Introduction: Health professionals (HPs) working in primary care play a critical role in counselling patients to make diet-related behaviour changes. However, little research has been conducted on how HPs perceive to influence patients’ lifestyle behaviours. 
Objectives: To understand how HPs perceive to influence patients’ dietary behaviours. 
Methods: Semi-structured interviews were conducted with 33 HPs (7 family physicians [MD], 13 nurse practitioners [NP], and 13 dietitians [RD]) in multidisciplinary healthcare settings. Interviews were audio-recorded and transcribed verbatim. Thematic analysis was used to inductively elucidate Themes and subthemes.
Results: Themes: 1) Degree of influence, 2) strategies to support patients in changing their lifestyle behaviours, and 3) practitioner’s role. Most HPs believed to have a positive influence on patients’ lifestyle behaviours. However, many acknowledged there are uncontrollable factors influencing dietary behaviours. MDs reported having influence on patients’ lifestyle behaviours. NPs and RDs reported using strategies like motivational interviewing. HPs employed various strategies to support patients in changing lifestyle behaviours including: leading by example, motivational interviewing, and helping patients set realistic goals. HPs’ main role seemed to include identification and discussion of barriers to lifestyle changes.
Conclusion: Most HPs perceived to have a positive influence on patients’ lifestyle behaviours. HPs acknowledged external factors hindering changes in dietary behaviours and discussed various support strategies. Strategies included discussing barriers and using motivational interviewing. Although uncontrollable factors and barriers, like unexpected life events or readiness for change, may affect patients’ success to change lifestyle behaviours, HPs perceived to have an important role in discussing these barriers, while providing individualized care. 
Significance to the field of dietetics: Understanding how HPs perceive their ability to influence patients’ dietary changes will influence their decision to initiate counseling. Our findings indicated most HPs perceived to have a positive influence on patients while highlighting barriers encountered and strategies to address them.

Perceived influence: The role of health professionals on patients’ lifestyle behaviours