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Biomedical subjects

N F Butte

Publications and source records attributed to N F Butte.

At least 19 recordsLinked to original sources
PubMed2001

The role of breastfeeding in obesity.

Most studies examining the effects of breastfeeding on later obesity have found an insignificant effect. Breastfeeding was positively associated with later body fatness in two studies. A protective effect of breastfeeding on childhood obesity was seen in four studies. An effect of breastfeeding on later obesity, if any, is probably weaker than genetic and other environmental factors. Also, an observed association between breastfeeding and later obesity does not prove causality. Controlling for confounders in an attempt to minimize the effects of differences between breastfeeding and formula-feeding mothers was done to a varying extent across studies. In several of the later studies, adjustment for confounders obliterated the effect of breastfeeding. Whether all the pertinent confounding factors have been measured and whether the differences between mothers who chose to breastfeed and mothers who chose to formula-feed have been controlled for adequately are always questionable. The dose response observed with the duration of breastfeeding is consistent with a causal association, but confounders associated with breastfeeding also may covary in a graded response. Although a highly provocative concept, the protective effect of breastfeeding on later obesity remains controversial.

Body Composition↗
PubMed2001

Skeletal muscle energetics assessed by (31)P-NMR in prepubertal girls with a familial predisposition to obesity.

OBJECTIVE: To determine whether skeletal muscle energetics, measured by in vivo (31)P-nuclear magnetic resonance spectroscopy during plantar flexion exercise, differ between multiethnic, prepubertal girls with or without a predisposition to obesity. DESIGN: Cross-sectional study. SUBJECTS: Girls (mean age and body fat+/-s.d.=8.6+/-0.3 y and 22.6+/-4.2%) were recruited according to parental leanness or obesity defined as follows: LN (n=22), two lean parents, LNOB (n=18), one lean and one obese parent; and OB (n=15), two obese parents. MEASUREMENTS: A 3 min, rest-exercise-recovery plantar flexion protocol was completed. Work was calculated from the force data. Spectra were analyzed for inorganic intracellular phosphate (P(i)), phosphocreatine (PCr), P(i)/PCr (ratio of the low and high energy phosphates indicating the bioenergetic state of the cell), intracellular pH, and adenosine triphosphate (ATP). Magnetic resonance imaging was used to determine calf muscle volume. RESULTS: BMI was lower in the girls in the LN group (15.9+/-1.5 kg/m(2)) compared to the OB group (16.7+/-1.3 kg/m(2)) of girls (P<0.05), with no difference with the LNOB group (16.7+/-1.9 kg/m(2)). Adjusted for muscle volume and cumulative work, no differences in P(i), PCr, P(i)/PCr, pH, or ATP were observed among the LN, LNOB and OB groups at rest, the end of exercise, and after 60 and 300 s of recovery. From rest to the end of exercise, P(i) and P(i)/PCr (mean+/-s.d.: 0.2+/-0.1 vs 1.5+/-1.0) increased, whereas PCr and pH (7.04+/-0.06 vs 6.95+/-0.10) decreased (all P<0.001). By 60 s of recovery, P(i) and P(i)/PCr decreased, whereas PCr and pH increased (all P<0.001). CONCLUSIONS: Skeletal muscle energetics, specifically P(i)/PCr and pH measured during plantar flexion exercise, do not differ between prepubertal girls with or without a familial predisposition to obesity.

Body Composition↗
PubMed2001

Body composition in prepubertal girls: comparison of six methods.

OBJECTIVE: To compare estimates of fat mass (FM), fat-free mass (FFM) and percentage body fat (%fat) by six different methods in prepubertal girls. DESIGN: Cross-sectional study. SUBJECTS: Normal-weight, multi-ethnic, prepubertal girls (age=8.5+/-0.4 y, n=101). MEASUREMENTS: Body composition was measured in each child by anthropometry (skinfold thickness using Slaughter equation), dual-energy X-ray absorptiometry (DXA), total body potassium (TBK), isotope dilution for total body water measurement (TBW), multifrequency bioelectrical impedance spectroscopy (BIS), and total body electrical conductivity (TOBEC). RESULTS: TOBEC and skinfold thickness yielded the lowest values of FM followed by DXA, TBK, TBW and BIS, with BIS giving the highest value of FM. All methods were significantly different for FFM, FM and %fat (P<0.001), except FFM by DXA and TBK. The Bland-Altman limits of agreement among the methods reveal that they are not directly interchangeable for FM, FFM, or %fat. The largest mean difference for FM was between TOBEC and BIS (-2.90 kg), whereas the smallest mean difference was between TOBEC and skinfold thickness (-0.14 kg). For FFM, the largest mean difference was also between TOBEC and BIS (2.83 kg), but the smallest mean difference for FFM was between DXA and TBK (-0.03 kg). For %fat, the mean differences were larger, -10.5% for TOBEC and BIS and+9.7% for skinfold thickness and BIS. The closest two techniques for %fat were TOBEC and skinfold thickness (mean difference of -0.62%) and DXA and TBK (-1.81%). CONCLUSIONS: We found that estimates of body composition in prepubertal 8-y-old girls are highly method-dependent and that the six methods studied (DXA, TBK, TBW, TOBEC, BIS and anthropometry) are not directly interchangeable.

Absorptiometry, Photon↗
PubMed2001

Familial resemblance of body composition in prepubertal girls and their biological parents.

BACKGROUND: Heritability estimates for body mass index (BMI; in kg/m(2)) in children generally have been derived from twin and adoption studies. However, BMI does not reflect total or regional body composition. OBJECTIVE: We evaluated the familial resemblance of body composition between prepubertal girls of normal weight and body fatness and their parents by using state-of-the-art technology. DESIGN: The subjects were 101 girls [mean age: 8.5 +/- 0.4 y; percentage body fat (%BF): 12-30%] and their biological parents. Weight, height, and body composition [fat mass (FM), fat-free mass (FFM), and %BF] were measured with dual-energy X-ray absorptiometry (DXA) and total body potassium (TBK). RESULTS: Weight, height, and BMI showed low-to-moderate similarity between the girls and both their parents (r = 0.29-0.44, P < 0.01). The girls' FM, FFM, and %BF were significantly related to both parents' body composition. Cross-generational equations were developed for DXA, eg, child's %BF = 12.4 + (0.158 paternal %BF) + (0.145 maternal %BF) (adjusted r(2) = 0.16, P < 0.001). Regional analysis with DXA showed that the adjusted r(2) values for the arm, trunk, and leg regions, respectively, were 0.17, 0.33, and 0.31 for lean tissue mass and 0.11, 0.14, and 0.09 for FM. TBK showed a similar relation between parents and girls (r = 0.28-0.47, P < 0.01). Significant heritability (h(2) +/- SE) was detected for BMI (0.35 +/- 0.17, P = 0.03) and %BF measured with DXA (0.50 +/- 0.12, P = 0.0001). CONCLUSION: The body composition of prepubertal girls of normal weight and body fatness is significantly related to the body composition of both biological parents.

Absorptiometry, Photon↗
PubMed2001

Energy requirements of lactating women derived from doubly labeled water and milk energy output.

Instead of using an incremental approach to assess the energy requirements of lactation, a more comprehensive approach may be taken by measuring total energy expenditure (TEE), milk energy output and energy mobilization from tissue stores. The latter approach avoids assumptions regarding energetic efficiency and changes in physical activity and adiposity. The purpose of this study was threefold: to assess the energy requirements of lactation; to compare these estimates with energy requirements in the nonpregnant, nonlactating state and to test for energetic adaptations in basal metabolic rate (BMR) and physical activity during the energy-demanding process of lactation. Milk production and composition, body weight and composition, TEE, BMR and physical activity levels were measured in 24 well-nourished women during exclusive breastfeeding at 3 mo postpartum and after the cessation of breastfeeding at 18 or 24 mo postpartum. TEE was measured by the doubly labeled water method, milk production by 3-d test-weighing, milk energy by bomb calorimetry on a 24-h milk sample, body composition by dual-energy x-ray absorptiometry and BMR by room respiration calorimetry. TEE, BMR and physical activity level (physical activity level = TEE/BMR) did not differ between the lactating and nonlactating state (TEE 10.0 +/- 1.5 versus 10.6 +/- 2.1 MJ/d). Mean milk energy output was equivalent to 2.02 +/- 0.33 MJ/d. Total energy requirements were greater during lactation than afterward (12.0 +/- 1.4 versus 10.6 +/- 2.1 MJ/d, P: = 0.002). Energy mobilization from tissue stores (-0.65 +/- 0.97 MJ/d) resulted in net energy requirements during lactation of 11.4 +/- 1.8 MJ/d. Because adaptations in basal metabolism and physical activity were not evident in these well-nourished women, energy requirements during lactation were met primarily from the diet and only partially by mobilization of tissue stores.

Adult↗
PubMed2001

Glucose production, gluconeogenesis, and insulin sensitivity in children and adolescents: an evaluation of their reproducibility.

The prevalence of overweight and obese children has doubled, and the incidence of type 2 diabetes in children (0-19 y) has increased 4-fold during the past several decades. As a result we can anticipate an increased number of metabolic studies in children. There are few data on measures of glucose metabolism in normal children, and virtually none relating to their reproducibility. The aims of this study were 1) to provide new data on energy expenditure and glucose, lipid, and protein metabolism in nonobese, healthy children and adolescents; 2) to evaluate their reproducibility; and 3) on the basis of these data, to perform power calculations for metabolic studies. Eight nonobese subjects (8-16 y) were studied on two occasions, preceded by 7 d of a diet with identical energy content and macronutrient distribution. Gluconeogenesis, measured by deuterium oxide, accounted for 50% of glucose production. Insulin sensitivity, measured by the labeled minimal model, averaged 4.9 x 10(-4) mL(mU x min)(-1). Glucose appearance rate was significantly higher (p < 0.01) in the children than in the adolescents. Furthermore, we demonstrated that for energy intake and expenditure, plasma concentrations of glucose and C-peptide, and rates of appearance of glucose and leucine, a 10% difference can be detected in fewer than five subjects with a power of 80% and a type I error of 5%. Insulin concentration, gluconeogenesis, insulin secretory indices, insulin sensitivity, and glucose effectiveness were more variable, but with the above power a difference of 25% could be detected in 7-11 subjects using a paired study design.

Adolescent↗
PubMed2000

Profound obesity associated with a balanced translocation that disrupts the SIM1 gene.

Studies of mice and humans have revealed a number of genes that when mutated result in severe obesity. We have studied a unique girl with early-onset obesity and a de novo balanced translocation between chromosomes 1p22.1 and 6q16.2. Her weight gain is most likely due to excessive food intake, since measured energy expenditure was normal. We cloned and sequenced both translocation breakpoints. The translocation does not appear to affect any transcription unit on 1p, but it disrupts the SIM1 gene on 6q. SIM1 encodes a human homolog of Drosophila Sim (Single-minded), a transcription factor involved in midline neurogenesis, and is a prototypical member of the bHLH-PAS (basic helix-loop-helix + period, aryl hydrocarbon receptor, Single-minded) gene family. Our subject's trans- location separates the 5' promoter region and bHLH domain from the 3' PAS and putative transcriptional regulation domains. The transcriptional targets of SIM1 are not known. Mouse Sim1 is expressed in the developing kidney and central nervous system, and is essential for formation of the supraoptic and paraventricular (PVN) nuclei of the hypothalamus. Previous neuroanatomical and pharmacological studies have implicated the PVN in the regulation of body weight: PVN neurons express the melanocortin 4 receptor and appear to be physiological targets of alpha-melanocyte-stimulating hormone, which inhibits food intake. We hypothesize that haploinsufficiency of SIM1, possibly acting upstream or downstream of the melanocortin 4 receptor in the PVN, is responsible for severe obesity in our subject.

Age of Onset↗
PubMed2000

Estimation of body fat in Caucasian and African-American girls: total-body electrical conductivity methodology versus a four-component model.

BACKGROUND: Obesity has been increasing dramatically in recent years among children, particularly African-American girls. Total-body electrical conductivity (TOBEC) is a simple way to measure body fat with minimal risk. OBJECTIVE: This study compared the agreement between the percentage of fat mass (%FM) predicted using two TOBEC equations with %FM measured by a four-component model in 73 Caucasian and 41 African-American girls. DESIGN AND MEASUREMENTS: %FM predicted using the TOBEC equations was compared with %FM from the four-component model based on measurements of body density, body water and bone mineral content. RESULTS: Analyses by linear regression analysis and by the Bland and Altman methods comparison procedure showed that the equation using the square root of the TOBEC zero-order Fourier coefficient and the subject's height yielded more accurate and more reproducible %FM, regardless of race, than the TOBEC linear equation, which was based on the zero-, first- and second-order Fourier coefficients. The Bland and Altman comparison further revealed that the accuracy and limits of agreement of the TOBEC linear equation were related to body fatness among the Caucasian girls. The relationship, however, disappeared when prepubescent girls and a girl with low %FM were excluded from the analysis. CONCLUSIONS: The TOBEC square root equation with adjustment for body geometry and length is recommended for use in adolescent girls, as it yielded better agreement with the criterion method. However, further validation of the TOBEC instrumentation for estimating body fat in prepubescent children and children with low body fat is warranted.

Absorptiometry, Photon↗
PubMed2000

Effects of familial predisposition to obesity on energy expenditure in multiethnic prepubertal girls.

BACKGROUND: The prevalence of childhood obesity is increasing and the causes of this are unknown. OBJECTIVE: The objective of this study was to determine whether energy expenditure (EE), measured by 24-h calorimetry and doubly labeled water, differed in normal-weight-for-height, multiethnic prepubertal girls with or without a familial predisposition to obesity. DESIGN: Normal-weight, prepubertal white (n = 52), African American (n = 30), and Hispanic (n = 19) girls with a mean (+/-SD) age of 8.5 +/- 0.4 y were studied according to parental leanness and overweight or obesity. The girls were grouped according to whether they had 2 lean parents (n = 30), 2 obese parents (n = 27), or 1 lean and 1 obese parent (n = 44). Basal metabolic rate (BMR), sleeping metabolic rate (SMR), 24-h EE, respiratory quotient, heart rate, and activity were measured by 24-h room calorimetry; free-living total EE (TEE), activity-related EE (AEE), and physical activity level were measured by doubly labeled water. EE was standardized by fat-free mass (FFM). RESULTS: There were no significant differences among familial groups in weight, height, fat mass, FFM, or percentage body fat. African American girls had a higher FFM than did white or Hispanic girls (P < 0.05). BMR, SMR, 24-h EE, respiratory quotient, heart rate, and activity levels were not significantly different among familial groups. Additionally, there were no significant familial group differences in TEE, AEE, or physical activity level. However, BMR, SMR, and TEE were lower in African American girls than in white girls (P < 0.05). CONCLUSION: There was no significant difference in EE between normal-weight, multiethnic prepubertal girls predisposed to obesity and those not predisposed to obesity.

Basal Metabolism↗
PubMed2000

Carbohydrate and lipid metabolism in pregnancy: normal compared with gestational diabetes mellitus.

This article reviews maternal metabolic strategies for accommodating fetal nutrient requirements in normal pregnancy and in gestational diabetes mellitus (GDM). Pregnancy is characterized by a progressive increase in nutrient-stimulated insulin responses despite an only minor deterioration in glucose tolerance, consistent with progressive insulin resistance. The hyperinsulinemic-euglycemic glucose clamp technique and intravenous-glucose-tolerance test have indicated that insulin action in late normal pregnancy is 50-70% lower than in nonpregnant women. Metabolic adaptations do not fully compensate in GDM and glucose intolerance ensues. GDM may reflect a predisposition to type 2 diabetes or may be an extreme manifestation of metabolic alterations that normally occur in pregnancy. In normal pregnant women, basal endogenous hepatic glucose production (R(a)) was shown to increase by 16-30% to meet the increasing needs of the placenta and fetus. Total gluconeogenesis is increased in late gestation, although the fractional contribution of total gluconeogenesis to R(a), quantified from (2)H enrichment on carbon 5 of glucose (65-85%), does not differ in pregnant women after a 16-h fast. Endogenous hepatic glucose production was shown to remain sensitive to increased insulin concentration in normal pregnancy (96% suppression), but is less sensitive in GDM (80%). Commensurate with the increased rate of glucose appearance, an increased contribution of carbohydrate to oxidative metabolism has been observed in late pregnancy compared with pregravid states. The 24-h respiratory quotient is significantly higher in late pregnancy than postpartum. Recent advances in carbohydrate metabolism during pregnancy suggest that preventive measures should be aimed at improving insulin sensitivity in women predisposed to GDM. Further research is needed to elucidate the mechanisms and consequences of alterations in lipid metabolism during pregnancy.

Diabetes, Gestational↗
PubMed2000

Estimating body fat in African American and white adolescent girls: a comparison of skinfold-thickness equations with a 4-compartment criterion model.

BACKGROUND: Although skinfold-thickness equations are widely used to estimate body fat, their accuracy in a biracial population of female adolescents has not been established. OBJECTIVE: We undertook this study to determine the agreement between 8 widely used skinfold-thickness equations and a 4-compartment criterion model in predicting the percentage body fat of 72 white and 40 African American girls aged 13.0 +/- 1.9 y. DESIGN: The biceps, triceps, suprailiac, subscapular, thigh, calf, and abdominal skinfold thicknesses of the subjects were measured with skinfold calipers and the buttocks circumference with a metal tape. The percentage fat mass (%FM) predicted by using each skinfold-thickness equation was compared with the criterion value calculated by the 4-compartment model on the basis of measurements of body density, body water, and bone mineral content. RESULTS: When the racial groups were analyzed separately, the Bland-Altman analysis indicated that the quadratic equations agreed most closely with the 4-compartment model's measurement of %FM. Agreement of the other equations varied with body fatness. CONCLUSIONS: The quadratic equation of Slaughter et al is recommended for population studies in female adolescents because of its accuracy and simplicity. However, an individual %FM can be over- or underestimated by approximately 10% when this skinfold-thickness equation is used.

Adipose Tissue↗
PubMed2000

Fat intake of children in relation to energy requirements.

The optimal fat intake for children is discussed in light of their energy requirements. Total energy requirements were estimated from doubly labeled water studies of total energy expenditure (TEE) and the energy cost of growth. Basal metabolic rates (BMRs) were calculated from weight by using the equations of Schofield et al or by indirect calorimetry. Activity energy expenditure and physical activity levels were calculated as TEE - BMR and TEE/BMR, respectively. Weight-specific energy requirements for maintenance and growth changed inversely to the increased energy needed for physical activity in healthy, active children. The total energy requirements of infants increased from 1.4 MJ/d at 1 mo to 4.0 MJ/d at 24 mo. The energy cost of growth decreased sharply from 37-38% to 2% of the total requirement during the first 24 mo of life. Energy requirements increased from 4 MJ/d at 2 y to 11 MJ/d at 18 y in girls and from 5 to 15 MJ/d in boys. The energy cost of growth varied between 1% and 4% of total energy requirements in childhood and adolescence. The current recommendation of 30% of energy from dietary fat for children aged >2 y is sufficient for adequate growth. Lower fat intakes may be associated with inadequate vitamin and mineral intakes and increased risk of poor growth. Diets higher in fat may lead to higher energy intakes and higher body fat, although available data for children are conflicting. Beyond infancy, children can meet their energy needs for maintenance, physical activity, and growth from a diet providing 30% of energy from fat.

Adolescent↗
PubMed2000

Energy requirements derived from total energy expenditure and energy deposition during the first 2 y of life.

BACKGROUND: Current recommendations for energy intake of children are derived from observed intakes. Deriving energy requirements on the basis of energy expenditure and deposition is scientifically more rational than is using the observational approach and is now possible with data on total energy expenditure (TEE), growth, and body composition. OBJECTIVES: The objectives of this study were 1) to define energy requirements during the first 2 y of life on the basis of TEE and energy deposition; 2) to test effects of sex, age, and feeding mode on energy requirements; and 3) to determine physical activity. DESIGN: TEE, sleeping metabolic rate, anthropometry, and body composition were measured in 76 infants. TEE was measured with doubly labeled water, sleeping metabolic rate with respiratory calorimetry, and body composition with a multicomponent model. RESULTS: Total energy requirements were 2.23, 2.59, 2.97, 3. 38, 3.72, and 4.15 MJ/d at 3, 6, 9, 12, 18, and 24 mo, respectively. Energy deposition (in MJ/d) decreased significantly over time (P: = 0.001) and was lower in breast-fed than in formula-fed infants (P: = 0.01). Energy requirements were approximately 80% of current recommendations. Energy requirements differed by age (P: = 0.001), feeding group (P: = 0.03), and sex (P: = 0.03). Adjusted for weight or fat-free mass and fat mass, energy requirements still differed by feeding group but not by age or sex. Temperament and motor development did not affect TEE. CONCLUSION: The TEE and energy-deposition data of these healthy, thriving children provide strong evidence that current recommendations for energy intake in the first 2 y of life should be revised.

Anthropometry↗
PubMed2000

Lactation delays postpartum bone mineral accretion and temporarily alters its regional distribution in women.

The objective of this work was to compare long-term changes in bone mineral in lactating (L) and nonlactating (NL) women for 2 y postpartum. The 40 L women (mean duration of breastfeeding 345 +/- 177 d) and 36 NL women were enrolled during late pregnancy. Subjects were healthy and nonsmoking with a mean age of 28.8 +/- 4.1 y. Bone mineral content (BMC) was measured at 0.5, 3, 6, 12, 18 and 24 mo by dual-energy X-ray absorptiometry set for total body scan with regional analysis. BMC adjusted for bone area, weight and height (adj-BMC) decreased in L women at the lumbar spine (-3.1%, P < 0. 001) and pelvis (-0.9%, P = 0.03) by 3 mo, and at the total body (-0. 9%, P = 0.05) by 6 mo. Losses were recovered following onset of menses. Adj-BMC at the lumbar spine, pelvis, thoracic spine and total body increased over baseline by 24 mo in L women. In NL women, adj-BMC increased over baseline within 3 mo and continued to increase thereafter. Net total-body gains were greater in the 27 NL women who completed the final measurement than in their 26 L counterparts (+2.3% vs. +0.6%, P = 0.001). Net regional gains differed at the head, legs, and ribs, but not at the lumber spine, pelvis or thoracic spine. Duration of breastfeeding, parity, onset of menses and maternal age affected bone changes in L women. These results indicate that lactation delays bone mineral accretion and temporarily alters its regional distribution in postpartum women.

Adult↗
PubMed2000

Body composition during the first 2 years of life: an updated reference.

Normative body composition during the first 2 y of life was derived from a prospective study of 76 children. We present 1) fat free mass (FFM) and its components, and fat mass (FM), 2) incremental growth rates partitioned into chemical components, and 3) age-specific and gender-specific constants for converting chemical and physical components into FFM for children during the first 2 y of life. A multicomponent model based on measurements of total body water (TBW), total body potassium (TBK) and bone mineral content (BMC) was used to estimate FFM and FM at 0.5, 3, 6, 9, 12, 18, and 24 mo of age. TBW was determined by deuterium dilution, TBK by whole body counting, and BMC by dual energy x-ray absorptiometry. FFM was higher in boys than girls between 0.5-18 mo of age (p < or = 0.05). Percent FM increased on average from 13 to 31% between 0.5 and 3-6 mo, and then gradually declined. Percent FM was significantly higher in girls than in boys at 6 and 9 mo of age (p < or = 0.02). The components of FFM on a percentage basis changed with age (p = 0.001), but not gender. The protein content of FFM increased gradually with age, while TBW declined (p = 0.001). As a percentage of FFM, osseous mineral increased from 2.0 to 3.4% in boys and from 2.1 to 3.3% in girls between 0.5 and 24 mo (p = 0.001). Density and potassium content of FFM increased gradually with age (p = 0.001). These normative body composition data provide an updated reference upon which to assess normal growth and nutritional status of pediatric populations representative of mixed feeding groups during the first 2 y of life.

Absorptiometry, Photon↗
PubMed2000

Relations of parental obesity status to physical activity and fitness of prepubertal girls.

OBJECTIVE: To determine whether physical activity and fitness differ among normal-weight-for-height, multiethnic, prepubertal girls whose parents are lean, obese, or both. SETTING: Conducted in Houston, Texas. STUDY PARTICIPANTS: Normal-weight white, black, and Hispanic prepubertal girls (mean age +/- standard deviation: 8.5 +/-.4 years) participated in this study. Girls were recruited according to parental leanness or obesity defined as follows: girls with 2 lean parents (LN group; n = 30); girls with 2 obese parents (OB group; n = 27); and girls with 1 lean and 1 obese parent (LNOB group; n = 44). Intervention. Each child wore a heart rate monitor for two 24-hour periods, underwent a treadmill exercise test, answered an activity questionnaire, and completed energy expenditure measurements by basal calorimetry and doubly labeled water. OUTCOME MEASURES: The amount of time spent above 125% and 150% of basal heart rate (BHR) was calculated during each 24-hour period (n = 84). Fitness (n = 97), habitual physical activity (n = 101), and physical activity level (PAL = total energy expenditure/basal metabolic rate; n = 101) were also measured. RESULTS: The times spent above 125% and 150% of BHR were similar among LN, LNOB, and OB groups. Black girls spent less time than did white girls on the weekend above 125% BHR and above 150% BHR. No significant familial or ethnic differences in peak oxygen consumption or habitual physical activity were observed. PALs were as follows: LN = 1.6 +/-.21; LNOB = 1.64 +/-.27; OB = 1.58 +/-. 20; white = 1.63 +/-.23; black = 1.58 +/-.24; and Hispanic = 1.65 +/-.25. PAL was related to time spent above 125% BHR and 150% BHR (r =.31,.39). CONCLUSIONS: Physical activity and fitness of normal-weight prepubertal girls predisposed to obesity did not differ from girls without a family history of obesity. obesity, children, energy metabolism, exercise, heart rate monitoring.

Body Composition↗
PubMed2000

Infant feeding mode affects early growth and body composition.

BACKGROUND: Differences in the growth pattern of breastfed (BF) and formula-fed (FF) infants are well-recognized and have been attributed to differences in nutrient intake. However, the impact of qualitative and quantitative differences in nutrient intake on the body composition of BF and FF infants has been unclear. Furthermore, it is unknown whether putative differences in body composition persist beyond weaning. DESIGN: Prospective cohort study. METHODS: Repeated anthropometric and body composition measurements were performed on 40 BF and 36 FF infants at 0.5, 3, 6, 9, 12, 18, and 24 months of age. A multicomponent body composition model based on total body water by deuterium dilution, total body potassium by whole body counting, and bone mineral content by dual-energy x-ray absorptiometry was used to estimate fat-free mass (FFM) and fat mass (FM). Independent measurements of FFM and FM were made using total body electrical conductivity and dual-energy x-ray absorptiometry. By design, infants were either exclusively BF or FF from birth to 4 months of age; thereafter, the feeding mode was at the discretion of the parents. Infant food intake was measured at 3, 6, 12, and 24 months of age using 3-day weighed-intake records. Data were analyzed by repeated measures analysis of variance. RESULTS: Weight velocity was higher in FF than BF infants age 3 to 6 months, and higher in FF than BF girls 6 to 9 months of age. Adjusted for gender and baseline values, BF infants had lower total body water at 3 months, lower total body potassium at 3 to 24 months, and lower bone mineral content at 12 months. The multicomponent model indicated that FFM was lower in BF than FF infants at 3 months, and FM and %FM were higher in BF than FF infants at 3 and 6 months (boys only). Total body electric conductivity confirmed lower FFM in BF than FF infants at 3 months, as well as at 6 and 9 months; FM and %FM were higher in BF than FF at 3 and 6 months, and 9 months (boys only). Intakes of energy, protein, fat, and carbohydrate were lower in BF than FF infants at 3 and 6 months, and were positively correlated with weight gain and FFM gain, but not FM gain. No differences in nutrient intakes were observed at 12 or 24 months. CONCLUSION: Infant feeding mode is associated with differences in body composition in early infancy which do not persist into the second year of life.

Absorptiometry, Photon↗