Changes of body composition through an athlete-specific dietary guidance professional track and field athletes: a randomized controlled study

Background Optimal body composition (BC) is essential for athletic success, influencing performance outcomes. Athlete-specific nutrition interventions are important for improving BC and enhancing performance, but evidence is limited, especially in track and field athletes. This study aimed to assess the effect of athlete-specific dietary guidance on BC in Sri Lankan track and field athletes.Methods A 16-week trial was conducted with 30 athletes, 15 in each group: intervention (IG) and control (CG). The IG received athlete-specific dietary guidance through individual consultations at weeks 0, 4, and 8, along with weekly nutrition advice. BC was assessed using anthropometry, bioelectrical impedance analysis (BIA), and dual-energy X-ray absorptiometry (DEXA). Muscle strength, as a component of physical fitness, was assessed via handgrip strength (HGS).Results Fourteen participants from each group completed the study. The IG demonstrated a significant decrease in fat mass percentage (FM) derived from BIA (Pre: 21.80 ± 7.0% vs. Post: 17.25 ± 5.8%; Change: −4.55 ± 1.2%; p = 0.003), while the CG demonstrated a no significant change (Pre: 18.87 ± 7.84% vs. Post: 19.60 ± 5.84%; Change: + 0.73 ± 3.0%; p = 0.475). The body fat percentage derived from DEXA also demonstrated significant reductions in the IG (Pre: 21.60 ± 7.1% vs. Post: 17.30 ± 6.0%; Change: −4.30 ± 1.1%; p = 0.005), and the CG exhibited a no significant change (Pre: 18.84 ± 3.9% vs. Post: 19.61 ± 6.5%; Change: + 0.77 ± 0.4%; p = 0.367). Fat-free mass (FFM) derived from DEXA increased in IG (Pre: 42.29 ± 6.0 kg vs. Post: 46.57 ± 6.4 kg; Change: +4.28 ± 0.4 kg; p < 0.001) when compared to CG (Pre: 39.13 ± 11.4 kg vs. Post: 38.05 ± 11.7 kg; Change: −1.08 ± 0.3 kg; p = 0.051). The IG showed significantly better HGS.Conclusions Athlete-specific dietary guidance significantly improved BC and physical fitness among track and field athletes.Trial registration This trial was registered in the Sri Lanka Clinical Trials Registry (SLCTR/2024/013) under Universal Trial Number (UTN) U1111-1304-8890 on 10 April 2024.