Introduction and objective:
Well-being in physically active adults is shaped by multiple interacting lifestyle factors. The aim of the study is to examine associations between nutrient density, energy availability (EA), and stress levels with well-being in adults meeting the World Health Organisation (WHO) physical activity guidelines.

Material and methods:
The cross-sectional study included 312 female 115 male amateur athletes (18–40 years old; mean age ± SD: 29.8 ± 5.7 for women and 31.2 ± 5.7 for men) who reported engaging in ≥75 minutes of vigorous-intensity aerobic activity per week. Food intake was assessed using a validated 138-item food frequency questionnaire; stress level was measured using a Visual Analogue Scale (VAS), and well-being measured using the WHO-5 Well-Being Index (WHO-5- Index). EA was calculated as dietary energy intake minus exercise energy expenditure, normalised to body mass. To identify predictors of well-being, multivariate-adjusted logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (95% CIs).

Results:
Overall, 36.2% of women and 29.6% of men were classified as having poor well-being (WHO-5-Index <13). In multivariable models, lower perceived stress was independently associated with better well-being (OR=0.62 per 1-point increase on the VAS; 95% CI: 0.54–0.70; P-trend <0.001). Additionally, higher dietary densities of vitamin A, folate, vitamin B12, potassium, iron and copper, were significantly associated with better well-being (all P-trends ≤0.05). No such associations were observed for EA.

Conclusions:
These findings indicate that lower perceived stress and higher dietary nutrient density are independently associated with better well-being in physically active adults.