DF: Obesity (2008)
The purpose of this study was to examine the effects of adding guar gum to a low-energy semi-solid meal on appetite and body weight loss.
Participants volunteered for the study after being recruited by advertisements in local newspapers.
No exclusion criteria was disclosed or discussed in this paper.
- Recruitment: 36 male, mainly overweight, subjects volunteered after being recruited by advertisements in local newspapers
- Design: This was a randomized control trial with crossover design throughout the experiment
- Blinding used (if applicable): Only one relatively minor case of blinding; a random subsample of 15 subjects were blinded to the type of water (tap water or deuterium) for the hydration study, used to assess accuracy of food intake. No other incidences of blinding were mentioned in the study.
Intervention (if Applicable)
- The subjects were exposed to three different diets for two-week periods, with four-week washout periods between diets. All subjects were started with a one-week baseline period.
- Random assignment, then crossover to three meal types for two weeks each
- Subjects consumed the following at breakfast, lunch and snack, which provided 947kJ (17.9g protein, 21.0g CHO, 7.9g fat):
- Semi-solid meal with (2.5g per meal) guar gum (SSM+): Modified guar gum was a highly purified dietary galacto-mannan fiber, which forms a gel in five to seven minutes
- Semi-solid meal without guar gum (SSM)
- Solid meal without guar gum (SM).
- Subjects were allowed an additional piece of fruit at lunch
- At dinner, subjects ate what they liked but were instructed to drink not more that one alcoholic beverage or soft drink Subjects were told to avoid snacks, but were allowed unlimited coffee, water and tea without sugar or milk.
Statistical Analysis
- Data are presented as means with degree of standard errors
- Analysis of variance for repeated measures
- Seffe-F post-hoc test was used
- The measurements at baseline and the end of the experiment were compared using paired T-tests
- Pearson correlation coefficients were calculated to determine the relationship between selected variables.
Dependent Variables | Timing of Measurements |
Body Weight | Beginning and end of baseline and at the end of each intervention |
Waist-Hip Circumference | At screening and end of experiment |
Total Body Water
|
Before baseline and during each intervention |
Blood Parameters
|
At baseline |
Eating Behaviors Dutch translation of "Three Factor Eating Questionnaire"
Also, Herman Polivy questionnaire for weight fluctuations |
Beginning and end of baseline and during each intervention |
Food Intake and Meal Frequency
|
Last seven days of each intervention |
Satiety (hunger, satiety, fullness, desire to eat, appetite, estimation of how much one could eat and thirst)
|
At Day Four, during baseline and Day 11, during each intervention Questionnaires completed at 10 fixed time-points: Before and after breakfast, between 10 am and 11 am, before and after lunch, before and after 4 pm snack, before and after dinner and between 10 pm and 11 pm. |
Tolerance
|
At end of each intervention |
Hedonic Value and User-Friendliness Questionnaire
|
Completed at end of experiment |
At baseline, washout periods Also consumed for dinner in interventions with limited alchohol and soft drinks (no more than one at each dinner) Self-Prepared Solid Meal (SM) Semi-Solid Meal Without Additional Fiber (SSM-) Semi-Solid Meal with Additional Fiber (SSM+)
Independent Variable
Timing of Variable
Self-Selected Diet
During intervention periods, see schedule below
During intervention periods, see schedule below
During intervention periods, see schedule below
Control Variable (Baseline Diet, Diet Interventions and Washout Periods) |
Intervention Timing SSM+, SSM-, SM (N=10) |
Baseline Diet |
One week at start of experiment |
Diet One | Two weeks |
Washout Period | Four weeks |
Diet Two | Two weeks |
Washout Period | Four weeks |
Diet Three | Two weeks |
Questionnaires for Hedonic Value and User Friendliness | End of experiment |
- Initial N: 36 males, no females in original study group
- Attrition (final N): 28 males finished the study
- Age: Range, 19 to 56 years; mean, 42.5±10.5 years
- Ethnicity: Men from the Netherlands.
Anthropometrics
- Subjects were matched for BMI, age, weight and blood glucose
- In addition to the above measurements, the following were recorded for each subject: Height, waist circumference, hip circumference, waist-to-hip ratio, body fat, systolic and diastolic blood pressure.
Location
This study took place at the Department of Human Biology, Maastricht University, Maastricht, The Netherlands.
Results of Variables
Variables | Results | Statistical Significance |
Body Weight | -4.4±0.7kg |
No significant difference between treatments |
BMI | -1.4kg/m2 | P<0.001 |
Waist and Hip Circumference |
-4cm |
P<0.001 |
Body Fat Percentage |
-3.8% | P<0.01 |
Blood Pressure
|
|
P<0.001 |
Blood Glucose | No change | |
Three-Factor Questionnaire:
|
|
P<0.01 |
SSM+ in First vs. Third Sequence | P<0.01 | |
SSM in First vs. Third Sequence | P<0.05 | |
SM, SSM+ SSM- vs. |
P<0.05 | |
Energy Intake (MJ/D):
|
|
|
Hunger |
|
|
Appetite: Estimation of How Much One Could Eat |
|
|
Satiety | Lower in SM, compared to baseline | P<0.05 |
Nausea
|
|
P<0.05 |
Flatulence
|
|
P<0.05 |
Hedonic Value of Semi-Solid Meal (0-5 Scale) |
3.8±0.1 | |
User-Friendliness (0-2 Scale)
|
|
P<0.001 |
Other Findings
- Body weight lost greatest during the first intervention period
- SSM+ and SSM- treatments resulted in an acute effect on body weight
- SM showed no difference in body weight loss, with respect to the different sequences
- Compliance was not related to body weight changes
- All treatments were effective, compared to baseline
- Complaints about diets were low.
- All meals with or without guar gum added were effective on body weight-loss, without effecting satiety negatively
- Semi-solid meals were relatively more advantageous with decreased energy intake with usual level of appetite scores
- Observed energy deficit was in line with expected intake reduction and body weight loss
- Intermittent treatment may be used advantageously for weight reduction or weight maintenence
- Scores for cognitive unrestrained eating increased during intervention, which is consistent with weight-loss
- Compliance was lower with solid meals than with semi-solid meals (subjects stated semi-solid meals were easier to prepare)
- Low-energy solid meals were best used at the beginning of treatment
- Irrespective of diet type, the first diet was most effective on body weight-loss, compared to the second or third diet. This is possibly due to motivation or previous weight loss on first diet.
Industry: |
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- Overall good study design testing with many diet variables over a reasonable length of time
- Sample size too small, which negatively affected statistical measures
- Not enough information regarding the subjects' previous health, health conditions, exercise habits, daily living habits or medications; all of which could affect weight-loss
- Discussion of blinding was not included in the article, except in the hydration study
- Computer-assisted nutrition analysis software is outdated (1988), which could lead to inaccurate diet assessment.
Quality Criteria Checklist: Primary Research
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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? | ??? | |
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? | No | |
2.2. | Were criteria applied equally to all study groups? | Yes | |
2.3. | Were health, demographics, and other characteristics of subjects described? | No | |
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? | ??? | |
3.3. | Were concurrent controls or comparisons used? (Concurrent preferred over historical control or comparison groups.) | ??? | |
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? | No | |
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.) | ??? | |
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? | N/A | |
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? | 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)? | ??? | |
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? | 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? | No | |