Background <p>People ascribe mental function to and place more emphasis on the brain than the rest of the body in mental health care. Here, we sought to understand whether this brain-body dualism extends to 1) beliefs about how much people can change their “brain” vs. their “body” and how these beliefs map onto attitudes towards mental health interventions.</p> Methods <p>We developed a new scale—Beliefs about Biological Malleability (BBM) – to measure beliefs about the malleability of human biology and the extent to which biological malleability affects mental health. Undergraduates (<i>N</i> = 424) completed a survey with the BBM, reappraisal use and hypothetical mental health treatment preferences for traditional treatment (e.g., medication and psychotherapy) and lifestyle interventions (e.g., exercise and meditation).</p> Results <p>We found that the BBM separated into two factors: neurogenetics (e.g., perceived gene function and brain structure) and the peripheral body (e.g., heart rate and muscle size). The body was rated as more mutable than neurogenetics, whereas neurogenetics was rated as more likely to affect mental well-being than the body. Higher belief that biology is malleable related to greater reappraisal use. Greater belief that the body impacts mental-wellbeing related to preference for lifestyle interventions over traditional treatment, and preference for combining medication with psychotherapy over medication alone. Greater belief that neurogenetics affects mental well-being related to preference for combining traditional treatment with lifestyle interventions over traditional treatment alone.</p> Conclusions <p>Our results highlight the significance of essentialist and dualistic beliefs in students’ approaches to mental health care, and that universities may benefit from incorporating lifestyle interventions into treatment.</p>