The purpose of the present study was: (1) to develop a new dual-energy X-ray absorptiometry (DXA)-derived body volume (BV) equation with the GE-Lunar prodigy while utilising underwater weighing (UWW) as a criterion and (2) to cross-validate the novel DXA-derived BV equation (4C-DXANickerson), Wilson DXA-derived BV equation (4C-DXAWilson) and air displacement plethysmography (ADP)-derived BV (4C-ADP) in Hispanic adults. A total of 191 Hispanic adults (18–45 years) participated in the present study. The development sample consisted of 120 females and males (50 % females), whereas the cross-validation sample comprised of forty-one females and thirty males (n 71). Criterion body fat percentage (BF %) and fat-free mass (FFM) were determined using a four-compartment (4C) model with UWW as a criterion for BV (4C-UWW). 4C-DXANickerson, 4C-DXAWilson and 4C-ADP were compared against 4C-UWW in the cross-validation sample. 4C-DXANickerson, 4C-DXAWilson and 4C-ADP all produced similar validity statistics when compared with 4C-UWW in Hispanic males (all P > 0·05). 4C-DXANickerson also yielded similar BF % and FFM values as 4C-UWW when evaluating the mean differences (constant error (CE)) in Hispanic females (CE = –0·79 % and 0·38 kg; P = 0·060 and 0·174, respectively). However, 4C-DXAWilson produced significantly different BF % and FFM values (CE = 3·22 % and –2·20 kg, respectively; both P < 0·001). Additionally, 4C-DXAWilson yielded significant proportional bias when estimating BF % (P < 0·001), whereas 4C-ADP produced significant proportional bias for BF % and FFM (both P < 0·05) when evaluated in Hispanic females. The present study findings demonstrate that 4C-DXANickerson is a valid measure of BV in Hispanics and is recommended for use in clinics, where DXA is the main body composition assessment technique.

The reference organ-level body composition measurement method is MRI. Practical estimations of total adipose tissue mass (TATM), total adipose tissue fat mass (TATFM) and total body fat are valuable for epidemiology, but validated prediction equations based on MRI are not currently available. We aimed to derive and validate new anthropometric equations to estimate MRI-measured TATM/TATFM/total body fat and compare them with existing prediction equations using older methods. The derivation sample included 416 participants (222 women), aged between 18 and 88 years with BMI between 15·9 and 40·8 (kg/m2). The validation sample included 204 participants (110 women), aged between 18 and 86 years with BMI between 15·7 and 36·4 (kg/m2). Both samples included mixed ethnic/racial groups. All the participants underwent whole-body MRI to quantify TATM (dependent variable) and anthropometry (independent variables). Prediction equations developed using stepwise multiple regression were further investigated for agreement and bias before validation in separate data sets. Simplest equations with optimal R2 and Bland–Altman plots demonstrated good agreement without bias in the validation analyses: men: TATM (kg)=0·198 weight (kg)+0·478 waist (cm)−0·147 height (cm)−12·8 (validation: R2 0·79, CV=20 %, standard error of the estimate (SEE)=3·8 kg) and women: TATM (kg)=0·789 weight (kg)+0·0786 age (years)−0·342 height (cm)+24·5 (validation: R2 0·84, CV=13 %, SEE=3·0 kg). Published anthropometric prediction equations, based on MRI and computed tomographic scans, correlated strongly with MRI-measured TATM: (R2 0·70−0·82). Estimated TATFM correlated well with published prediction equations for total body fat based on underwater weighing (R2 0·70–0·80), with mean bias of 2·5–4·9 kg, correctable with log-transformation in most equations. In conclusion, new equations, using simple anthropometric measurements, estimated MRI-measured TATM with correlations and agreements suitable for use in groups and populations across a wide range of fatness.

We tested the validity and reliability of the BioSpace InBody 320, Omron and Bod-eComm body composition devices in men and women (n 254; 21–80 years) and boys and girls (n 117; 10–17 years). We analysed percentage body fat (%BF) and compared the results with dual-energy X-ray absorptiometry (DEXA) in adults and compared the results of the InBody with underwater weighing (UW) in children. All body composition devices were correlated (r 0·54–0·97; P ≤ 0·010) to DEXA except the Bod-eComm in women aged 71–80 years (r 0·54; P = 0·106). In girls, the InBody %BF was correlated with UW (r 0·79; P ≤ 0·010); however, a more moderate correlation (r 0·69; P ≤ 0·010) existed in boys. Bland–Altman plots indicated that all body composition devices underestimated %BF in adults (1·0–4·8 %) and overestimated %BF in children (0·3–2·3 %). Lastly, independent t tests revealed that the mean %BF assessed by the Bod-eComm in women (aged 51–60 and 71–80 years) and in the Omron (age 18–35 years) were significantly different compared with DEXA (P ≤ 0·010). In men, the Omron (aged 18–35 years), and the InBody (aged 36–50 years) were significantly different compared with DEXA (P = 0·025; P = 0·040 respectively). In addition, independent t tests indicated that the InBody mean %BF in girls aged 10–17 years was significantly different from UW (P = 0·001). Pearson's correlation analyses demonstrated that the Bod-eComm (men and women) and Omron (women) had significant mean differences compared with the reference criterion; therefore, the %BF output from these two devices should be interpreted with caution. The repeatability of each body composition device was supported by small CV ( < 3·0 %).

For the first time, body composition has been studied in a very large sample of female anorexia nervosa patients (n 200) using two methods: anthropometry (skinfold thickness) and densitometry (underwater weighing). The concurrent validity of both methods appeared to be good (r 0·84). Although the mean percentage of body fat (13·5) in our sample corresponds with most of the previous reports, the range (4·3–24·8) is great. Our study shows that BMI is not a good measure of fatness. Age and duration of illness were not related to body fat. Percentage fat was found to be different (t 2·76, P <0·01) according to the diagnostic subtype of anorexia nervosa: restricters (12·9) v. bingers and/or purgers (14·7).

The main purpose of the present study was to examine factors that affect bone mineral density (BMD) in female ballet dancers. Training history, Ca intake, body composition, total body BMD (TBMD) and site-specific BMD, and bone mineral content were described in twenty-four female ballet dancers (mean age 22·6 (SD 4·5) years). Training history was determined by questionnaires, Ca intake by 7 d dietary record, BMD and bone mineral content by dual-energy X-ray absorptiometry (DXA), total body water by 2H dilution, extracellular water by bromide dilution, body fat by underwater weighing (UWW; two-component model), DXA, and the four-component (4C) model. Dancers had a significantly lower body mass index (BMI 18·9 (SD 1·0) kg/m2) than controls (21·3 (SD 19) kg/m2), with significantly lower percentage body fat (17·4 (SD 3·9) v. 24·4 (SD 5·1)) but comparable fat-free mass. Mean TBMD (1·147 (SD 0 ·069) g/cm2) was significantly higher (6 %) compared with that of a reference population. These high values could be attributed to the high BMD of legs and pelvis, the weight-bearing sites of the dancer's body. No relationship was found between age, start of ballet classes, period (years) of dancing, Ca intake, and BMD (total and site-specific). However, TBMD was positively related to BMI, and negatively related to the age of menarche. BMD of the legs was significantly related to daily period (h) of training. Depending on the method used the percentage body fat ranged from 16·4 (by DXA) to 18·3 by the 4C model. These differences were significantly related to the TBMD. Percentage body fat by the different methods was not significantly different, except for DXA and 4C model. The present study showed that, despite the factors that have a negative effect on BMD, such as low body mass and late menarche, BMD in female ballet dancers was relatively high. These high values were probably caused by high levels of weight-bearing physical activity.

Deuterium dilution for the measurement of total body water (TBW) has been conducted using varying protocols for equilibration. We measured TBW from deuterium dilution in urine samples in twenty-eight subjects using three protocols: (1) early morning dosage without breakfast, measuring deuterium in a second voiding at 4h and 6h; (2) early morning dosage with breakfast with the same measurement times; (3) dosage as last consumption before overnight sleep, measuring deuterium in a second voiding at 10 h. Results were compared with TBW estimates from underwater weighing (UWW). Because UWW is an indirect measure of TBW, it is used as an independent reference method in order to compare only relative discrepancies between the two methods. TBW values in the fasted state were not significantly different from those obtained in the fed state. The urinary deuterium enrichment was higher at 4 h than at 6 h (resulting TBW differences: 0·6 (SD 0·4)I). At 4h and 6h, differences in TBW measurements from deuterium and densitometry were positively related to the amount of TBW, indicating incomplete equilibration in larger water compartments. At 10h no such relationship existed, indicating complete mixing of deuterium. It is concluded that 10h equilibration is preferable to the shorter 4h and 6h, for the determination of TBW.