RCT Trajectory Mapper

Design: Parallel-group RCT (CONSORT)
Design classification. Parallel-group randomized controlled trial, 16 weeks, 1:1 allocation via computer-generated sequence with opaque sealed envelopes; CONSORT 2010 guidelines followed and a CONSORT diagram (Fig. 1) reported — meets Module E (RCT / CONSORT trajectory) criteria. Intervention group (IG, n=15) received individual dietary consultations at weeks 0/4/8 plus weekly remote support; control group (CG, n=15) received usual diet with basic advice only at study end. Per-protocol analysis on the 28 completers (14/arm) is the primary evidence base (Jayawardena et al., J Int Soc Sports Nutr 2026;23(1):2683613).
Enrolled n=30 → Randomized 1:1 IG baseline n=15week -2 3 consults wk 0,4,8+ weekly WhatsApp Lost to follow-up: 1completers n=14 Outcome wk16 (IG, n=14) TBF% (DEXA) 21.6→17.3, Δ-4.30±1.1, p=0.005 FFM (DEXA) 42.3→46.6 kg, Δ+4.28, p<0.001 HGS dominant 35.4→45.3 kg, p<0.001 divergence point → CG baseline n=15week -2 Usual diet, no advice3 "follow-up" visits only Lost to follow-up: 1completers n=14 Outcome wk16 (CG, n=14) TBF% 18.8→19.6, Δ+0.77±0.4, p=0.367 (ns) FFM 39.1→38.1 kg, Δ-1.08, p=0.051 (ns) HGS: no significant change Between-arm effect sizes at week 16 (IG vs CG) Fat mass % (BIA): between-group p<0.001, Cohen's d=0.64 — largest early divergence Fat-free mass (DEXA): between-group p<0.001, Cohen's d=0.68 Mid-upper arm circumference: IG Δ-3.48±1.0cm p<0.001 d=1.42 (largest single effect) Upper-arm fat area (UAFA): IG Δ-12.47cm² p<0.001 d=2.04 (very large effect) HGS dominant hand: IG Δ+9.92kg p<0.001 d=1.17 Outlier: FFM(BIA) fell in CG (-1.08kg) while rising in IG(+4.28kg) — opposite-direction divergence
Hub / textbook-path summary

The modal IG trajectory: baseline → 3 in-person consults (wk 0,4,8) + weekly WhatsApp support (wk 10-16) → reduced fat mass and increased fat-free mass and handgrip strength at week 16, all with p<0.05 and medium-large effect sizes (d=0.33-2.04). The modal CG trajectory: baseline → no structured advice → essentially flat or slightly worsening body composition (all CG changes non-significant, p>0.05). These are the two "textbook paths" a two-arm RCT naturally produces (Table 2, Jayawardena et al. 2026).

Outlier / divergence summary
NodeWhy notable
FFM (BIA) trajectory reversalIG gained FFM (+4.28kg) while CG lost FFM (-1.08kg) over the same 16 weeks — an opposite-direction split, the strongest signal in the whole dataset (between-group p<0.001), consistent with the paper's RED-S caution that unmonitored diets can erode lean mass (Discussion, refs [9,10,51]).
UAFA (upper-arm fat area)Largest effect size in the paper (d=2.04) — outlier-magnitude change relative to all other anthropometric nodes.
MUAC decreasing while FFM(DEXA) increasingApparent paradox (arm circumference shrank while whole-body FFM grew) — reflects fat loss from the upper arm outpacing lean gain there, a node worth flagging rather than averaging away.
References

Jayawardena R, Weerasinghe K, Nanayakkara I, Madhujith T, Hills AP, Kalupahana NS. Changes of body composition through an athlete-specific dietary guidance professional track and field athletes: a randomized controlled study. J Int Soc Sports Nutr. 2026;23(1):2683613. Trial registry: SLCTR/2024/013, UTN U1111-1304-8890.