Clinician-rated depression symptoms will be assessed using the Children's Depression Rating Scale Revised (CDRS-R). The CDRS-R, a semi-structured clinical interview which takes 15-20 min to administer, is a widely used interviewer-administered rating scales for measuring depression symptoms in intervention studies of adolescent depression. The measure assesses depression symptoms, rated on 5- to 7-point Likert rating scales. Depression symptom domains are aligned with the diagnostic criteria for depression and include sleep disturbance, excessive fatigue, suicidal ideation, and social withdrawal. Participants are asked about information on 14 items. Youth will complete this measure.

The 'KIDMED2' questionnaire will evaluate dietary intake in relation to the Mediterranean Diet in children and adolescents. KIDMED2 is a 16-item questionnaire that can be self-administered or conducted by an interview with responses being yes/no. Items related to lower adherence are assigned a value of -1 (4 items) and those related to higher adherence +1 (12 items). Scores range from 0-12. A total score of ≤ 3 is considered poor adherence; a score of 4-7 is considered medium adherence and ≥8 is high adherence. Youth will complete this measure.

The National Cancer Institute's Automated Self-Administered 24-Hour (ASA24) Dietary Assessment is a validated tool that employs the Automated Multiple-Pass Method and is freely available in the public domain. Usual or habitual dietary intake requires two ASA24 dietary intake measures one during the week and another on a weekend day. Reported energy intake (rEI) and nutrient intakes will be generated automatically by the ASA24 software using the ASA24-Canada-2018 version, released in April 2019 and food composition data from the Canadian Nutrient File as well as data from the Food and Nutrient Database for Dietary Studies. Youth will complete this measure.

The Food Choice Questionnaire is a 36-item self-administered questionnaire that evaluates factors which influence dietary choices. Factors which might influence food choices are divided into 9 subscales, which are labelled health, mood, convenience, sensory appeal, natural content, price, weight control, familiarity and ethical concern. Items are scored on a 4-point Likert scale ranging from 1 (not important at all) to 4 (very important). Higher subscale scores reflect a greater emphasis on that particular factor when selecting foods. Youth will complete this measure.

Diet satisfaction will be assessed using the Diet Satisfaction Score (DSS), a comprehensive tool consisting of 10 items focused on measuring a singular dimension. The DSS demonstrates strong reliability through a robust intraclass correlation coefficient of 0.64. Moreover, the minimal mean difference (95% confidence interval, CI) between repeated test scores stands at 0.03 (-0.02, 0.09), affirming its stability. Participants rate their level of agreement on a 5-point Likert-type scale across the 10 statements, spanning from 'strongly agree' to 'strongly disagree.' Higher scores on this scale directly correlate with greater satisfaction with the diet. Calculated as the mean of all items, the total score ranges from 1 to 5, with 5 signifying optimal satisfaction. Higher scores indicate a stronger sense of satisfaction with the diet. Youth will complete this measure.

The International Physical Activity Questionnaire for Adolescents (IPAQ-A) is a self-reported questionnaire that measures physical activity (PA) in the last 7 days. Participants will estimate the number of occasions per week for activities such as sitting, walking, leisure cycling, running and/or aerobics. The total number of days and minutes of PA will be reported as metabolic equivalent of task (MET) per hour per week, with greater METs indicating greater physical activity. Using the IPAQ scoring protocol, PA will be reported as a continuous variable - the metabolic equivalent of task (MET) minutes per week and as a three-level categorical variable (using IPAQ-A cut-points): low level of activity; moderate level of activity; or high level of activity. Youth will complete this measure.

Eating behaviour will be assessed with The Dutch Eating Behavior Questionnaire (DEBQ), a 33-item self-report questionnaire to comprises three scales assessing restrained eating (DEBQ-R), emotional eating (DEBQ-E), and external eating (DEBQ-X) behaviour. Items on the DEBQ range from 1 (never) to 5 (very often), with higher scores indicating greater endorsement of the eating behaviour. A score of 15 or higher indicates a risk for depression in children and adolescents. The scale has demonstrated good to excellent internal consistency (α = 0.84 - 0.92) and factorial validity. Youth will complete this measure.

The Pittsburgh Sleep Quality Index (PSQI) is a self-reported questionnaire designed to assess sleep quality and disturbances within a one-month timeframe. It comprises 19 individual items contributing to the calculation of seven "component" scores each scored 0 (no difficulty) to 3 (severe difficulty): subjective sleep quality, sleep latency, sleep duration, habitual sleep efficiency, sleep disturbances, use of sleeping medication, and daytime dysfunction. The sum of these seven component scores yields one global score ranging from 0 to 21 with the higher total score indicating worse sleep quality. In distinguishing between good and poor sleepers, a global PSQI score > 5 yields a sensitivity of 89.6% and a specificity of 86.5%. Youth will complete this measure.

Parental food modelling is evaluated with 10 items adapted from Cullen's scale, each rated on a four-point Likert scale from 'Never' (0) to 'Always' (3) which has been used to predict diet outcomes in adolescent samples. Higher scores signify greater healthful parental food modeling, with a maximum score of 30. Youth will complete this measure.

Satisfaction with menu planning is evaluated through a single item, independently assessed by parents and adolescents using a five-point Likert scale that ranges from 'very dissatisfied' (1) to 'very satisfied' (5). Parents and youth will complete this measure.

Satisfaction with nutrition counseling sessions is evaluated through a single item, independently assessed by parents and adolescents using a five-point Likert scale that ranges from 'very dissatisfied' (1) to 'very satisfied' (5). Parents and youth will complete this measure.

The Nutrition Attitudes and Knowledge (NAK) questionnaire is a brief questionnaire developed by a team of educators and dietitians to assess knowledge of the 2019 Canada Food Guide. We have adapted the NAK for this study. The adapted NAK questionnaire contains 22 items, with one section evaluating nutrition attitudes and four sections assessing nutrition knowledge associated with the different food groups. The nutrition attitudes section contains four 5-point Likert scale questions (e.g., "Eating healthy now can help me be healthy in the future"), with higher scores indicating more positive attitudes about nutrition. Thirteen multiple choice and five true/false questions were developed to reflect knowledge of the CFG food groups: Drinks, Whole Grain Foods, Vegetables and Fruit, and Protein foods (both animal and plant-based). Parents and youth will complete this measure.

The Questionnaire for Screen Time of Adolescents (QueST) is a self-reported questionnaire to assess screen time on a typical day. Participants are asked how much time they spend on screens across five constructs: studying, working/internship-related activities, watching videos, playing games, and using social media/chat applications on weekdays and again on weekends. Items are summed to obtain total weekday and weekend screen time. The QueST test-retest intra-class correlation coefficients range from 0.76 for social media use on weekdays to 0.24 for watching videos on weekends. Youth will complete this measure.

The Family and Nutrition and Physical Activity (FNPA) screening tool is a behaviorally-based assessment designed to allow parents to evaluate the family food environment and practices. FNPA has been extensively used in child and adolescent obesity research but also in studies examining diabetes prevention, family eating behaviour and cardiovascular risk factors.

The FNPA is a 20-item screening tool with 10-constructs. Parents are asked to rate their child's behaviour on a 4-point Likert scale ranging from almost never to very often. 6 items are reverse scored for the following questions and construct 3-Family Eating Practices, 4- Family Eating Practices, 5-Food Choices, 7-Beverage Choices, 10-Restriction/Reward, 13-Healthy Environment. Higher scores reflect more healthy home environments since no cut points or thresholds have been established for determining healthy vs unhealthy home environments. Parents will complete this measure.

Screen for Child Anxiety Related Disorders (SCARED) and the Revised Children's Anxiety and Depression Scale (RCAD) contains 41 items and measures rated on 3-point Likert-type scale anxiety using four domains: panic/somatic, separation anxiety, generalized anxiety, and school phobia with three possible responses ranging from ' not true or hardly ever true' to very often true or often true'. Parents will complete this measure.

The Revised Child Anxiety and Depression Scale - Parent Version (RCADS-P) is a 47-item self-report questionnaire with subscales including separation anxiety disorder (SAD), social phobia (SP), generalized anxiety disorder (GAD), panic disorder (PD), obsessive-compulsive disorder (OCD), and major depressive disorder (MDD). It also yields a Total Anxiety Scale (sum of the 5 anxiety subscales) and a Total Internalizing Scale (sum of all 6 subscales). Items are rated on a 4-point Likert scale from 0 ("never") to 3 ("always"). Parents will complete this measure.