Table 1 Guiding principles for intervention development describing the key behavioural issues, design objectives and intervention features and components

1) Denial of risk and low motivation to engage with lifestyle change:

Older adults unaware or unwilling to acknowledge personal risk of malnutrition and its impact on health and wellbeing. Numerous physical and social barriers to eating well.

Motivate engagement with lifestyle change

• Provide credible evidence-based rationale

• Dispel myth that decline in appetite and eating, and weight loss are normal and inevitable in older age

• Clarify that everyone can be at risk of malnutrition

• Outline that mainstream public health messages (e.g. low fat, low sugar) may be less appropriate for those with low appetite or unintended weight loss

• Demonstrate empathy and acknowledge real barriers to changing eating behaviour

2) Low self-efficacy to overcome physical and social barriers to eating well and make long-term changes, particularly resignation to age-related decline

Promote self-efficacy to manage malnutrition risk, and overcome barriers to eating well

• Positive tone to encourage beliefs about being able to overcome barriers

• Align behavioural advice and support with need to be ‘well’ and ‘independent’

• Provide examples of small, easy to enact lifestyle-compatible changes

• Allow self-tailoring to address personal barriers e.g. strategies for those who dislike eating alone

• Offer longitudinal motivational support e.g. ongoing nurse appointments to encourage self-care

• Support motivation in-the-moment e.g. suggest using visual cues (biscuit tin near kettle) to encourage eating between meals

• Support personal goal and action planning

• Provide stories to model successful ways to overcome barriers

3) Rejection of imposed lifestyle change that contradicts existing knowledge, values and preferences, including desire to remain independent

Promote support and autonomy for choosing lifestyle changes that harness personally relevant motivations

• Present rationale for lifestyle change with a non-directive tone

• Present behavioural suggestions as options to try

• Invite expression of preferences e.g. possible reasons for wanting to eat well, with tick boxes for self-selection

• Acknowledge and validate existing knowledge and experience before introducing new information and advice