Relationships of motivation, self-efficacy and social support with healthy eating behaviours among adolescents

Purpose Psychosocial factors contributing to the continued failure of adolescents to follow the US Dietary Guidelines for Americans (2020–2025 ) remain poorly understood. This study investigated the relationships of adolescents’ autonomous motivation, self-efficacy and social support with the healthy eating index (HEI) total (primary outcome), whole fruit, total fruit, vegetable, sodium, added sugar and caloric intake (secondary outcomes). Methods A secondary analysis of baseline data from a randomised controlled trial was conducted. A total of 935 5th–8th graders, aged 10–14 years, were enrolled. Generalised linear models and structural equation models examined relationships of motivation, social support and self-efficacy for healthy eating with healthy eating behaviours. Results In this sample (51% female, mean age=12.08±0.99), 48.24% were black/African American, and 48.2% were overweight/obese. In generalised linear models, family social support was significantly associated with HEI fruit (β=0.16, p=0.02) and higher caloric intake (β=44.09, p=0.03). Additionally, friend social support was significantly associated with HEI sodium (lower sodium intake; β=0.23, p=0.01). Structural equation models showed that through motivation, social support indirectly improved HEI total (β=0.09, p=0.006) and whole fruit intake (β=0.07, p=0.04) and increased HEI added sugar (lower added sugar intake; β=0.07, p=0.04). Through self-efficacy, social support was indirectly associated with lower HEI sodium (higher sodium intake; β=–0.04, p=0.04). Discussion These findings add to the growing body of research on adolescent nutrition by emphasising the complex interplay of psychosocial factors in shaping specific dietary behaviours. Trial registration number NCT04213014 .