Associations of early childhood body mass index trajectories with body composition and cardiometabolic markers at age 10 years: the Ethiopian infant anthropometry and body composition (iABC) birth cohort study.

BACKGROUND: Variability in body mass index (BMI) (kg/m2) trajectories is associated with body composition and cardiometabolic markers in early childhood, but it is unknown how these associations track to later childhood. OBJECTIVES: We aimed to assess associations of BMI trajectories from 0 to 5 y with body composition and cardiometabolic markers at 10 y. METHODS: In the Ethiopian infant anthropometry and body composition (iABC) birth cohort, we previously identified 4 distinct BMI trajectories from 0 to 5 y: stable low BMI (19.2%), normal BMI (48.8%), rapid growth to high BMI (17.9%), and slow growth to high BMI (14.1%). At 10 y, we obtained data from 320 children on anthropometry, body composition, abdominal subcutaneous and visceral fat, and cardiometabolic markers. Associations of BMI trajectories and 10-y outcomes were analyzed using multiple linear regression. RESULTS: Compared with children with the normal BMI trajectory, those with rapid growth to high BMI had 1.7 cm (95% CI: 0.1, 3.3) larger waist circumference and those with slow growth to high had 0.63 kg/m2 (95% CI: 0.09, 1.17) greater fat mass index and 0.19 cm (95% CI: 0.02, 0.37) greater abdominal subcutaneous fat, whereas those with stable low BMI had -0.28 kg/m2 (95% CI: -0.59, 0.03) lower fat-free mass at 10 y. Although the confidence bands were wide and included the null value, children with rapid growth to high BMI trajectory had 48.6% (95% CI: -1.4, 123.8) higher C-peptide concentration and those with slow growth to high BMI had 29.8% (95% CI: -0.8, 69.8) higher insulin and 30.3% (95% CI: -1.1, 71.6) higher homeostasis model assessment of insulin resistance, whereas those with rapid growth to high BMI had -0.23 mmol/L (95% CI: -0.47, 0.02) lower total cholesterol concentration. The trajectories were not associated with abdominal visceral fat, blood pressure, glucose, and other lipids at 10 y. CONCLUSIONS: Children with rapid and slow growth to high BMI trajectories before 5 y tend to show higher measures of adiposity and higher concentrations of markers related to glucose metabolism at 10 y. CLINICAL TRIAL REGISTRY: ISRCTN46718296 (https://www.isrctn.com/ISRCTN46718296).

Associations of weight and body composition at birth with body composition and cardiometabolic markers in children aged 10 y: the Ethiopian infant anthropometry and body composition birth cohort study.

BACKGROUND: Although birth weight (BW) has been associated with later cardiovascular disease and type 2 diabetes, the role of birth fat mass (BFM) and birth fat-free mass (BFFM) on cardiometabolic health is unclear. OBJECTIVES: To examine associations of BW, BFM, and BFFM with later anthropometry, body composition, abdominal fat, and cardiometabolic markers. METHODS: Birth cohort data on standardized exposure variables (BW, BFM, and BFFM) and follow-up information at age 10 y on anthropometry, body composition, abdominal fat, and cardiometabolic markers were included. A linear regression analysis was used to assess associations of exposures with outcome variables, adjusting for maternal and child characteristics at birth and current body size in separate models. RESULTS: Among 353 children, mean (SD) age was 9.8 (1.0) y, and 51.5% were boys. In the fully adjusted model, 1-SD higher BW and BFFM were associated with 0.81 cm (95% CI: 0.21, 1.41 cm) and 1.25 cm (95% CI: 0.64, 1.85 cm) greater height at 10 y, respectively. The 1-SD higher BW and BFM were associated with 0.32 kg/m2 (95% CI: 0.14, 0.51 kg/m2) and 0.42 kg/m2 (95% CI: 0.25, 0.59 kg/m2) greater fat mass index at 10 y, respectively. In addition, 1-SD higher BW and BFFM were associated with 0.22 kg/m2 (95% CI: 0.09, 0.34 kg/m2) greater FFM index, whereas a 1-SD greater BFM was associated with a 0.05 cm greater subcutaneous adipose tissue (95% CI: 0.01, 0.11 cm). Furthermore, 1-SD higher BW and BFFM were associated with 10.3% (95% CI: 1.4%, 20.0%) and 8.3% (95% CI: -0.5%, 17.9%) greater insulin, respectively. Similarly, 1-SD higher BW and BFFM were associated with 10.0% (95% CI: 0.9%, 20.0%) and 8.5% (95% CI: -0.6%, 18.5%) greater homeostasis model assessment of insulin resistance, respectively. CONCLUSIONS: BW and BFFM rather than BFM are predictors of height and FFM index at 10 y. Children with higher BW and BFFM showed higher insulin concentrations and homeostasis model assessment of insulin resistance at 10 y of age. This trial was registered at ISRCTN as ISRCTN46718296.

Metabolizable Energy Content of Breastmilk Supports Normal Growth in Exclusively Breastfed Icelandic Infants to Age 6 Months.

BACKGROUND: Neither the global population nor individual countries have reached the World Health Organization (WHO) target of ≥50% of infants exclusively breastfed (EBF) until 6 mo. This may partly be because of the perceptions of insufficient milk and energy supply to meet rapid growth and development needs. OBJECTIVES: In a longitudinal observational study, we aimed to determine whether breastmilk energy content is sufficient to support growth during EBF until 6 mo. METHODS: A sample of 27 EBF infants was dosed with doubly labeled water (DLW) at 5.6 mo to measure body composition, breastmilk intake, energy intake, and the metabolizable energy (ME) content of their mother's breastmilk over the following week. Z-scores were calculated for anthropometry using WHO reference data and for fat-free mass (FFM) and fat mass (FM) using United Kingdom reference data. RESULTS: Anthropometric z-scores from birth indicated normal weight and length growth patterns. At ∼6 mo, the mean ± standard deviation (SD) FFM z-score was 0.22 ± 1.07, and the FM z-score was 0.78 ± 0.70, significantly >0. In the 22 infants with acceptable data, the mean ± SD measured intake of breastmilk was 983 ± 170 g/d and of energy, 318 ± 60 kJ/kg/d, equivalent to 75.9 ± 14.3 kcal/kg/d. The mean ME content of breastmilk was 2.61 kJ/g [standard error (SE) 0.1], equivalent to 0.62 kcal/g (SE 0.02). Mothers were positive toward breastfeeding, on paid maternity leave (planned mean 10 mo), and many (56%) had received specialized breastfeeding support. CONCLUSIONS: The evidence from this study confirms that when mothers are motivated and supported without economic restraints, breastmilk intake and the energy supplied by breastmilk to EBF infants at 6 mo of age is sufficient to support normal growth patterns. There was no evidence of constraint on FFM, and other studies show that high FM in EBF infants is likely to be transient. These data further support the recommendation for EBF ≤6 mo of age for body composition. This trial was registered at clinicaltrials.gov as NCT02586571.

Post-malnutrition growth and its associations with child survival and non-communicable disease risk: a secondary analysis of the Malawi 'ChroSAM' cohort.

OBJECTIVE: To explore patterns of post-malnutrition growth (PMGr) during and after treatment for severe malnutrition and describe associations with survival and non-communicable disease (NCD) risk 7 years post-treatment. DESIGN: Six indicators of PMGr were derived based on a variety of timepoints, weight, weight-for-age z-score and height-for-age z-score (HAZ). Three categorisation methods included no categorisation, quintiles and latent class analysis (LCA). Associations with mortality risk and seven NCD indicators were analysed. SETTING: Secondary data from Blantyre, Malawi between 2006 and 2014. PARTICIPANTS: A cohort of 1024 children treated for severe malnutrition (weight-for-length z-score < 70 % median and/or MUAC (mid-upper arm circumference) < 110 mm and/or bilateral oedema) at ages 5-168 months. RESULTS: Faster weight gain during treatment (g/d) and after treatment (g/kg/day) was associated with lower risk of death (adjusted OR 0·99, 95 % CI 0·99, 1·00; and adjusted OR 0·91, 95 % CI 0·87, 0·94, respectively). In survivors (mean age 9 years), it was associated with greater hand grip strength (0·02, 95 % CI 0·00, 0·03) and larger HAZ (6·62, 95 % CI 1·31, 11·9), both indicators of better health. However, faster weight gain was also associated with increased waist:hip ratio (0·02, 95 % CI 0·01, 0·03), an indicator of later-life NCD risk. The clearest patterns of association were seen when defining PMGr based on weight gain in g/d during treatment and using the LCA method to describe growth patterns. Weight deficit at admission was a major confounder. CONCLUSIONS: A complex pattern of benefits and risks is associated with faster PMGr. Both initial weight deficit and rate of weight gain have important implications for future health.

Effects of relaxation therapy on maternal psychological status and infant growth following late preterm and early-term delivery: a randomized controlled trial.

BACKGROUND: Maternal stress is one modifiable variable that could influence mother-infant signaling and negatively affect breastfeeding and infant growth. OBJECTIVES: This study aimed to test the hypothesis that relaxation therapy would reduce maternal stress and improve infant growth, behavior, and breastfeeding outcomes after late preterm (LP) and early-term (ET) delivery. METHODS: A single-blind randomized controlled trial was conducted in healthy Chinese primiparous mother-infant pairs after LP or ET delivery (34+0-37+6 gestation weeks). Mothers were randomly assigned to the intervention group (IG, listening to relaxation meditation at least once a day) or control group (CG, normal care). Primary outcomes-changes in maternal stress (perceived stress scale), anxiety (Beck Anxiety Inventory), and infant weight and length standard deviation score-were assessed at 1 wk and 8 wks postpartum. Secondary outcomes-breast milk energy and macronutrient composition, maternal breastfeeding attitudes, infant behaviors (3-d diary), and 24-hour milk intake-were assessed at 8 wks. RESULTS: In total, 96 mother-infant pairs were recruited. There was a significantly greater reduction in maternal perceived stress (Perceived Stress Scale score) (mean difference [MD] = 2.65; 95% CI: 0.8, 4.5) and significantly greater infant weight standard deviation score gain (MD = 0.51; 95% CI: 0.2, 0.9) from 1 wk to 8 wks in the IG than those in the CG. Exploratory analyses showed a significant interaction between intervention and sex, with greater effects on weight gain in female infants. Mothers of female infants used the intervention more frequently with significantly higher milk energy observed at 8 wks. CONCLUSIONS: The relaxation meditation tape is a simple, effective practical tool that could easily be used in clinical settings to support breastfeeding mothers after LP and ET delivery. The findings need confirmation in larger groups and in other populations.

Childhood BMI and other measures of body composition as a predictor of cardiometabolic non-communicable diseases in adulthood: a systematic review.

OBJECTIVE: There is growing evidence that childhood malnutrition is associated with non-communicable diseases (NCD) in adulthood and that body composition mediates some of this association. This review aims to determine if childhood body composition can be used to predict later-life cardiometabolic NCD and which measures of body composition predicts future NCD. DESIGN: Electronic databases were searched for articles where: children aged under 5 years had body composition measured; cardiometabolic health outcomes were measured a minimum of 10 years later. SETTING: The databases Embase, Medline and Global Health were searched through July 2020. PARTICIPANTS: Children aged under 5 years with a follow-up of minimum 10 years. RESULTS: Twenty-nine studies met the inclusion criteria. Though a poor proxy measure of body composition, body mass index (BMI) was commonly reported (n 28, 97 %). 25 % of these studies included an additional measure (ponderal index or skinfold thickness). Few studies adjusted for current body size (n 11, 39 %). CONCLUSIONS: Many studies reported that low infant BMI and high childhood BMI were associated with an increased risk of NCD-related outcomes in later life but no conclusions can be made about the exact timing of child malnutrition and consequent impact on NCD. Because studies focussed on BMI rather than direct measures of body composition, nothing can be said about which measures of body composition in childhood are most useful. Future research on child nutrition and long-term outcomes is urgently needed and should include validated body composition assessments as well as standard anthropometric and BMI measurements.

Comprehensive analysis of the association of seasonal variability with maternal and neonatal nutrition in lowland Nepal.

OBJECTIVE: To provide a comprehensive seasonal analysis of pregnant mothers' eating behaviour and maternal/newborn nutritional status in an undernourished population from lowland rural Nepal, where weather patterns, agricultural labour, food availability and disease prevalence vary seasonally. DESIGN: Secondary analysis of cluster-randomised Low Birth Weight South Asia Trial data, applying cosinor analysis to predict seasonal patterns. OUTCOMES: Maternal mid-upper arm circumference (MUAC), BMI, dietary diversity, meals per day, eating down and food aversion in pregnancy (≥31 weeks' gestation) and neonatal z-scores of length-for-age (LAZ), weight-for-age (WAZ) and head circumference-for-age (HCAZ) and weight-for-length (WLZ). SETTING: Rural areas of Dhanusha and Mahottari districts in plains of Nepal. PARTICIPANTS: 2831 mothers aged 13-50 and 3330 neonates. RESULTS: We found seasonal patterns in newborn anthropometry and pregnant mothers' anthropometry, meal frequency, dietary diversity, food aversion and eating down. Seasonality in intake varied by food group. Offspring anthropometry broadly tracked mothers'. Annual amplitudes in mothers' MUAC and BMI were 0·27 kg/m2 and 0·22 cm, with peaks post-harvest and nadirs in October when food insecurity peaked. Annual LAZ, WAZ and WLZ amplitudes were 0·125, 0·159 and 0·411 z-scores, respectively. Neonates were the shortest but least thin (higher WLZ) in winter (December/January). In the hot season, WLZ was the lowest (May/June) while LAZ was the highest (March and August). HCAZ did not vary significantly. Food aversion and eating down peaked pre-monsoon (April/May). CONCLUSIONS: Our analyses revealed complex seasonal patterns in maternal nutrition and neonatal size. Seasonality should be accounted for when designing and evaluating public heath nutrition interventions.

Validation of bioelectrical impedance analysis for body composition assessment in children with obesity aged 8-14y.

BACKGROUND & AIMS: The aim was to generate a predictive equation to assess body composition (BC) in children with obesity using bioimpedance (BIA), and avoid bias produced by different density levels of fat free mass (FFM) in this population. METHODS: This was a cross-sectional validation study using baseline data from a randomized intervention trial to treat childhood obesity. Participants were 8 to 14y (n = 315), underwent assessments on anthropometry and BC through Air Displacement Plethysmography (ADP), Dual X-Ray Absorptiometry and BIA. They were divided into a training (n = 249) and a testing subset (n = 66). In addition, the testing subset underwent a total body water assessment using deuterium dilution, and thus obtained results for the 4-compartment model (4C). A new equation to estimate FFM was created from the BIA outputs by comparison to a validated model of ADP adjusted by FFM density in the training subset. The equation was validated against 4C in the testing subset. As reference, the outputs from the BIA device were also compared to 4C. RESULTS: The predictive equation reduced the bias from the BIA outputs from 14.1% (95%CI: 12.7, 15.4) to 4.6% (95%CI: 3.8, 5.4) for FFM and from 18.4% (95%CI: 16.9, 19.9) to 6.4% (95% CI: 5.3, 7.4) for FM. Bland-Altman plots revealed that the new equation significantly improved the agreement with 4C; furthermore, the observed trend to increase the degree of bias with increasing FM and FFM also disappeared. CONCLUSION: The new predictive equation increases the precision of BC assessment using BIA in children with obesity.

Utility of bio-electrical impedance vector analysis for monitoring treatment of severe acute malnutrition in children.

BACKGROUND & AIMS: Change in hydration is common in children with severe acute malnutrition (SAM) including during treatment, but is difficult to assess. We investigated the utility of bio-electrical impedance vector analysis (BIVA), a quick non-invasive method, for indexing hydration during treatment. METHODS: We studied 350 children 0·5-14 years of age with SAM (mid-upper arm circumference <11·0 cm or weight-for-height <70% of median, and/or nutritional oedema) admitted to a hospital nutrition unit, but excluded medically unstable patients. Weight, height (H), resistance (R), reactance (Xc) and phase angle (PA) were measured and oedema assessed. Similar data were collected from 120 healthy infants and preschool/school children for comparison. Means of height-adjusted vectors (R/H, Xc/H) from SAM children were interpreted using tolerance and confidence ellipses of corresponding parameters from the healthy children. RESULTS: SAM children with oedema were less wasted than those without (p < 0·001), but had BIVA parameters that differed more from those of healthy children (P < 0·05) than those non-oedematous. Initially, both oedematous and non-oedematous SAM children had mean vectors outside the reference 95% tolerance ellipse. During treatment, mean vectors migrated differently in the two SAM groups, indicating fluid loss in oedematous patients, and tissue accretion in non-oedematous patients. At admission, R/H was lower (oedematous) or higher (non-oedematous) among children who died than those who exited the hospital alive. CONCLUSIONS: BIVA can be used in children with SAM to distinguish tissue-vs. hydration-related weight changes during treatment, and also identify children at high risk of death enabling early clinical interventions.

Utility of specific bioelectrical impedance vector analysis for the assessment of body composition in children.

BACKGROUND & AIMS: Bioelectrical impedance analysis (BIA) is widely considered a body composition technique suitable for routine application. However, its utility in sick or malnourished children is complicated by variability in hydration. A BIA variant termed vector analysis (BIVA) aims to resolve this, by differentiating hydration from cell mass. However, the model was only partially supported by children's data. To improve accuracy, further adjustment for body shape variability has been proposed, known as specific BIVA (BIVAspecific). METHODS: We re-analysed body composition data from 281 children and adolescents (46% male) aged 4-20 years of European ancestry. Measurements included anthropometry, conventional BIA, BIVA outcomes adjusted either for height (BIVAconventional), or for height and body cross-sectional area (BIVAspecific), and fat-free mass (FFM) and fat mass (FM) by the criterion 4-component model. Graphic analysis and regression analysis were used to evaluate different BIA models for predicting FFM and FM. RESULTS: Age was strongly correlated with BIVAconventional parameters, but weakly with BIVAspecific parameters. FFM correlated more strongly with BIVAconventional than with BIVAspecific parameters, whereas the opposite pattern was found for FM. In multiple regression analyses, the best prediction models combined conventional BIA with BIVAspecific parameters, explaining 97.0% and 89.8% of the variance in FFM and FM respectively. These models could be further improved by incorporating body weight. CONCLUSIONS: The prediction of body composition can be improved by combining two different theoretical models, each of which appears to provide different information about the two components FFM and FM. Further work should test the utility of this approach in pediatric patients.

Filling the weight gap: Estimating body weight and BMI using height, chest and upper arm circumference of Swiss conscripts in the first half of the 20th century.

We estimate weight and BMI values based on height, chest circumference, and mid upper arm circumference measures of Swiss conscripts in the city of Zurich for each year between 1904 and 1932. Height, chest circumference, and mid upper arm circumference were measured each year from 1904 to 1951. Body weight is available from 1933 to 1951. We used prediction equations from the literature, and also developed our own equations, which we tested and validated on the dataset from 1933 to 1951. We used a representative sample of usually 19-year-old Swiss males (N = 88,792, coverage > 88 %). There was an increase in average height and chest circumference between 1904 and 1951. During both world wars, chest circumference, mid upper arm circumference, weight, and BMI decreased, while height stagnated. Overall mean weight and BMI increased from 1904 to 1951, but decreased during the Great Depression. After World War II, weight quickly returned to the pre-war and pre-Great Depression level, while BMI had not reached the 1933 level by 1951. Average weights of the lower and middle socioeconomic groups were catching up with average weight of the upper socioeconomic group from 1904 to 1951. The convergence in height is less pronounced. Finally, we show that it is possible to accurately predict mean weight and BMI from other anthropometric measurements. We suggest that our estimation approach could be replicated for other historical populations to obtain more information on how nutritional status changed over time.

Obesity is not just elevated adiposity, it is also a state of metabolic perturbation.

Nettle et al. miss the crucial difference between adaptive models of storing energy and explanations for the pathological metabolic state of obesity. I suggest that the association of food insecurity with obesity in women from industrialized settings is most likely due to reverse causation: Poverty reduces agency to resist obesogenic foods, and this scenario is compounded by perturbations of insulin metabolism stemming from high adiposity and lipogenic diets.

Weight centile crossing in infancy: correlations between successive months show evidence of growth feedback and an infant-child growth transition.

BACKGROUND: Early rapid weight gain is associated with later overweight, which implies that weight centile crossing tracks over time. OBJECTIVE: Centile crossing is defined in terms of the change or deviation in weight z score during 1 mo, and the correlations between successive deviations are explored at different ages. DESIGN: Two Cambridge (United Kingdom) growth cohorts were used: Widdowson (1094 infants born during 1959-1965) and the Cambridge Infant Growth Study (CIGS; 255 infants born during 1984-1987), each with weights measured monthly in the first year. Weights were converted to WHO age- and sex-adjusted z scores, deviations were calculated as the change in z score between adjacent measurement occasions, and the correlations between deviations were studied. RESULTS: In both cohorts, the correlations between successive monthly deviations were positive in the first 6 mo and highest at ages 3-4 mo (r = 0.3, P < 0.0001), whereas after 6 mo they were negative and were lowest at ages 10-11 mo (r = -0.3, P < 0.0001), with the correlation decreasing linearly with age between these extremes. Thus, during the first 6 mo of age, infants crossing centiles in 1 mo tended to continue crossing centiles in the same direction the following month, whereas after 6 mo they tended to cross back again. This represents positive and negative feedback, respectively. At age 12 mo, the correlation was close to zero, which suggests an infant-child transition in growth. CONCLUSIONS: The results confirm that weight centile crossing tracks over time, with the correlations between successive periods that change with age suggesting a complex feedback mechanism underlying infant growth. This may throw light on the link between early rapid weight gain and later overweight. Clinically, the correlations indicate that when predicting future weight from current weight, recent centile crossing affects the prediction in an age-dependent manner.

Objectively measured physical activity and body composition indices in Brazilian adolescents / Atividade física mensurada objetivamente e índices de composição corporal em adolescentes Brasileiros

The aim of the study was to explore the association between objectively measured physical activity and body composition indices in 13-year old adolescents living in country undergoing rapid nutritional transition. A population-based cross-sectional study nested within the 1993 Pelotas (Brazil) Birth Cohort was undertaken. A total of 457 boys and girls (80.5% of the target sample, 52.1% boys) participated in the study. Physical activity was measured by the Actigraph accelerometer for 5 consecutive days and expressed as total physical activity (i.e. average intensity, counts per minute) and time (min per day) spent at moderate and vigorous intensity activity. The outcomes investigated were sum of triceps and subscapular skinfolds, waist circumference, waist-to-hip ratio and waist-to-thigh ratio. After adjustment for sex, socioeconomic status, age, Tanner stage of sexual maturation, diet pattern, height, and birth weight, time (min/day) spent at vigorous intensity activity was inversely associated with waist circumference and sum of skinfolds. A one minute/day increase in vigorous intensity physical activity was associated, on average, with a reduction of 0.15cm in waist circumference (p=0.007) and 0.20mm in sum of skinfold thicknesses (p=0.02). These associations were stronger in boys than in girls. Total activity and time spent in moderate intensity physical activities were not associated with any of the outcomes in the adjusted analyses. Vigorous physical activity appears to have the strongest association with body composition. Preventive efforts aimed to decrease the obesity in adolescents may be more successful if they focus on vigorous intensity, instead of moderate intensity physical activities.

O objetivo deste estudo foi explorar a associação entre atividade física mensurada objetivamente e índices de composição corporal em adolescentes de 13 anos de idade residentes em um país sofrendo rápida transição nutricional. Um estudo transversal de base populacional aninhado a Coorte de Nascimentos de 1993 de Pelotas (Brasil) foi realizado. Um total de 457 meninos e meninas (80,5% da população alvo; 52,1% meninos) participaram do estudo. Atividade física foi mensurada pelo acelerômetro Actigraph por 5 dias consecutivos e expressa como atividade física total (intensidade média, counts por minuto) e tempo (min/dia) em atividades moderadas e vigorosas. Os desfechos investigados foram somatório de dobras triciptal e subescapular, circunferência da cintura, razão cintura-quadril e razão cintura-coxa. Após ajustes para sexo, nível econômico, idade, estágio de maturação sexual de Tanner, padrão de dieta, estatura e peso ao nascer, o tempo (min/dia) em atividades vigorosas foi inversamente associado à circunferência da cintura e somatório das dobras. O aumento de um minuto por dia no tempo em atividades vigorosas foi associado, em média, com uma redução de 0,15cm na circunferência da cintura (p=0,007) e 0,20mm no somatório das dobras (p=0,02). Estas associações foram mais fortes nos meninos comparado as meninas. Atividade física total e tempo em atividades moderadas não foram associados com nenhum dos desfechos na análise ajustada. Atividades vigorosas parecem ter a associação mais forte com composição corporal. Esforços preventivos que visem diminuir a obesidade em adolescentes podem ter mais sucesso se focarem em atividades vigorosas ao invés de atividades de intensidade moderada.

Body composition assessed by the 4-component model and association with lung function in 6-12-y-old children with cystic fibrosis.

BACKGROUND: Malnutrition is an indicator of a poor prognosis in patients with cystic fibrosis (CF). Previous body-composition (BC) studies in children with CF used 2-component models (2CMs) to assess fat mass (FM) and fat-free mass (FFM), but to our knowledge no study has used the gold-standard 4-component model (4CM), which allows for a more accurate evaluation of the nature of both elements. OBJECTIVE: We measured BC by using the 4CM in 6-12-y-old children with CF to 1) compare findings with those of healthy, matched control children and reference data; 2) relate BC to lung spirometry [forced expired volume in 1 s (FEV1)]; and 3) compare findings with those from more commonly used 2CM techniques. DESIGN: One hundred clinically stable children with CF (57% girls) aged 6-12 y were measured by using the 4CM. Children with CF underwent spirometry (FEV1). RESULTS: Girls with CF had significantly less FM than did healthy girls, even after adjustment for height and pubertal status; boys with CF had higher body mass index SD scores than did healthy boys. FM in girls was positively associated with the FEV1 percentage predicted. The 2CM FM was significantly different from the 4CM FM, with differences dependent on sex and condition, although most techniques identified a relation between FM and FEV1 in girls. CONCLUSIONS: Although shorter than healthy children, boys with CF were heavier and had a BC within the normal range; however, girls with CF had lower FM than did healthy girls, and this was associated with poorer lung function. Given the worse prognosis in girls, this finding merits more attention. The reliability of 2CM techniques varied with sex and health status.

Infant growth and later body composition: evidence from the 4-component model.

BACKGROUND: Rapid weight gain in infancy is associated with higher body mass index in later life, but its relation with individual body-composition components remains unclear. OBJECTIVE: We aimed to investigate associations between weight gain during different periods in infancy and later fat mass (FM) and fat-free mass (FFM). DESIGN: Body composition was assessed by using the 4-component model, dual-energy X-ray absorptiometry, and anthropometry in 234 healthy UK children and adolescents (105 boys; x +/- SD age: 11.4 +/- 3.8 y). Early growth measurements were prospective in 52 subjects and retrospective in 182. Relative weight gain was calculated as change in SD score (SDS) during different periods. RESULTS: Relative weight gain from 0 to 3 mo and from 3 to 6 mo showed positive relations with childhood FM, waist circumference, and trunk FM that were equivalent to increases in FMI (FM/height(2)) of 0.24 SDS (95% CI: 0.04, 0.44) and 0.50 SDS (0.25, 0.75) per 1-SDS increase in early weight and that were comparable to the effect of current obesity risk factors. Relative weight gain from 0 to 3 mo was also positively associated with later FFMI (FFM/height(2)). Relative weight gain from 6 to 12 mo was not associated with later body composition. Associations were independent of birth weight, sex, puberty, physical activity, socioeconomic class, ethnicity, and parental body mass index. CONCLUSIONS: In this Western population, greater relative weight gain during early infancy was positively associated with later FM and central fat distribution and with FFM. Rapid weight gain in infancy may be a risk factor for later adiposity. Early infancy may provide an opportunity for interventions aimed at reducing later obesity risk.