Table 1.

Intervention mapping of behaviour change techniques to theoretical constructs^{( 33 )} (numbers in CALO-RE taxonomy^{( 34 )} in square brackets, numbers in v1 taxonomy^{( 35 )} in parentheses)

Theoretical construct	Behaviour change technique (number in v1 taxonomy) [number in CALO-RE taxonomy]	Implementation strategy
Risk perception	Provide information on consequences of behaviour to the individual [2]	∙Individualized risk feedback on self-reported abdominal girth (What does your waistline ratio tell about you?) ∙Individualized risk feedback on vessel calcination (How does a Mediterranean diet affect your body?)
Outcome expectancies	Provide information on consequences of behaviour in general [1]	∙Interactive quiz on nutritional facts and myths about nutritional content of several foods (Sherlock Holmes Quiz) ∙Interactive quiz on the Mediterranean pyramid (What do the Egyptians have to do with nutrition?)
	Pros and cons (9·2)	∙Open text fields to enter up to six advantages of engaging in a Mediterranean diet for a comic character (Convince Sporty the frog to eat more healthily) ∙Open text fields to enter up to three short-term and three long-term positive consequences of a Mediterranean diet for oneself ∙Open text field to enter up to three disadvantages of a Mediterranean diet for oneself ∙Reappraisal of the disadvantages by generating positive outcomes (preceded by three examples)
Self-efficacy	Prompt self-talk (15·4)	∙Open text field to enter a motivating sentence to eat more healthily
	Prompting focus on past success (15·3)	∙Introduction of three tempting situations, participants could choose whether they had managed to resist these situations in the past (Can I resist temptations?) ∙Open text fields to document own nutritional success story (Are you ready for the nutrition challenge?)
	Vicarious reinforcement (16·3)	∙Provision of examples of success stories if participant did not recall any mastery experience (tailored to gender of participant)
Planning	Action planning (1·4)	∙Goal setting ∙Weekly online planner ∙Pop-up windows to specify nutritional component, number of servings, location and occasion (e.g. after work)
	Problem solving/coping planning (1·2)	∙Identification of potential barriers/challenging situations (self-generated) and ways to overcome them (self-generated; if none mentioned, examples provided)
Action control	Prompt self-monitoring of behaviour (2·3)	∙Weekly review of online planner ∙Slidebar to rate one’s success (0–100 %) of enacting action plans ∙Enter alternative behaviours if action plans were not met