Table 3 Detailed break-down of intervention content and incorporated BCTs

Scientific rationale

To understand the importance of diet and physical activity in the management of FH and for their overall health.

Information about health consequences, credible sources, biofeedback, information about emotional consequences, identification of self as a role model, comparative imaging of future outcomes

To be aware of the importance placed on diet and PA by national and international guidelines for FH and the current recommendations that all FH patients should receive individualised advice about diet & physical activity

To understand that the earlier treatment for FH starts, the more effective it is, and this is why it is important to optimise diet and physical activity from a young age

Dietary guidelines education

To increase knowledge of what a healthy balanced diet looks like, including the food groups and the proportion each one should make to diet

Instruction on how to perform behaviour, demonstration of the behaviour, behavioural practice/rehearsal, behaviour substitution, framing/re-framing

To increase knowledge of what the 5 dietary targets of the intervention are

To understand why each target is important for their health and for the management of their FH

To understand what foods to include/exclude and/or increase/decrease consumption of to achieve targets

Physical activity guidelines education

To increase knowledge of what the physical activity recommendations are for the individuals age

To increase knowledge of physical activity intensities (i.e. low, moderate and vigorous) and what types of activity fall into these intensity groups

To understand how to incorporate more physical activity into everyday life to help increase levels to recommended amounts (or more)

Goal setting

Work with the dietitian to develop SMART goals for each target behaviour. These will be changes to their lifestyle that they agree to make over the following 12 weeks to achieve nutritional intakes and PA levels closer to the targets.

Goal setting (behavioural), behaviour substitution, action planning, prompts and cues, Restructuring the physical environment, identification of self as a role model, Restructuring the social environment

Barriers and solutions

To identify potential barriers that may prevent individuals from meeting their goals

behaviour substitution, behaviour substitution, prompts and cues, Information about antecedents, Restructuring the physical environment, problem solving, Restructuring the social environment

To identify, through discussion with dietitian and family, solutions

Wrap up & instructions

An opportunity to ask any unanswered questions

Social support (emotional), verbal persuasion about capabilities

Receive encouragement & motivation from dietitian

To understand the purpose of the weekly reflection diaries and know how to fill them out

Follow-up sessions (weeks 2,4, 8 and 11)

To review with dietitian their progress towards goals set at previous session

Self-monitoring of behaviour, review behavioural goal(s), behaviour substitution, behaviour substitution, prompts and cues, Information about antecedents, Restructuring the physical environment, identification of self as a role model, problem solving, social support (practical), Social support (emotional), verbal persuasion about capabilities, Focus on past success, Feedback on outcomes of behaviour

To adjust goals accordingly, with help of dietitian, to facilitate attainment

Brainstorm solutions to any identified barriers to achievement recorded in reflection diaries

To receive encouragement and motivation from dietitian