Effect of Tableware Visual Cues on Portion Control and Eating Rate

Randomised within subjects cross-over study (n=94) exploring the cognitive and physiological processes associated with portion control. Participants will eat a self-served lunch using a portion control plate vs. a conventional (control) plate on two separate occasions under a controlled laboratory environment. Portion size, meal micro-structure, attention, memory and satiety markers will be analysed. The portion control plate is a prototype designed in collaboration with the commercial partner for this study and is based on published evidence. It includes sectors and pictures indicating amounts to serve from starchy food, protein and vegetables. The control plate will be of the same background colour, size and shape but without any pictures or demarcations. The main study outcome is attention time on areas of interest in the plate corresponding to main foods groups, across plate conditions.

The size and design of tableware have been proposed as a potentially effective strategy to modulate how much is eaten at a meal. The mechanisms by which specific tableware may work however are not known, in particular the cognitive processes associated with visual stimuli. In this covert trial, 68 women (34 overweight or obese) and 26 lean men (exploratory sub-study) will self-serve and consume food from a laboratory buffet using a portion control plate with visual stimuli for appropriate amounts of main food groups, or a conventional plate, on two different days in random order. On both sessions participants will complete behavioural and cognitive tests to measure visual attention during the meal (eyetracking device), meal microstructure (Universal Eating Monitor), episodic memory for portion sizes (computerised test), portion size choice, food intake, subjective appetite and satiety, cephalic and intestinal satiety responses. Further behavioural tests include meal liking, expected satiety, portion size perceptions and tool acceptance ratings. The main study outcome is difference in proportional dwell time on areas of interest in the plate corresponding to main foods groups (women), or difference in bite size (men) across conditions. Secondary outcomes for all subjects include: portion size for overall meal and meal components, eating rate, bite size, deceleration rate, portion size memory error, portion size norms, portion control self-efficacy, tool acceptance, energy compensation for the rest of the day, plus blood insulin, glucose, pancreatic polypeptide and ghrelin up to 90 min post-meal (sub-sample of 34 women, 50% being overweight/obese). Analyses by gender and BMI sub-groups will be applied when possible. The results of this study will help to better understand the potential mechanisms by which portion control tools with visual cues may work, and to improve the design of current instruments for their application in nutritional interventions.

Eligibility Criteria:
Inclusion Criteria:

1. Women and men aged 18-60 years.
2. For women, having a BMI between 18.5 and 35 kg/m2 (both included); for men having a BMI between 18.5 and 25 kg/m2 (both included).
3. Healthy as determined from the self-reported medical history or when a clinical condition exists, when this is considered to be irrelevant for the study by the study medical doctor.
4. Not taking any medication that may affect sight, gastro-intestinal function or appetite. Volunteers taking medication for clinical conditions that may affect the above functions will be eligible if they report no side effects and the dose has been stable for at least 3 months prior to commencement of the study.
5. Consuming breakfast and lunch regularly (at least 5 days per week).
6. Liking of the study foods defined by a score of \>40 mm of the Liking VAS questionnaire, for each compulsory meal component.
7. Able to consume food without the need for prescription glasses (contact lenses are allowed).
8. Able to understand and be willing to sign the informed consent form and to follow all the study procedures and requirements.

Exclusion Criteria:

1. Deficient nutrition or hydration status at the time of recruitment.
2. Abnormal gastro-intestinal function or structure such as malformation, angiodysplasia, active peptic ulcer, and chronic inflammatory or malabsorptive diseases, even if at the time of recruitment the volunteer is not taking medication for such conditions (e.g. anti-inflammatory drugs).
3. History of gastro-intestinal surgery with permanent sequels (i.e. gastroduodenostomy).
4. History of liver disease.
5. History of cancer or receiving treatment for cancer.
6. Diabetes mellitus.
7. Food allergy, food restriction or avoidance of any of the study foods (e.g. vegetarian).
8. History of mental illness, or being under active treatment for mental illness (e.g. psychiatric disorder), whenever their condition affects their ability to comprehend or follow the requirements of the study in full, or when their condition affects short-term memory (e.g. Alzheimer disease).
9. Presence of an eating disorder defined as a score \>19 on the Eating Attitudes Test (EAT-26).
10. Diagnosed or suspected epilepsy or photosensitive epilepsy (e.g. experiencing an "aura" or odd sensations while watching images or patterns on a computer screen).
11. Wearing a pacemaker or other medical electronic device.
12. Currently dieting to lose weight.
13. Smoking \> 7 cigarettes per week.
14. Consuming \>14 units of alcohol intake per week in women, or \>21 units per week in men.
15. Performing \>9 h of intense physical activity per week.
16. Pregnancy or lactation.
17. Having received formal portion size education as part of a university degree (e.g. Dietetics, Human Nutrition, Psychology if relevant).
18. Being familiar with the nature of the covert measures involved in the study (i.e. measure of eating speed and bite size).
19. Volunteers for which insufficient collaboration may be foreseen, or whom the investigator has grounds to believe that they may experience difficulty in following the study procedures.