Higher baseline resting metabolic rate is associated with 1-year frailty decline among older adults residing in an urban area.

BACKGROUND: Dysregulated energy metabolism is one hypothesized mechanism underlying frailty. Resting energy expenditure, as reflected by resting metabolic rate (RMR), makes up the largest component of total energy expenditure. Prior work relating RMR to frailty has largely been done in cross section with mixed results. We investigated whether and how RMR related to 1-year frailty change while adjusting for body composition. METHODS: N = 116 urban, predominantly African-American older adults were recruited between 2011 and 2019. One-year frailty phenotype (0-5) was regressed on baseline RMR, frailty phenotype, demographics and body composition (DEXA) in an ordinal logistic regression model. Multimorbidity (Charlson comorbidity scale, polypharmacy) and cognitive function (Montreal Cognitive Assessment) were separately added to the model to assess for change to the RMR-frailty relationship. The model was then stratified by baseline frailty status (non-frail, pre-frail) to explore differential RMR effects across frailty. RESULTS: Higher baseline RMR was associated with worse 1-year frailty (odds ratio = 1.006 for each kcal/day, p = 0.001) independent of baseline frailty, demographics, and body composition. Lower fat-free mass (odds ratio = 0.88 per kg mass, p = 0.008) was independently associated with worse 1-year frailty scores. Neither multimorbidity nor cognitive function altered these relationships. The associations between worse 1-year frailty and higher baseline RMR (odds ratio = 1.009, p < 0.001) and lower baseline fat-free mass (odds ratio = 0.81, p = 0.006) were strongest among those who were pre-frail at baseline. DISCUSSION: We are among the first to relate RMR to 1-year change in frailty scores. Those with higher baseline RMR and lower fat-free mass had worse 1-year frailty scores, but these relationships were strongest among adults who were pre-frail at baseline. These relationships were not explained by chronic disease or impaired cognition. These results provide new evidence suggesting higher resting energy expenditure is associated with accelerate frailty decline.

Vaginal prevalence of human papillomavirus infections in women with uterovaginal aplasia before and after laparoscopically assisted creation of a neovagina: a prospective epidemiological observational study.

OBJECTIVE: To study vaginal as opposed to cervical human papillomavirus (HPV) acquisition with regard to true prevalence, HPV types, and the role of co-factors in virgins and after their sexual debut. DESIGN: Prospective epidemiological observational study. SETTING: University hospital specialised in genital malformations. POPULATION: Women diagnosed with Mayer-Rokitansky-Küster-Hauser syndrome (MRKHS) and undergoing neovaginoplasty between November 2011 and July 2017. METHODS: This is a prospective study including 186 women with MRKHS before and after sexual debut. MAIN OUTCOME MEASURES: Conventional vaginal cytology and different HPV tests were performed at surgery and during routine gynaecological follow-up 1, 3, 6 and ≥ 11 months after surgery and risk factors were documented. RESULTS: The mean age of all women at surgery was 20.1 years (SD 5.4), mean body mass index (BMI) was 22.1 kg/m2 (SD 4.6). In 83 vaginal samples from 41 different women at least one of the HPV tests was positive. Thirty-three different HPV types were detected. The prevalence of 41/186 = 22.0% as well as type distribution are comparable with those found in a young German female population. The overall rate of acquisition was clearly associated with sexual activity and smoking habits. Out of 367 Papanicolaou smears only six were abnormal with Pap IIID (MN II) and no obvious vaginal lesion was detected. CONCLUSIONS: Vaginal HPV prevalence and HPV types in previously virgin women after creation of a neovagina are not different from the acquisition of cervical infections in the general population and is clearly associated with sexual activity and with smoking habits. However, abnormal Papanicolaou smears are rarely seen. TWEETABLE ABSTRACT: Vaginal HPV prevalence after creation of a neovagina is similar to that on the cervix in the general population.

Circannual variation in relative weight of children 5 to 16 years of age.

BACKGROUND: Summer weight gain in children has been reported; however, this is usually based on two time points. Our objective was to investigate monthly variation in weight status. METHODS: Cross-sectional, de-identified health records including height, weight and demographics, collected between 2007 and 2012 from South Central Wisconsin in 70 531 children age 5-16 years were analysed. The monthly averages in body mass index (BMI) z-score were analysed cross-sectionally followed by a paired analysis for a subset with one visit each during school and summer months. RESULTS: BMI z-scores during the summer months (June-August) were lower than values during the school year (September-May). Of note, there was a rapid decrease in BMI z-scores from May to June, with June BMI z-score values being 0.065 units less (95% CI 0.046-0.085) than those in May, little change from June to August and a rapid increase between the August and September BMI z-scores. CONCLUSION: The monthly pattern does not fully agree with previous two-point school-based studies. Results raise concern that the use of two time point measures of BMIs (early fall and late spring) is suboptimal for evaluation of circannual variation. We suggest that future evaluation of the effect of school-based or summer interventions utilizes additional measures in those periods so that a seasonal analysis can be performed.

High energy expenditure is not protective against increased adiposity in children.

BACKGROUND: Low levels of energy expenditure (TEE) may contribute to excess weight during childhood, but limited longitudinal data exist. OBJECTIVES: This is to test whether low TEE during the first 6 years of life could predict excess weight status at 8 years. METHODS: Total energy expenditure from doubly labelled water, weight, stature, waist circumference and fat mass and fat-free mass (FFM) in children at 0.25, 2, 4 and 6 years of age. This cohort includes individuals at high (n = 27) and low risk (n = 26) for childhood obesity, based upon whether pre-pregnant maternal obesity. A linear mixed effects model was fit to TEE. Individual variation was accounted for as a random effect. Residual TEE was calculated for age and individually averaged across time. RESULTS: Fat-free mass (kg) was highly correlated (R2 = 0.91) with TEE (kcal/day), and waist circumference and sex were also significant predictors of TEE. TEE residual tracked within individuals. TEE residuals did not correlate with either BMI or %fat at age 8 years. CONCLUSION: Using the residual TEE approach to identify high and low TEE during the first 6 years of life did not explain excess weight at 8 years of life in this cohort of children at high and low risk of obesity based upon maternal obesity status.

Familial and individual predictors of obesity and insulin resistance in urban Hispanic children.

BACKGROUND: High intake of sugar-sweetened beverages (SSB) has been suggested to contribute to the pediatric obesity epidemic, however, how the home food environment influence children's intake of SSB among Hispanic families is still poorly understood. OBJECTIVES: To evaluate the relationships between the home food environment and Hispanic children's diet in relation to weight status and insulin resistance (IR). METHODS: A food frequency questionnaire was administered to 187 Hispanic children (ages 10 to 14 years) and anthropometrics were measured. IR was estimated from fasting insulin and glucose levels using the homeostasis model assessment of insulin resistance (HOMAIR ). Parents reported on family demographics and the home food environment. A structural equation modelling approach was applied to examine the hypothesized relationships among variables. RESULTS: The prevalence of childhood overweight and obesity was 52.8% and it was positively associated with HOMAIR (ß = 0.687, P < .0001). Children's SSB consumption was positively associated with children's body mass index z-score (ß = 0.151, P < 0.05) and subsequently to HOMAIR . Children's SSB consumption was predicted by home availability (ß = 0.191) and parental intake of SSB (ß = 0.419) (P < 0.05). The model fit indices [χ(2) = 45.821 (d.f. = 30, P > 0.01 and < 0.05), χ(2) /d.f. = 1.53, root mean square error of approximation = 0.053 (90% confidence interval = 0.016, 0.082), comparative fit index = 0.904] suggested a satisfactory goodness-of-fit. CONCLUSIONS: The home food environment and parental diet seem to play an important role in the children's access to and intake of SSB, which in turn predicted children's weight status.

The Association between Screen Time and Weight Status in Hispanic Children.

BACKGROUND: About one-third of U.S. children are overweight or obese and the number is even higher among Hispanics children (41%). In this regards, the time spent in sedentary behaviours is higher among Hispanic children versus non-Hispanic white children. But whether the home environment contributes to the obesity disparity among Hispanic children through the promotion of sedentary behaviours at home is less known. We aimed to investigate the associations between the home environment, parental limiting, and screen time with Hispanic children's body weight. METHODS: Study participants were middle school Hispanic children (n=187), ages 10-14 years and their parents. Children's anthropometrics were measured and used to calculate BMI z-scores. Questionnaires were used to assess children's time spent on physical activity (PA), sedentary activities, and to query parents on the home environment and parental limiting. RESULTS: Total time (h/d) spent watching television (TV) was positively associated with children's BMI z-score (P=0.02). However, no association was found between total screen time (TV, video games, and computer) and PA and with children's BMI z-score. Sleeping time (h/d) was inversely associated with children's BMI z-score (P=0.02); while there was a significant interaction between sleeping time and gender (P-interaction=0.02). Further, having a screen in the bedroom was positively associated with children's TV and total screen time (P<0.05); while parental limits on screen time was inversely associated with children's screen time (P<0.05). CONCLUSIONS: Screen and sleep time may contribute to higher body weight among Hispanic children, independently of associations with physical activity. Our findings suggest a differential effect of gender in the contribution of sleep time to higher body weight, in that girls spent less time sleeping when compared to boys. These findings can inform obesity-prevention efforts to intervene at the family level in improving sleeping patterns and increasing physical activity while reducing sedentary opportunities at home.

Assessing Children's Time-Use in Relation to Physical Fitness and Risks of Obesity and Diabetes: Development of a New Physical Activity Self-Report Instrument.

BACKGROUND: This study introduces a novel self-report instrument to measure children's time-use in physical and sedentary activities and examines the relationships between children's time-use and physical fitness and risks of obesity and diabetes. METHODS: The new instrument utilizes a series of timelines, each representing an activity type. 188 children (53% girls) aged 10 to 14 year-old participated in the study. Their time-use data for two weekdays and one weekend day were collected. Anthropometrics and cardiovascular fitness were measured and children's BMI z-score and PACER z-score were computed. One-time blood draw for fasting glucose and insulin were used to calculate insulin resistance using homeostasis model assessment for insulin resistance (HOMAIR). RESULTS: The reliability assessment of this instrument indicated a moderately reproducible procedure (ICC > 0.6) for six activity types. The validity correlation for motorized travel time was high (r = 0.226, P < 0.05) between self-report instrument and GPS tracks. PACER z-score was positively correlated with time-uses of play (r = 0.159, P < 0.05), and organized sports (r = 0.198, P < 0.05); and was highly inversely correlated with BMI z-score (r = -0.441, P < 0.0001) and HOMAIR (r = -0.472, P < 0.0001). Overall, only 14% of the children had physical activity for more than 60 minutes daily over three observation days. CONCLUSIONS: This instrument is particularly useful in assessing children's activity patterns, especially for specific physical activities. The new instrument provides a reproducible measure of children's perception of their activities. Our results emphasize the temporal context which is critical to formulating effective interventions targeting physical activity increase in children. Further efforts are needed to understand the differences between activity time obtained by the new self-report instrument and GPS tracks.

Energy balance measurement: when something is not better than nothing.

Energy intake (EI) and physical activity energy expenditure (PAEE) are key modifiable determinants of energy balance, traditionally assessed by self-report despite its repeated demonstration of considerable inaccuracies. We argue here that it is time to move from the common view that self-reports of EI and PAEE are imperfect, but nevertheless deserving of use, to a view commensurate with the evidence that self-reports of EI and PAEE are so poor that they are wholly unacceptable for scientific research on EI and PAEE. While new strategies for objectively determining energy balance are in their infancy, it is unacceptable to use decidedly inaccurate instruments, which may misguide health-care policies, future research and clinical judgment. The scientific and medical communities should discontinue reliance on self-reported EI and PAEE. Researchers and sponsors should develop objective measures of energy balance.

Breath carbon stable isotope ratios identify changes in energy balance and substrate utilization in humans.

Rapid detection of shifts in substrate utilization and energy balance would provide a compelling biofeedback tool for individuals attempting weight loss. As a proof of concept, we tested whether the natural abundance of exhaled carbon stable isotope ratios (breath δ(13)C) reflects shifts between negative and positive energy balance. Volunteers (n=5) consumed a 40% energy-restricted diet for 6 days followed by 50% excess on day 7. Breath was sampled immediately before and 1 h and 2 h after breakfast, lunch and dinner. Exhaled breath δ(13)C values were measured by cavity ring-down spectroscopy. Using repeated measures analysis of variance (ANOVA) followed by Dunnett's contrasts, pre-breakfast breath values on days 2-6 were compared with day 1, and postprandial day 7 time points were compared with pre-breakfast day 7. Energy restriction diminished pre-breakfast breath δ(13)C by day 3 (P<0.05). On day 7, increased energy intake was first detected immediately before dinner (-23.8±0.6 vs -21.9±0.7‰, P=0.002 (means±s.d.)), and breath δ(13)C remained elevated at least 2 h post dinner. In conclusion, when shifting between negative and positive energy balance, breath δ(13)C showed anticipated isotopic changes. Although additional research is needed to determine specificity and repeatability, this method may provide a biomarker for marked increases in caloric intake.

Prediction of fat-free mass using bioelectrical impedance analysis in young adults from five populations of African origin.

BACKGROUND/OBJECTIVES: Bioelectrical impedance analysis (BIA) is used in population and clinical studies as a technique for estimating body composition. Because of significant under-representation in existing literature, we sought to develop and validate predictive equation(s) for BIA for studies in populations of African origin. SUBJECTS/METHODS: Among five cohorts of the Modeling the Epidemiologic Transition Study, height, weight, waist circumference and body composition, using isotope dilution, were measured in 362 adults, ages 25-45 with mean body mass indexes ranging from 24 to 32. BIA measures of resistance and reactance were measured using tetrapolar placement of electrodes and the same model of analyzer across sites (BIA 101Q, RJL Systems). Multiple linear regression analysis was used to develop equations for predicting fat-free mass (FFM), as measured by isotope dilution; covariates included sex, age, waist, reactance and height(2)/resistance, along with dummy variables for each site. Developed equations were then tested in a validation sample; FFM predicted by previously published equations were tested in the total sample. RESULTS: A site-combined equation and site-specific equations were developed. The mean differences between FFM (reference) and FFM predicted by the study-derived equations were between 0.4 and 0.6 kg (that is, 1% difference between the actual and predicted FFM), and the measured and predicted values were highly correlated. The site-combined equation performed slightly better than the site-specific equations and the previously published equations. CONCLUSIONS: Relatively small differences exist between BIA equations to estimate FFM, whether study-derived or published equations, although the site-combined equation performed slightly better than others. The study-derived equations provide an important tool for research in these understudied populations.

Comparison of total energy expenditure between school and summer months.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT: Childhood obesity has increased 3 to 4 fold. Some children gain excess weight in summer. WHAT THIS STUDY ADDS: Total energy expenditure increases almost linearly with fat-free mass. A lower total energy expenditure was not detected in summer. OBJECTIVE: Recent data report that the youth experience greater weight gain during summer than during school months. We tested the hypothesis that a difference in total energy expenditure (TEE) between school and summer months exists and may contribute to summer weight gain. SUBJECTS AND METHODS: A secondary analysis was performed on cross-sectional TEE data from school-age, sedentary African-American and Caucasian youth based in or near the District of Columbia who were at-risk for adult obesity because they had body mass index (BMI) ≥ 85th percentile or had overweight parents. TEE was estimated from 18-O and deuterium measurements during 1-week intervals using urine samples collected after ingestion of doubly labelled water. Differences in summer- and school-time TEE were assessed using analysis of covariance. The data were adjusted for fat-free mass (FFM) as determined by deuterium dilution to adjust for the effect of body size on TEE. RESULTS: Data were collected from 162 youth (average age 10 ± 2 years, BMI 28 ± 8 kg m(-2) and BMI z-score 1.96 + 0.96). Of these, 96 youth had TEE measured during the school year (September-June); 66 different youths had TEE measured during summer months (June-August). After adjustment for FFM, average summertime TEE was 2450 ± 270 kcal d(-1) and average school-time TEE was 2510 ± 350 kcal d(-1) (P = 0.26). CONCLUSION: No difference in TEE was detected between the school year and the summer months. These data suggest that seasonal differences in youth weight gain are not necessarily due to differences in energy expenditures.

Effect of clothing weight on body weight.

BACKGROUND: In clinical settings, it is common to measure weight of clothed patients and estimate a correction for the weight of clothing, but we can find no papers in the medical literature regarding the variability in clothing weight of adults with weather, season and gender. METHODS: Fifty adults (35 women) were weighed four times during a 12-month period with and without clothing. Clothing weights were determined and regressed against minimum, maximum and average daily outdoor temperature. RESULTS: The average clothing weight (±s.d.) throughout the year was significantly greater in men than in women (1.2±0.3 vs 0.8±0.3 kg, P<0.0001). The average within-person minimum and the average within-person maximum clothing weights across the year were 0.9±0.2 and 1.5±0.4 kg for men, and 0.5±0.2 and 1.1±0.4 kg for women, respectively. The within-person s.d. in clothing weight was 0.3 kg for both men and women. Over the 55 °C range in the lowest to the highest outdoor temperatures, the regressions predicted a maximal change in clothing weight of only 0.4 kg in women and 0.6 kg in men. CONCLUSION: The clothing weight of men is significantly greater than that of women, but there is little variability throughout the year. Therefore, a clothing adjustment of approximately 0.8 kg for women and 1.2 kg for men is appropriate regardless of outdoor temperature.

Validity of combining heart rate and uniaxial acceleration to measure free-living physical activity energy expenditure in young men.

Combining accelerometry (ACC) with heart rate (HR) monitoring is thought to improve activity energy expenditure (AEE) estimations compared with ACC alone to evaluate the validity of ACC and HR used alone or combined. The purpose of this study was to estimate AEE in free-living conditions compared with doubly labeled water (DLW). Ten-day free-living AEE was measured by a DLW protocol in 35 18- to 55-yr-old men (11 lean active; 12 lean sedentary; 12 overweight sedentary) wearing an Actiheart (combining ACC and HR) and a RT3 accelerometer. AEE was estimated using group or individual calibration of the HR/AEE relationship, based on an exercise-tolerance test. In a subset (n = 21), AEE changes (ΔAEE) were measured after 1 mo of detraining (active subjects) or an 8-wk training (sedentary subjects). Actiheart-combined ACC/HR estimates were more accurate than estimates from HR or ACC alone. Accuracy of the Actiheart group-calibrated ACC/HR estimates was modest [intraclass correlation coefficient (ICC) = 0.62], with no bias but high root mean square error (RMSE) and limits of agreement (LOA). The mean bias of the estimates was reduced by one-third, like RMSE and LOA, by individual calibration (ICC = 0.81). Contrasting with group-calibrated estimates, the Actiheart individual-calibrated ACC/HR estimates explained 40% of the variance of the DLW-ΔAEE (ICC = 0.63). This study supports a good level of agreement between the Actiheart ACC/HR estimates and DLW-measured AEE in lean and overweight men with varying fitness levels. Individual calibration of the HR/AEE relationship is necessary for AEE estimations at an individual level rather than at group scale and for ΔAEE evaluation.

Effect of exercise on the diurnal variation in energy substrate use during a high-fat diet.

Aerobic exercise increases 24-h fat oxidation following initiation of a high-fat diet. The objective of this study is to examine the time course of increased fat oxidation under exercise and sedentary conditions. Eighteen healthy subjects completed a randomized crossover design (sedentary and exercise visits) staying for five consecutive days in a metabolic chamber each visit. On day 1, 30% of energy intake was from fat; days 2-5 had 50% of energy as fat. During exercise, subjects rode on a stationary cycle at 45% of VO2max for 1 h in the mornings and evenings. Respiratory gases and urinary nitrogen were collected to calculate macronutrient oxidation and non-protein respiratory exchange ratio (NPRER). This data, collected continuously (24-h periods), were subsequently divided into three time segments: (1) exercise + recovery (1000-1200 hours, 2100-2200 hours), (2) sleep (2300-0645 hours), and (3) wake (all remaining hours). NPRER on exercise versus sedentary visits was lower for the sleep segment (0.77 ± 0.01 01 vs. 0.81 ± 0.01, p < 0.001), higher for the exercise + recovery segment (0.88 ± 0.01 vs. 0.86 ± 0.01, p < 0.001), and was not different for the wake segment. Fat oxidation was significantly higher for exercise versus sedentary treatments during sleep (41 ± 2 vs. 31 ± 2 g), wake (62 ± 3 vs. 51 ± 3 g), and exercise + recovery segments (33 ± 3 vs.16 ± 1 g), but so was fat intake by design (171 ± 8 vs. 128 ± 7 g/d). Although exercise showed greater fat oxidation during all segments, dietary fat intake was also higher. Therefore, based on NPRER, the time of day during which the exercise treatment increased the ratio of fat to carbohydrate oxidation was during sleep.

European ancestry and resting metabolic rate in older African Americans.

BACKGROUND/OBJECTIVES: Resting metabolic rate (RMR) contributes 60-80% of total energy expenditure and is consistently lower in populations of African descent compared with populations of European populations. Determination of European ancestry (EA) through single nucleotide polymorphism (SNP) analysis would provide an initial step for identifying genetic associations that contribute to low RMR. We sought to evaluate the association between RMR and EA in African Americans. SUBJECTS/METHODS: RMR was measured by indirect calorimetry in 141 African American men and women (aged 74.7±3.0 years) enrolled in a substudy of the Health, Aging and Body Composition Study. Ancestry informative markers were used to estimate individual percent EA. Multivariate regression was used to assess the association between RMR and EA after adjustments for soft tissue fat-free mass (STFFM), fat mass, age, study site, physical activity level and sex. RESULTS: Mean EA was 23.8±16% (range: 0.1-70.7%) and there were no differences by sex. Following adjustments, each percent EA was associated with a 1.6 kcal/day (95% Confidence interval: 0.42, 2.7 kcal/day) higher RMR (P=0.008). This equates to a 160 kcal/day lower RMR in a population of completely African ancestry, with one of completely European ancestry. Additional adjustment for trunk STFFM that partially accounts for high-metabolic rate organs did not affect this association. CONCLUSIONS: EA in African Americans is strongly associated with higher RMR. The data suggest that population differences in RMR may be due to genetic variants.

Impact of exercise and dietary fatty acid composition from a high-fat diet on markers of hunger and satiety.

To compare the effects of both dietary fatty acid composition and exercise vs. sedentary conditions on circulating levels of hunger and satiety hormones. Eight healthy males were randomized in a 2 × 2 crossover design. The four treatments were 3 days of HF diets (50% of energy) containing high saturated fat (22% of energy) with exercise (SE) or sedentary (SS) conditions, and high monounsaturated fat (30% of energy) with exercise (UE) or sedentary (US) conditions. Cycling exercise was completed at 45% of VO(2)max for 2h daily. On the third HF day, 20 blood samples were drawn over a 24h period for each hormone (leptin, insulin, ghrelin, and peptide YY (PYY)). A visual analog scale (VAS) was completed hourly between 0800 and 2200. Average 24h leptin and insulin levels were lower while 24h PYY was higher during exercise vs. sedentary conditions. FA composition did not differentially affect 24h hormone values. VAS scores for hunger and fullness did not differ between any treatment but did correlate with ghrelin, leptin, and insulin. High saturated or unsaturated fat diets did not differ with respect to markers of hunger or satiety. Exercise decreased 24h leptin and insulin while increasing PYY regardless of FA composition.

Influence of dietary fatty acid composition and exercise on changes in fat oxidation from a high-fat diet.

Acute high-fat (HF) diets can lead to short-term positive fat balances until the body increases fat oxidation to match intake. The purpose of this study was to examine the effects of a HF diet, rich in either mono-unsaturated or saturated fatty acids (FAs) and exercise, on the rate at which the body adapts to a HF diet.(13)C-labeled oleate and (2)H-labeled palmitate were also given to determine the contribution of exogenous vs. global fat oxidation. Eight healthy men (age of 18-45 yr; body mass index of 22 ± 3 kg/m(2)) were randomized in a 2 × 2 crossover design. The four treatments were a high saturated fat diet with exercise (SE) or sedentary (SS) conditions and a high monounsaturated fat diet with exercise (UE) or sedentary (US) conditions. Subjects stayed for 5 days in a metabolic chamber. All meals were provided. On day 1, 30% of energy intake was from fat, whereas days 2-5 had 50% of energy as fat. Subjects exercised on a stationary cycle at 45% of maximal oxygen uptake for 2 h each day. Respiratory gases and urinary nitrogen were collected to calculate fat oxidation. Change from day 1 to day 5 showed both exercise treatments increased fat oxidation (SE: 76 ± 30 g, P = 0.001; UE: 118 ± 31 g, P < 0.001), whereas neither sedentary condition changed fat oxidation (SS: -10 ± 33 g, P = not significant; US: 41 ± 14 g, P = 0.07). No differences for dietary FA composition were found. Exercise led to a faster adaptation to a HF diet by increasing fat oxidation and achieving fat balance by day 5. Dietary FA composition did not differentially affect 24-h fat oxidation.

Prediction of fat-free mass by bioelectrical impedance analysis in older adults from developing countries: a cross-validation study using the deuterium dilution method.

OBJECTIVE: Several limitations of published bioelectrical impedance analysis (BIA) equations have been reported. The aims were to develop in a multiethnic, elderly population a new prediction equation and cross-validate it along with some published BIA equations for estimating fat-free mass using deuterium oxide dilution as the reference method. DESIGN AND SETTING: Cross-sectional study of elderly from five developing countries. METHODS: Total body water (TBW) measured by deuterium dilution was used to determine fat-free mass (FFM) in 383 subjects. Anthropometric and BIA variables were also measured. Only 377 subjects were included for the analysis, randomly divided into development and cross-validation groups after stratified by gender. Stepwise model selection was used to generate the model and Bland Altman analysis was used to test agreement. RESULTS: FFM = 2.95 - 3.89 (Gender) + 0.514 (Ht2/Z) + 0.090 (Waist) + 0.156 (Body weight). The model fit parameters were an R2, total F-Ratio, and the SEE of 0.88, 314.3, and 3.3, respectively. None of the published BIA equations met the criteria for agreement. The new BIA equation underestimated FFM by just 0.3 kg in the cross-validation sample. The mean of the difference between FFM by TBW and the new BIA equation were not significantly different; 95% of the differences were between the limits of agreement of -6.3 to 6.9 kg of FFM. There was no significant association between the mean of the differences and their averages (r= 0.008 and p= 0.2). CONCLUSIONS: This new BIA equation offers a valid option compared with some of the current published BIA equations to estimate FFM in elderly subjects from five developing countries.

Energy expenditure in young adult urban informal settlement dwellers in South Africa.

Obesity prevalences are increasing in industrialized and developing countries. As a pilot for a comparative study of physical activity and weight change, we assessed energy expenditure (EE) in young black South African adults living in an urban informal settlement. Total EE (TEE) was assessed using doubly labeled water, activity EE (AEE) and activity patterns by accelerometry and body composition by isotope dilution. Twenty young women and eight men were enrolled. Over 50% of the women and no men were obese (mean BMI 31.0 and 21.6 kg/m(2), respectively). Women had significantly lower TEE and AEE after adjustment for body size, as well as lower levels of moderate and vigorous activity. Neither TEE nor AEE was associated with BMI or percent body fat, whereas percent time in vigorous activity was modestly negatively associated with adiposity. These data add to the small literature on EE and activity among populations undergoing epidemiologic transitions.