Widely used in teaching various healthcare students, patient simulations are not common in dietetics education. This mixed-methods study investigated effectiveness of patient simulations in two courses (one undergraduate, one graduate) in 2016 and 2017 in Applied Human Nutrition at the University of Guelph. Nutrition students acted as dietitians, and theatre students as patients. 99.8% of undergraduate and 82.6% of graduate nutrition students agreed/strongly agreed that simulations enhanced learning and confidence. Undergraduate students’ competence scores related to physical assessment, patient education, and communication skills improved by 46.9%, and graduate students’ scores related to assessment, patient education, communication and counselling skills, by 27.9% (both p < 0.01). Thematic analysis of students’ written reflections and focus group data suggested simulations increased communication and assessment skills, confidence and self-efficacy. Simulation realism, student preparedness, observing, post-simulation debriefing and reflecting increased perceived simulation value. Strengths, limitations, and clinical and pedagogical implications of simulation are discussed.