Abstract Body: Background
Self-reported, free-living energy intake (rEI) by dietary recalls are notoriously inaccurate. Assessment of rEI plausibility have been limited to arbitrary assumptions or validation against measured energy expenditure (mEE) by doubly-labeled water (DLW). We aimed to identify plausible dietary recalls using an updated formula that considers measured energy intake calculated by DLW (mEI) instead.

Methods
In a two-week cross-sectional study, up to six rEI by repeated Automated Self-Administered 24-Hour (ASA24®) Dietary Assessment Tool, with body energy store changes (ΔBES) measured by quantitative magnetic resonance (QMR) on days 1 and 14, mEE assessed by DLW, and mEI computed by energy balance equation (mEE + ΔBES). Participants were asked to maintain an eucaloric diet. A rEI:mEI ratio was calculated for each participant, and a group cut-off was calculated using the formula: ±1SD = √(CVrEI²)/d)+(CVmEI²). Dietary recall entries within ±1SD of the cutoffs were categorized as plausible (PR), <1SD categorized as under-reported (UR), >1SD categorized as over-reported (OR). Spearman correlations and linear regression performed to evaluate the linear relationships for continuous variables. Results are mean±SD. Significance set at p<0.05.

Results
In our cohort (n=39, age: 60.6±6.9 years, BMI: 33.1±6.4 kg/m², 33.3% men), 50%, 26.3%, 23.7% of the dietary recalls were UR, PR and OR, respectively. The rEI:mEI ratio showed a significant negative correlation with body weight (ß=-0.38, p =0.02). Greater mEI predicted higher body weight (ß=26.6, p<0.01) and BMI (ß=51.4, p=0.02). In contrast, no relationships were observed between rEI and body weight (ß=9.3, p=0.09) or BMI (ß=22.5, p=0.28). However, in PR entries alone, rEI predicted greater body weight (ß=19.5, p<0.01) and BMI (ß=44.8, p=0.04).

Conclusion
These preliminary results align with past studies supporting higher implausible energy intake in adults with greater body weight, based on self-reported dietary recalls. In contrast to rEI, we found a consistent and significant association between mEI and PR, with body weight and BMI. This supports the notion that higher energy requirements are needed to maintain energy balance in individuals with greater body mass. These findings support this method for identifying plausible reporting (PR) when assessing dietary intake.