for post-hoc analysis, following significant F-tests. Criterion for statistical significance was P<0.05, two-tailed.
Data Collection Summary:

Timing of Measurements

  • Body composition was measured and diet records, appetite questionnaires and activity logs completed during baseline and end of Intervention Weeks Two and Six.

Dependent Variables

  • Body weight and composition determined on a clinical scale with subjects in a gown after voiding at a consistent time of day for the individual. Fat mass, lean body mass and total body water were determined by bioelectrical impedance analysis.
  • Hunger assessment: One-third of the participants (determined by random number table) completed a short questionnaire, eliciting information about hunger, desire to eat, prospective consumption and fullness at hourly intervals during waking hours, while keeping their diet records.

Independent Variables

  • Dietary intervention as below. Diet records for three days (two weekdays and one weekend day) analyzed with ESHA Food Processor. 
  • Group One consumed a serving of a single cereal brand with milk and 100 kcal fruit for breakfast and as a replacement for lunch or dinner for Weeks One and Two, followed by Volumetric diet for Weeks Three through Six, with a target energy restriction of 500 kcal/day. 
  • Group Two followed same protocol, but selected a variety of cereals during Weeks One and Two
  • Group Three received no dietary instruction during the six-week study
  • Group Four received no intervention prior to the adoption of Volumetric diet for Weeks Three through Six
  • Activity logs were completed at the same intervals by one-third of participants and the remainder of participants did not keep a log.
Description of Actual Data Sample:

Initial N

  • 133 individuals recruited
    • Group One: N=33
    • Group Two: N=37
    • Group Three: N=36
    • Group Four: N=30.

Attrition (Final N)

  • 109 individuals completed (18% dropout rate)
    • Group One: N=28 (six males, 22 females)
    • Group Two: N=28 (three males, 25 females)
    • Group Three: N=26 (seven males, 19 females)
    • Group Four: N=27 (nine males, 18 females).
  • Subjects had different reasons for withdrawal.


  • Group One: Mean age 43.0±1.9 years
  • Group Two: Mean age 40.9±2.3 years
  • Group Three: Mean age 41.6±2.4 years
  • Group Four: Mean age 38.2±2.8 years.


  • Group One: 26 Caucasian, zero African-American, one Asian, one other
  • Group Two: 25 Caucasian, zero African-American/one Asian, two other
  • Group Three: 24 Caucasian, one African-American/zero Asian, one other
  • Group Four: 23 Caucasian, two African-American/one Asian, one other.

Other Relevant Demographics

  • Group One: Mean BMI=28.9±0.4
  • Group Two: Mean BMI=29.39±0.6
  • Group Three: Mean BMI=29.3±0.6
  • Group Four: Mean BMI=29.3±0.6.


  • Groups did not differ on baseline characteristics.


  • Indiana.
Summary of Results:

Other Results

  • The cereal interventions resulted in 640±109 and 617±105 kcal/day in Groups One and Two, respectively, during the two-week cereal intervention, leading to comparable weight losses (1.91±0.19 kg for Group One and 1.37±0.15 kg for Group Two) that were significantly greater than that for Group Three (0.08±0.15 kg).
  • The cereal interventions resulted in weight loss compared to baseline (95% confidence interval: - 2.29 to -1.52 for single cereal, -1.69 to -1.06 for variety cereal). The weight change for the single cereal group was greater than that of the variety group (P=0.025). Significant changes were not reported for the control groups.
    • 88% of single cereal participants lost fat mass.
    • 81.5% of variety cereal participants lost fat mass.
    • 48% of non-diet group lost fat mass.
    • 44% of control group lost fat mass. 
  • The control group was not on a reduced calorie intake.
Author Conclusion:

This trial demonstrated that ready-to-eat cereal may be used to promote weight loss, when consumed as a portion-controlled meal replacement. Further, it extends knowledge generally on the meal replacement approach to weight management. It suggests a broad array of foods may be used in this manner, thereby facilitating individualized dietary prescriptions that will best meet personal preferences.

Second, it indicates meal replacements can vary in sensory properties without compromising compliance and weight loss.

Third, this work confirms earlier findings on the efficacy of a novel use of meal replacements as a means to transition individuals to diets that promote adoption of improved life-long dietary habits. Thus, it is an additional weight management option that may be especially suitable for individuals where portion control is problematic.

Funding Source:
Kellogg Company
Food Company:
University/Hospital: Purdue University
Reviewer Comments:
  • This study simply supported that a reduced calorie diet leads to weight loss.
  • The type of cereal does not make a difference.
  • The theory of the volumetric diet seems to play more of a role in weight loss than the use of cereals.
  • Participants reported hunger in the cereal phase of the diet.
  • The hypotheses that a variety of cereals would increase weight loss in participants was not proven.
  • It is not reasonable to conclude that the use of cereal in one's diet would lead to weight loss.
  • Using the volumetric diet with cereal and controlled portions may lead to to weight loss.
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) Yes
  3.2. Were distribution of disease status, prognostic factors, and other factors (e.g., demographics) similar across study groups at baseline? ???
  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? ???
  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? No
  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.) No
  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? ???
  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? ???
  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? Yes
  6.6. Were extra or unplanned treatments described? Yes
  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? ???
  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)? 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? 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? ???