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Trial registered on ANZCTR

Registration number
Ethics application status
Date submitted
Date registered
Date last updated
Type of registration
Prospectively registered

Titles & IDs
Public title
How healthy adults determine food portion sizes
Scientific title
The effects of food cue manipulations on pre-meal planning and actual food intake in healthy adults
Secondary ID [1] 283130 0
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Portion size selection and food consumption 289981 0
Condition category
Condition code
Diet and Nutrition 290361 290361 0 0

Study type
Description of intervention(s) / exposure
Study design: Randomized, controlled, crossover design

Test foods:
1. Visual manipulations
a. Visible fat – energy-matched butter on toasted French bread
b. Visible sugar – energy-matched jam on toasted French bread
c. Visible protein – energy-matched ham on toasted French bread
d. Visible protein – energy-matched cream cheese on toasted French bread
2. Olfactory manipulations
a. Natural odour – plain mashed potato with Italian herbs
b. “Fat” odour – herbs + butter or bacon essence added to mashed potato
3. Food form manipulations
a. Solid – apple
b. Liquid – apple juice

Participants will be screened at baseline to confirm eligibility and baseline measurements will be obtained. If qualified, participants will attend eight 45-minute sessions to undergo all study conditions in a random order. Participants will be asked to avoid vigorous activity and drinking alcohol on the previous day, and fast for 10 – 12 hours prior to each session. Participants will arrive at the laboratory between 8am and 9am, and overnight fasting will be verbally confirmed by the researcher. Upon arrival, participants will be asked to drink 200ml of plain water (as a control for thirst and baseline hunger), and baseline appetite ratings will be assessed using validated visual analog scales (VAS) (Flint 2000) 5 minutes after water consumption. Test foods will be presented in large portion sizes (to avoid portion bias and to prevent plate-cleaning), and participants will be asked to take a portion of the test food that is expected to help them achieve a fullness level of 8 out of 10. Participants will also be asked to rate the appearance and intensity of smell of foods. Following that, the portioned food will be removed, and an identical plate of food will be presented to participants again. They will be given 30 minutes to consume the same food until a fullness level of 8 is achieved. After 30 minutes, participants will be asked to rate the palatability of the test foods, how often they will consume the same food again, and VAS again before leaving the lab. Participants will return until all conditions are completed.

The washout period between study visits will be at least 24 hours.
Intervention code [1] 287851 0
Other interventions
Comparator / control treatment
There is no control in this experiment, comparison will be done relative to other conditions.
Control group

Primary outcome [1] 290390 0
Expected satiation (as amount of food selected) in grams
Timepoint [1] 290390 0
At each feeding session
Primary outcome [2] 290471 0
Actual satiation (as amount of food consumed) in grams
Timepoint [2] 290471 0
At each feeding session
Secondary outcome [1] 304393 0
Food palatability ratings using visual analog scales

Timepoint [1] 304393 0
At each feeding session
Secondary outcome [2] 304568 0
Appetite ratings using visual analog scales
Timepoint [2] 304568 0
Before and after test meal consumption at each session

Key inclusion criteria
* Males and females
* Age 18-60 years
* BMI 18.5 – 35 kgm-2
* Not taking medications that affect metabolism or appetite
* Non-smokers
* Are familiar with test foods
* Willing to comply to study protocol
Minimum age
18 Years
Maximum age
60 Years
Both males and females
Can healthy volunteers participate?
Key exclusion criteria
* Presence of disease(s)
* Food allergies or intolerance

Study design
Purpose of the study
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Allocation is not concealed.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Order of foods received by each participant will be randomized using a computer software
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?

Intervention assignment
Other design features
Not Applicable
Type of endpoint(s)
Statistical methods / analysis
Based on our previous study with similar study design where food form was manipulated (beverage vs. solid) (Houchins 2012), consumption of challenge meals were 186 +/- 163 kcal for solid and 326 +/- 169 kcal for beverage preloads. Based on these, to detect an effect of similar magnitude in this proposed study at 80% power will require 12 participants (a=0.05) to complete the study. However, we anticipate the difference to be smaller between other test conditions (visual and olfactory manipulations). Food consumption data from other studies is not available, but a difference of 75 kcal between test meals within each manipulation is considered appropriate since it represent a difference of approximately one serving size of the test foods (bread and mashed potato). Using this expected difference, 40 participants are required to achieve statistical power of 80% at a=0.05.

Statistical analyses:
* One-way ANOVA
* Correlation
* Paired t-test

Recruitment status
Date of first participant enrolment
Date of last participant enrolment
Date of last data collection
Sample size
Accrual to date
Recruitment in Australia
Recruitment state(s)
Recruitment postcode(s) [1] 7303 0
5001 - Adelaide

Funding & Sponsors
Funding source category [1] 287881 0
Name [1] 287881 0
University of South Australia
Address [1] 287881 0
School of Pharmacy and Medical Sciences
City East Campus, North Terrace, GPO Box 2471
Adelaide SA 5001, Australia.
Country [1] 287881 0
Primary sponsor type
University of South Australia
School pf Pharmacy and Medical Sciences
City East Campus, North Terrace, GPO Box 2471
Adelaide SA 5001
Secondary sponsor category [1] 286608 0
Name [1] 286608 0
Address [1] 286608 0
Country [1] 286608 0

Ethics approval
Ethics application status
Ethics committee name [1] 289822 0
Human Research Ethics Committee
Ethics committee address [1] 289822 0
University of South Australia
City East Campus, North Terrace, GPO Box 2471
Adelaide SA 5001
Ethics committee country [1] 289822 0
Date submitted for ethics approval [1] 289822 0
Approval date [1] 289822 0
Ethics approval number [1] 289822 0

Brief summary
This study will provide useful data on the importance of three sensory characteristics possibly used by humans in meal planning. Knowledge in this area will then be incorporated as part of the overweight and obesity treatment, or in the prevention of weight gain. We hypothesize that visual, olfactory, and food form cues are important determinants of expected satiation and food portion size selection.
Trial website
Trial related presentations / publications
Public notes

Principal investigator
Name 42602 0
Dr Sze Yen Tan
Address 42602 0
School of Pharmacy and Medical Sciences
City East Campus, North Terrace, GPO Box 2471
Adelaide SA 5001
Country 42602 0
Phone 42602 0
+61 8 8302 1399
Fax 42602 0
Email 42602 0
Contact person for public queries
Name 42603 0
Dr Sze Yen Tan
Address 42603 0
School of Pharmacy and Medical Sciences
City East Campus, North Terrace, GPO Box 2471
Adelaide SA 5001
Country 42603 0
Phone 42603 0
+61 8 8302 1399
Fax 42603 0
Email 42603 0
Contact person for scientific queries
Name 42604 0
Dr Sze Yen Tan
Address 42604 0
School of Pharmacy and Medical Sciences
City East Campus, North Terrace, GPO Box 2471
Adelaide SA 5001
Country 42604 0
Phone 42604 0
+61 8 8302 1399
Fax 42604 0
Email 42604 0

No data has been provided for results reporting
Summary results
Have study results been published in a peer-reviewed journal?
Other publications
Have study results been made publicly available in another format?
Results – basic reporting
Results – plain English summary