EAL

DF: Obesity (2008)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

Study One: To determine whether one week of fiber (guar gum) supplementation (40g per day; 20g, bid), under free-living conditions, decreased energy intake or hunger and feelings of satiety in 17 obese women
Study Two: To determine the effect of one week of fiber (guar gum) supplementation (20g per day; 10g, bid) at normal (six mJ) and low (four mJ) levels of energy intake on feelings of hunger and satiety in 14 overweight women.

Inclusion Criteria:

Study One: Recent weight-loss of approximately 10kg body weight during a two-month VLCD program (three months prior to study start)
Study Two: Recent weight-loss of approximately 10 kgbody weight during a two-month VLCD program (three months prior to study start).

Exclusion Criteria:

None provided.

Description of Study Protocol:

Recruitment

Methods not provided, except to state that women who had recently been on a VLCD were chosen because of hypothesis that subjects should be more prone to weight-gain after this diet.

Design

Study One: Randomized crossover design, where subjects studied for two one-week periods. Fiber supplementation was randomized across subjects between the first and second weeks.
Study Two: Randomized crossover design, where subjects were randomized to two fixed levels of energy intake, with and without fiber supplementation, for one week each.

Blinding Used

None.

Intervention

Study One: 20g guar gum fiber in powder form, mixed with orange juice twice a day (40g per day) for one week vs. orange juice-only for one week (each subject participated in two one-week study periods)
- Orange juice (with or without fiber) consumed between meals at 3:30 pm and 8:00 pm.
StudyTwo: 10g guar gum fiber in powder form, mixed with orange juice twice a day (20g per day), along with either a normal-energy diet (six mJ) or a low-energy diet (four mJ) for one week vs. orange juice-only, with either a normal-energy diet (six mJ) or a low-energy diet (four mJ) for one week (each subject participated in four one-week study periods).
Four-mJ menu contained 21% protein, 24% fat, 55% CHO, 19g fiber
Six-mJ menu contained 19% protein, 28% fat, 53% CHO. 21g fiber
Orange juice with and without fiber was consumed between meals at 3:30 pm and 8:00 pm.

Statistical Analysis

Two-way ANOVA (repeated measurements)
Data presented as mean and standard errors of the mean (SEM)
Paired T-test, used in Study Two because data sets incomplete for ANOVA.

Data Collection Summary:

Timing of Measurements

Study One
- Participants rated hunger and satiety during the last three days of each week at fixed times during the day:
  - Before (7:00 am) and after (7:30 am) breakfast
  - Between breakfast and lunch (10:30 am)
  - Before (12:00 noon) and after (12:30 pm) lunch
  - Afternoon between lunch and dinner (3:30 pm)
  - Before (6:00 pm) and after (6:30 pm) dinner
  - Evening (8:30 pm).
- Dietary intake was recorded by participants in a food intake diary during the last three days of the week of study and analyzed by a computer program for energy and macronutrient intake. Food diaries were checked for under-reporting and household attributes and portion size were examined to check the amount of food consumed.
Study Two
- Participants rated hunger and satiety during the last three days of each of the four weeks at fixed times during the day:
  - Before (7:00 am) and after (7:30 am) breakfast
  - Between breakfast and lunch (10:30 am)
  - Before (12:00 noon) and after (12:30 pm) lunch
  - Before and after orang juice (±fiber) in the afternoon (3:00 pm)
  - Before (6:00 pm) and after (6:30 pm) dinner
  - Before and after orange juice (±fiber) in the evening (8:00 pm).
- Compliance to menus were checked. Subjects recorded intake during the last three days of each of the four weeks, indicating which foods were not eaten or were consumed in larger quantities than on menu and intake was analyzed by a computer program. (RDs instructed participants how to fill out the food diary).

Dependent Variables

Study One
- Hunger: Subjects rated hunger on a scale from "very hungry" to "not hungry at all"
- Satiety: Subjects rated satiety on a scale from "very satiated" to "not satiated at all"
- Energy intake: Food intake was recorded by participants in a food diary and analyzed for energy and macronutrient intake by a computer program.
Study Two
- Hunger: Subjects rated hunger on a scale from "very hungry" to "not hungry at all"
- Satiety: Subjects rated satiety on a scale from "very satiated" to "not satiated at all."

Independent Variables

Fiber supplementation (water soluble fraction and partially hydrolyzed guar gum, Benefiber, in powder form) mixed with 200ml orange juice, twice a day (afternoon and evening)
Study One: 20 grams fiber, bid (40g per day) plus 200ml orange juice with fiber; 308kJ, one gram protein, no fat, 17.4g CHO, 1.6g orange fiber and 20g guar gum
Study Two: 10g fiber, bid (20g per day).

Control Variables

Age
Weight
BMI.

Description of Actual Data Sample:

Initial N

Study One: 17 women
Study Two: 14 women.

Attrition (Final N)

Not given.

Age

Study One: 38.5±2.3 years
Study Two: 44.5±1.8 years.

Ethnicity

Not given.

Other Relevant Demographics

None given.

Anthropometrics

Study One: BMI, 32.2±0.9kg per m²
Study Two: BMI, 29.0±0.9kg per m².

Location

Maastricht University, The Netherlands.

Summary of Results:

Study One

Energy intake was significantly lower during three fiber-supplemented days (5.4±0.24mJ) than during the control days (6.7±0.39mJ) F(1,48)=8.32; P<0.05
No significant differences in hunger and satiety ratings during fiber-supplemented and control days
- Hunger: F(1,73)=0.007; P>0.9
- Satiety F(1,73)=2.67; P=0.11.

Study Two

Hunger scores were significantly lower on the six-mJ menu than the four-mJ menu without fiber supplementation, F(1,65)=3.94; P=0.05
Hunger and satiety scores were the same with and without fiber supplementation on the six-mJ menu, F(1,51)=0.26; P=0.61
No significant differences in hunger or satiety scores on the four-mJ menu with and without fiber supplementation, F(1,73)=0.88; P=0.35 for hunger; F(1,70)=1.85; P=0.18 for satiety; according to a two-way ANOVA
- Data sets not complete for ANOVA, so paired T-tests were done to determine differences between time points.
Time points that significantly differed for hunger
- 7:00 am: T=3.42; P<0.01
- 12:00 noon: T=2.33; P<0.05
- 8:00 pm: T=2.38; P<0.05
- 8:30pm: T=2.23; P<0.05.
Time points that significantly differed for satiety
7:00 am: t=3.34; P<0.01
12:00 noon: T=2.50; P<0.05
8:30pm: T=2.10; P<0.05.

Other Findings

In Study One, two subjects complained of flatulence during the fiber-supplemented weeks.

Author Conclusion:

Fiber supplementation under free-living conditions reduced energy intake and fiber supplementation reduced hunger at a low energy intake level (four mJ)
Fiber supplementation is effective for consuming a low-caloric diet spontaneously without feelings of hunger
These findings suggest that soluble fiber may be beneficial in weight maintenance by facilitating compliance to a low-caloric intake level, if it can be consumed daily over the long term.

Funding Source:

Industry:

Sandoze Nutrition (Sweden)

Pharmaceutical/Dietary Supplement Company:

Reviewer Comments:

Compliance to menu method in this short-term study was high (95% to 99%)
Fiber supplementation in sachets enabled subjects to prepare the orange juice drink anywhere.

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?	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)	No
	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%.)	No
	4.3.	Were all enrolled subjects/patients (in the original sample) accounted for?	???
	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?		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?		No
	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?	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?	???
	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)?	No
	8.6.	Was clinical significance as well as statistical significance reported?	No
	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?		Yes
	10.1.	Were sources of funding and investigators' affiliations described?	Yes
	10.2.	Was the study free from apparent conflict of interest?	Yes