Diet quality indices are a practical, cost-effective method to evaluate dietary patterns, yet few have investigated diet quality in athletes. This study describes the relative validity and reliability of the recently developed Athlete Diet Index (ADI). Participants completed the electronic ADI on two occasions, 2 weeks apart, followed by a 4-d estimated food record (4-dFR). Relative validity was evaluated by directly comparing mean scores of the two administrations (mAdm) against scores derived from 4-dFR using Spearman’s rank correlation coefficient and Bland–Altman (B–A) plots. Construct validity was investigated by comparing mAdm scores and 4-dFR-derived nutrient intakes using Spearman’s coefficient and independent t test. Test–retest reliability was assessed using paired t test, intraclass correlation coefficients (ICC) and B–A plots. Sixty-eight elite athletes (18·8 (sd 4·2) years) from an Australian sporting institute completed the ADI on both occasions. Mean score was 84·1 (sd 15·2; range 42·5–114·0). The ADI had good reliability (ICC = 0·80, 95 % CI 0·69, 0·87; P < 0·001), and B–A plots (mean 1·9; level of agreement −17·8, 21·7) showed no indication of systematic bias (y = 4·57–0·03 × x) (95 % CI −0·2, 0·1; P = 0·70). Relative validity was evaluated in fifty athletes who completed all study phases. Comparison of mAdm scores with 4-dFR-derived scores was moderate (rs 0·69; P < 0·001) with no systematic bias between methods of measurement (y = 6·90–0·04 × x) (95 % CI −0·3, 0·2; P = 0·73). Higher scores were associated with higher absolute nutrient intake consistent with a healthy dietary pattern. The ADI is a reliable tool with moderate validity, demonstrating its potential for application to investigate the diet quality of athletes.

Estimation of pre-pregnancy weight is difficult because measurements taken before pregnancy are rarely available. No studies have compared various ‘proxy’ measures using recalled weight or based on early pregnancy weight with actual measurements of pre-pregnancy weight. The Southampton Women’s Survey recruited women during 1998–2002 who were not pregnant. Data on 198 women with an estimated date of conception within 3 months of recruitment were analysed. Three proxy measures were considered: (1) recalled pre-pregnancy weight obtained during early pregnancy, (2) measured weight in early pregnancy and (3) estimated pre-pregnancy weight using a published model. Mean (standard deviation) recalled weight was 1.65 (3.03) kg lighter than measured pre-pregnancy weight, while early pregnancy weight and weights from the published model were 0.88 (2.34) and 0.88 (2.33) kg heavier, respectively. The Bland–Altman limits of agreement for recalled weight were −7.59 to 4.29 kg, wider than those for the early pregnancy weight: −3.71 to 5.47 kg and the published model: −3.68 to 5.45 kg. For estimating pre-pregnancy weight, we recommend subtraction of 0.88 kg from early pregnancy weight or the published model, or addition of 1.65 kg to recalled weight. Estimates of pre-pregnancy body mass index and gestational weight gain categories were very similar when using early pregnancy and published model weights, but they differed from those using recalled weight. Our findings indicate that calculations of first trimester weight gain using recalled weight must be treated cautiously, and a measured weight in early pregnancy provides a more precise assessment of pre-pregnancy weight than recalled weight.