Table 3.

Research outcomes and internal consistencies

Demographics	Age, gender identity, ethnicity, race, state and region of residence	T1
Primary outcomes
State body satisfaction	A single 11-point scale assessing the immediate impact of a chatbot technique on participants’ state body satisfaction (How satisfied are you with your appearance, right now, in this moment?). Total score range 0 (not at all) to 10 (very much). Higher scores reflect greater satisfaction.	Start of chatbot experience. Post-intervention technique. 12-, 16-, 23.5-h after non-engagement.
Trait body satisfaction	Body Esteem Scale for Adolescents & Adults in Brazil [46, 47]. Appearance Positive (AP; e.g., I like how I look like in photos), Appearance Negative (AN; e.g., I feel ashamed about my appearance) and Weight (e.g., I am satisfied with my weight). Mean subscale scores range between 0 (never) and 5 (always). Higher scores reflect higher esteem. Internal consistency: AP = .85; AN = .88; Weight = .89.	T1- T4
Secondary outcomes
State affect	A single 11-point scale assessing the immediate impact of a chatbot technique on participants’ state affect (How happy are you, right now, in this moment?). Total score range between 0 (not at all) to 10 (very much). Higher scores reflect greater positive affect.	Start of chatbot experience. Post intervention technique. 12-, 16-, 23.5-h after non-engagement.
Trait affect	The Positive and Negative Affect Scale for Children 8-item; PANAS-C8 [48] 8-items related to emotive states (4 positive [e.g., joyful]; 4 negative [e.g., irritated]). Positive and negative affect subscale scores range between 1 (not at all) and 5 (extremely). Higher scores reflect greater positive or negative affect. Internal consistency: PA = .77; NA = .76	T1 - T4
Trait body image self- efficacy	A purpose-built measure, The Body Image Self-Efficacy Scale, derived from existing self-efficacy measures [49–51]. 5 visual analogue scales (VAS; 0 [not at all confident] to 100 [very confident]) assessing participants’ belief in their ability to execute strategies to improve their body image (e.g., I am able to learn and practice new skills to help improve my body image). Total mean scores range between 0 and 100. Higher scores reflect greater body image self-efficacy. Internal consistency: .82	T1 - T4
Intervention adherence	Digital metrics will assess participants engagement with the chatbot, including: • Percentage of participants who complete the intervention (e.g., minimum of 1 technique completed over the 72-h intervention period); • Percentage of participants who enter the intervention but do not complete the intervention; • Percentage of participants who complete each intervention technique; • Average number of techniques completed; • Average length of time taken to complete each technique; • Average length of time spent engaging with the chatbot over the 72-h period.	72-Hour Intervention Period
Intervention acceptability	11 items assessed participants acceptability of the chatbot. Factors included: • Emotive response to the chatbot (e.g., enjoyment, interest, comfortability); • Relevance (e.g., pertinence, importance and helpfulness of the content to the user and other young people in Brazil); • Ease of use (e.g., speed and accuracy of responses); and • Willingness to recommend (e.g., how likely the user would recommend Topity to a friend and re-engage in the future). Item scores range between 1 (e.g., not at all enjoyable) and 7 (e.g., very enjoyable). Higher scores reflect greater acceptability.	T4

Note. T1 = Baseline; T1 = Baseline; T2 = Post-intervention; T3 = One-Week Follow-Up; T4 = One-Month Follow-up