Relation of BMI to a dual-energy X-ray absorptiometry measure of fatness

Dual-energy X-ray absorptiometry (DXA) is a valid technique for measuring the fat, bone and lean (muscle, organs and water) masses of the body. We evaluated relationships of BMI (kg/m2) with independent measurements of fat and lean masses using DXA in 226 adult volunteers. The evaluation was an application of a general approach to compositional data which has not previously been used for describing body composition. Using traditional regression analyses, when lean mass was held constant, BMI varied with fat mass (men r 0·75, P < 0·05 ; women r 0·85, P < 0·05); when fat mass was held constant, BMI varied with lean mass (men r 0·63, P < 0·05; women r 0·47, P < 0·05). In contrast, a regression model for compositional data revealed that BMI was: (a) strongly associated with log fat mass in both sexes (b1 4·86, P < 0·001 for all women and b1 5·96, P < 0·001 for all men); (b) not associated with bone mass, except in older men; (c) related to lean mass in women but not in men (b3 −4·04, P < 0·001 for all women and b1 −2·59, P < 0·15 for all men). Women with higher BMI tended to have more fat mass and more lean mass than women with lower BMI. Men with higher BMI had more fat mass but similar lean mass to men with lower BMI. Investigators need to be alert to the inaccuracy of BMI to assign a fatness risk factor to individuals, especially among wome

Contribution of body composition to nutritional assessment at hospital admission in 995 patients: a controlled population study

Body weight, weight changes and BMI are easily obtainable indicators of nutritional status, but they do not provide information on the amount of fat-free and fat masses. The purpose of the present study was to determine if fat-free mass (FFM) and fat mass were depleted in patients with normal BMI or serum albumin at hospital admission. A group of 995 consecutive patients were evaluated for malnutrition by BMI, serum albumin, and 50 kHz bioelectrical impedance analysis and compared with 995 healthy adults, matched for age and height, and then compared with FFM and fat mass percentiles previously determined in 5225 healthy adults. A BMI of ≤20 kg/m2 was noted in 17·3 % of patients and serum albumin of ≤35 g/l was found in 14·9 % of patients. In contrast, 31 % of all patients were below the tenth percentile for FFM, compared with 10·1 % of controls (χ2, P=0·0001), while 73 % of patients with BMI ≤20 kg/m2 and 31 % of patients with BMI 20-24·9 kg/m2 fell below the tenth percentile for FFM. Furthermore, the FFM was lower in patients than controls and the differences with age in FFM (lower) and fat mass (higher) were greater in patients than in controls. BMI and albumin significantly underestimated the prevalence of malnutrition in patients at hospital admission compared with body composition measurements. Optimal nutritional assessment should therefore include objective measurement of FFM and fat mas

Physical activity and fat-free and fat mass by bioelectrical impedance in 3853 adults

Effets de l'activité physique régulière sur la composition de la masse corporelle, mesurée par impédancemétrie bioélectrique, chez des sujets de 15 à 64 ans. Comparaison entre sujets sédentaires et actifs selon l'âge, effets du vieillissement

Prediction of outcome in head-and-neck cancer patients using the standardized uptake value of 2-[18F]fluoro-2-deoxy-D-glucose

Tumor uptake of 2-[(18)F] fluoro-2-deoxy-D-glucose (FDG) may relate to outcome in cancer patients. Pretreatment FDG uptake was evaluated as a predictor of local control (LC) and disease-free survival (DFS) in patients with head-and-neck cancer managed primarily either by radiotherapy (RT) or surgery