Online Validation of Dietary Intake Food Frequency Questionnaire Over Four Weeks, and Electronic Device Use Questionnaire Over Eight Weeks.

L/Z FFQ Validation The validation procedure will span over four weeks, consisting of administering the L/Z FFQ and 24-hour diet recalls at multiple timepoints. Timepoints for the eight 24-hour diet recalls will be determined by random number generator for each of the participants at baseline (https://www.random.org/), of which two will take place on weekend days, and the remainder on week days.

• The weekly L/Z FFQ will be completed at the conclusion of each of the four weeks.
• The monthly L/Z FFQ will be completed at baseline and at the conclusion of week four.

Participants will indicate their consent to participate on Checkbox® by proceeding to the complete the questionnaires.

• Demographic information: at the beginning of the first investigation (monthly L/Z FFQ) participants will be asked to report their weight, height, age, gender, highest level of education, occupational status (employed or unemployed), post-code and country of residence, usual hours of physical activity per week, how they heard about the study, and whether they are actively trying to gain or lose weight. Personal information is to be collected to qualify the characteristics of the population in which the tool is being validated. Data collected via Checkbox ®.
• L/Z FFQ: The weekly L/Z FFQ is a 91-item questionnaire that takes approximately 20 minutes to complete, and investigates the frequency of intake of listed foods or supplements over the prior seven days. The monthly L/Z FFQ contains the same 91 items, takes approximately 30 minutes to complete, and investigates the frequency of intake of listed foods or supplements over the prior month. In addition, the monthly L/Z FFQ contains four qualitative questions that investigate change in usual dietary intake over the last one to ten years. Questionnaire data collected via Checkbox®.
• 24-hour diet recall: the diet recall via the online Automated Self-Administered 24-Hour Dietary Assessment Tool (ASA24®) takes approximately 25 minutes to complete, and investigates food and beverages consumed in the prior 24-hours (20). The ASA24® is supported by the National Institutes of Health (NIH) in the United States (US) with national variants and as a US government entity not within the EU-US Data Privacy Shield for legal reasons. Therefore, explicit consent for use of the ASA24® tool will be sought from participants. For further information on the tool: https://epi.grants.cancer.gov/asa24/.

EDUQ Validation

The validation procedure will occur over eight weeks consisting of administering eight 24-hour diary of ED use (24-hour ED use diary) and the EDUQ at three time points. The time points for the eight 24-hour ED use diaries will be determined by random number generator for each of the participants at baseline (https://www.random.org/), of which two will take place on weekend days, and the remainder on weekdays. The EDUQ will be completed at baseline and at the conclusion of weeks four and eight. Upon consenting to participate on the Checkbox® by proceeding to the questionnaires, participants will be instructed to fill out:

• The EDUQ: A 22-item questionnaire that takes 20 minutes to complete, and measures participant demographic information (weight, height, age, highest level of education, occupational status, post-code and country of residence), usual daily ED use from present up to 20 years ago, occupational influence to use, and differences to ED use between a weekend and weekday (questionnaire adapted from Williams et al. (2019) (21). Personal information collected as part of this questionnaire is to qualify the characteristics of the population in which the tool is being validated. Data collected via Checkbox®.
• 24-hour ED use diary: Participants will be asked to record their ED use in hours and minutes over 24 hours. Data collected via Checkbox®.

Inclusion criteria

• Healthy males and females 18 years and over.
• Access to an ED such as a computer, phone, or tablet, and internet to complete investigations.

Exclusion criteria

• Visual, hearing, or physical impairment that may prevent from completing investigations.
• No English literacy.