EAL

NNNS: Appetite (2006)

Citation:

Study Design:

Class:

- Click here for explanation of classification scheme.

Quality Rating:

Research Purpose:

To examine whether sugar-rich vs. sugar-free drinks have a greater suppressive effect on appetitie and food intake and also whether the pleasant sensory experience of sweet beverages stimulates appetite and food intake to a greater extent than plain water.

Inclusion Criteria:

Male university students
Ages 19 to 30
Never dieted nor were excessively concerned with their eating habits or body weight, as determined by an interview and scores of less than 10 on the Three-Factor Eating Questionnaire.
moderately active and reported their weight had been stable for the last year or more.
no medications or famiy history of obesity or diabetes
ate breakfast daily and frequently consumed potato crisps and regular and sugar-free soft drinks.

Exclusion Criteria:

female subjects

Description of Study Protocol:

Recruitment All subjects signed informed consent forms and was approved by Ethical Review Committee of the University of Sydney.

Design

A within-subjects repeated measures design was done.
Each subject was their own control.

Blinding Used

Subjects were initially told that the study was investigating the effects of soft drinks on moods and alertness.

Intervention

Three pre-load drinks were tested: Plain carbonated mineral water, sugar-rich soft drink, sugar-free soft drink. Each pre-load was served in a 375ml portion in a large glass with crushed ice to mask flavors and represent the volume in a can.
The three pre-loads were consumed in random order on separate mornings, one week apart and the order of presentation was done by incomplete block design. The timing of meaurements is in the data collection summary.

Statistical Analysis

Food diaries were analyzed by a dietitian and calculated by manufacturers' data and software Diet 3.21 Australian Food Tables. Time-response curves were constructed for the hunger and fullness VAS ratings. The incremental area under each time-response curve (AUC) was calculated using the trapezoidal rule with fasting values as the baseline and truncated at zero.
Significant differences in VAS ratings and food intake responses were analysed using two-way repeated-measures ANOVA.
The Fischer PLSD Test for Multiple Comparisons was used as a post hoc test to detect any significant differences among mean appetite and food intake responses for the pre-loads.
Linear regression analysis was used to test the significance of associations of pre-loads and appetite and food intake responses.

Data Collection Summary:

Timing of Measurements

Before start of study: Individual tutorial and information sheets fully outlining all of the experimental procedures were given.
Subjects were instructed to maintain regular exercise and eating patterns throughout the study and to refrain from alcohol and social events during the day before a test and during each test day.
Subjective ratings: Alertness, calmness, agitation, hunger and fullness were assessed by repeated aministration of 100mm visual analog rating scales (VAS). Table One experimental timetable. All ratings were collected after they were completed in order to prevent the subjects referring to their previous ratings.

Timing of Experimental Procedures


Time	Procedure
Night Before Test	Overnight Fast (10 to 12 hours)
Test day
8:00 a.m.	Consume standard breakfast
10:00	Arrive at laboratory
	Complete VAS baseline ratings
10:10	Consume pre-load
	Complete palatability and post-pre-load VAS ratings
10:20	Large bowl of chips for each subject, subjects free to consume as desired
10:35	VAS ratings, new bowl of crisps to consume
10:50	VAS ratings, new bowl of crisps to consume
11:05	VAS ratings, new bowl of crisps to consume
11:20	VAS ratings, new bowl of crisps to consume
11:35	VAS ratings, new bowl of crisps to consume
11:50	Pre-lunch VAS ratings
	Individuals provided with a tray of standard lunch items (wholegrain and white bread, butter, ham, processed meat, cheese, lettuce, tomato, cucumber, choclate chip biscuits, apples, fruit juice, tea, coffee, milk)
	Subjects' ad libitum food intake was covertly recorded
12:20 p.m.	Subjects leave and complete weighed food diary the rest of the day

Description of Actual Data Sample:

Initial N: 11 healthy normal-weight men
Attrition (final N): 11
Age: 19-30
Other relevant demographics: Sydney, Australlia.

Summary of Results:

Pre-load palatability ratings: Mean palatability ratings for the three pre-loads was not significantly different. The plain mineral water had the lowest average.

Inital post-preload appetite ratings (15 minutes): Over the 100-minute experimental period, the high-energy, sugar-rich drink initially suppressed hunger to a greater extent than both the low-energy, sugar-free soft drink and mineral water, but the differences were not significant. The three pre-loads initally increased fullness ratings to the same extent.

Potato crisp intake: There were no significant differences in crisp consumption, except during the 35- to 50-minute time period, when signifcantly fewer crisps were consumed after mineral water pre-load than the sugar-free drink (P<0.05).

Relationships between appetite ratings and potato crisp consumption: There were no significant differences among the pre-loads in the mean fullness or hunger AUC values for the 110-minute period as well as per kJ.

Food intake at lunch: Pre-lunch hunger ratings at 110-minutes were not significantly related to the weight of food or energy consumed at lunch. Fullness or hunger AUC values were also not significantly associated with food intake at lunch. No significant differences in total weight of food and drink consumed at lunch or total amount of energy and fat consumed.

Total day nutrient intakes: No significant differences among the pre-loads in the amount of food consumed after lunch. Small but non-significant differnces in total day energy and macronutrient intakes. When measured in grams, total day fat intakes were not significantly related to total sugar or carbohydrate intakes. When expressed as a percentage of total day energy intake, total fat intake was inversely related to total carbohydrate intake, but was not significantly associated with total sugar intake.

Author Conclusion:

The low-calorie, low-sugar drinks did not facilitate reduced energy intake by the lean non-dieting male subjects.
The available data indicates that low-calorie sugar substitutes could facilitate the consumption of dietary fat, if people choose sugar-free products to justify the consumption of larger portions of high-fat foods or if subsequent food intake increases in general.

Limitations

It is possible that not enough carbohydrates from the sugar-rich pre-load was absorbed during the 20-minute interval between the pre-load and crisp availability to produce the maximum possible increase in satiety.
Also, there may not have been enough carbohydrates (41g) in the sugar-rich pre-load to enhance satiety significantly within this short time period.
Further research is required to compare the satiating effects of sugar-rich vs. sugar-free products in lean and overweight subjects, males and females and restrained eaters.

Funding Source:

University/Hospital:

Human Nutrition Center University of Sydney

Reviewer Comments:

No anthropometic data was given, even though reported men were healthy and of normal weight.

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?	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?	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?	N/A
	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?	Yes
	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?	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)?	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?	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