Sustainable lifestyle and nutrition in the adult population, including physically active people and athletes: the NUTRI_ACTIVE study

Lifestyle-related factors, particularly nutrition and physical activity, are central to health promotion and disease prevention throughout adulthood. Research has progressively shifted from a nutrient-based focus toward dietary patterns, with the Mediterranean Diet (MedDiet) recognized as a robust model for health and sustainability. Nonetheless, adherence to the MedDiet is declining, including among physically active individuals, and diet quality alone may not guarantee adequate fueling for sport. Inadequate dietary intake, limited nutrition knowledge, and maladaptive eating behaviors may predispose to suboptimal or low energy availability (EA) and related health consequences. Body composition, reflecting the interaction between diet, physical activity, and lifestyle, represents a key outcome with implications for both health and athletic performance. This PhD project aimed to advance understanding of how sustainable dietary patterns and informed nutritional behaviors support health, body composition, and performance in active populations. The project investigated dietary patterns, nutrition knowledge, and lifestyle factors in physically active adults and athletes, with four objectives: (i) to evaluate the association between MedDiet adherence and athletic performance via systematic review and meta-analysis; (ii) to assess the impact of nutritional counseling interventions in athletes through a systematic review; (iii) to examine MedDiet adherence, nutrition knowledge, lifestyle factors, dietary intake, EA, and body composition in physically active adults and athletes; and (iv) to explore sex-related differences in these domains in physically active Italian adults. Two systematic reviews were conducted following PRISMA guidelines. The first examined MedDiet adherence and performance in elite and competitive athletes training ≥6 h/week; the second evaluated nutritional counseling interventions in recreational and elite athletes. Risk of bias and methodological quality were assessed using validated tools. The observational component was the NUTRI_ACTIVE study, a single-centre cross-sectional study including 169 physically active adults and athletes (18-65 years). MedDiet adherence (MEDI-LITE), nutrition knowledge (GeSNK), eating behavior (EAT-26; TOS), physical activity (IPAQ), sleep quality (PSQI), dietary intake (7-day weighed food diary), anthropometry, body composition, resting energy expenditure (indirect calorimetry), and EA (sex-specific thresholds) were assessed. The first review included nine studies (192 athletes), mostly reporting positive associations with aerobic/anaerobic performance, strength, and body composition; however, meta-analysis showed no overall effect (SMD 0.00; 95% CI -0.26 to 0.25), likely due to heterogeneity and limited study quality. Nutritional counseling (10 studies) improved nutrition knowledge and dietary intake, with variable evidence for performance benefits. In the NUTRI_ACTIVE study, MedDiet adherence was moderate and higher in women. Nutrition knowledge was generally good, with women scoring higher in general nutrition. Mean energy intake was higher in men. Only 31.0% achieved optimal EA; 51.7% had suboptimal EA and 17.2% low EA, with pronounced sex differences: no women met optimal EA thresholds and 27.2% had low EA. Protein intake was generally adequate, while carbohydrate intake was often low. Expected sex-related differences in body composition were observed. Sustainable dietary patterns and nutrition knowledge are important but insufficient to ensure nutritional adequacy in physically active populations. Moderate MedDiet adherence may coexist with inadequate EA, particularly in women, underscoring the need for integrated, sport-specific and sex-sensitive nutritional strategies. Longitudinal and interventional studies are warranted to clarify causality and optimize health and performance in active individuals.