Field assessments for obesity prevention in children and adults: physical activity, fitness, and body composition.

Nutrition and health educators work in community settings implementing lifestyle programs focused on obesity prevention and chronic disease risk reduction. These programs typically focus on improving diet and physical activity (PA) behaviors. Many nutrition educators may not be confident in their ability to select, administer, and interpret PA assessments to effectively evaluate their PA or lifestyle programs. This report will assist educators in identifying and selecting appropriate field-based assessments for measurement of PA, physical fitness, and body composition for children and adults. Specific guidelines, references, and resources are given for selecting assessment methods and test within these 3 areas.

Evaluation of personal and built environment attributes to physical activity: a multilevel analysis on multiple population-based data sources.

Background. Studies have documented that built environment factors potentially promote or impede leisure time physical activity (LTPA). This study explored the relationship between multiple built environment factors and individual characteristics on LTPA. Methods. Multiple data sources were utilized including individual level data for health behaviors and health status from the Nevada Behavioral Risk Factor Surveillance System (BRFSS) and community level data from different data sources including indicators for recreation facilities, safety, air quality, commute time, urbanization, population density, and land mix level. Mixed model logistic regression and geographic information system (GIS) spatial analysis were conducted. Results. Among 6,311 respondents, 24.4% reported no LTPA engagement during the past 30 days. No engagement in LTPA was significantly associated with (1) individual factors: older age, less education, lower income, being obesity, and low life satisfaction and (2) community factors: more commute time, higher crime rate, urban residence, higher population density, but not for density and distance to recreation facilities, air quality, and land mix. Conclusions. Multiple data systems including complex population survey and spatial analysis are valuable tools on health and built environment studies.

Hand-held indirect calorimeter offers advantages compared with prediction equations, in a group of overweight women, to determine resting energy expenditures and estimated total energy expenditures during research screening.

OBJECTIVE: To compare standardized prediction equations to a hand-held indirect calorimeter in estimating resting energy and total energy requirements in overweight women. DESIGN: Resting energy expenditure (REE) was measured by hand-held indirect calorimeter and calculated by prediction equations Harris-Benedict, Mifflin-St Jeor, World Health Organization/Food and Agriculture Organization/United Nations University (WHO), and Dietary Reference Intakes (DRI). Physical activity level, assessed by questionnaire, was used to estimate total energy expenditure (TEE). SUBJECTS: Subjects (n=39) were female nonsmokers older than 25 years of age with body mass index more than 25. STATISTICAL ANALYSES: Repeated measures analysis of variance, Bland-Altman plot, and fitted regression line of difference. A difference within +/-10% of two methods indicated agreement. RESULTS: Significant proportional bias was present between hand-held indirect calorimeter and prediction equations for REE and TEE (P<0.01); prediction equations overestimated at lower values and underestimated at higher values. Mean differences (+/-standard error) for REE and TEE between hand-held indirect calorimeter and Harris-Benedict were -5.98+/-46.7 kcal/day (P=0.90) and 21.40+/-75.7 kcal/day (P=0.78); between hand-held indirect calorimeter and Mifflin-St Jeor were 69.93+/-46.7 kcal/day (P=0.14) and 116.44+/-75.9 kcal/day (P=0.13); between hand-held indirect calorimeter and WHO were -22.03+/-48.4 kcal/day (P=0.65) and -15.8+/-77.9 kcal/day (P=0.84); and between hand-held indirect calorimeter and DRI were 39.65+/-47.4 kcal/day (P=0.41) and 56.36+/-85.5 kcal/day (P=0.51). Less than 50% of predictive equation values were within +/-10% of hand-held indirect calorimeter values, indicating poor agreement. CONCLUSIONS: A significant discrepancy between predicted and measured energy expenditure was observed. Further evaluation of hand-held indirect calorimeter research screening is needed.

Glucose and insulin responses to whole grain breakfasts varying in soluble fiber, beta-glucan: a dose response study in obese women with increased risk for insulin resistance.

BACKGROUND: A high intake of whole grains containing soluble fiber has been shown to lower glucose and insulin responses in overweight humans and humans with type 2 diabetes. AIM OF THE STUDY: We investigated the linearity of this response after consumption of 5 breakfast cereal test meals containing wheat and/or barley to provide varying amounts of soluble fiber, beta-glucan (0, 2.5, 5, 7.5 and 10 g). METHODS: Seventeen normoglycemic, obese women at increased risk for insulin resistance consumed 5 test meals within a randomized cross-over design after consuming controlled diets for 2 days. Blood samples for glucose and insulin response were obtained prior to and 30, 60, 120 and 180 min after consuming the test meals. RESULTS: Consumption of 10 g of beta-glucan significantly reduced peak glucose response at 30 min and delayed the rate of glucose response. Area under the curve for 2 h-postprandial glycemic response was not affected by beta-glucan content. However, peak and area under the curve of insulin responses were significantly affected by the beta-glucan amount in an inverse linear relationship. CONCLUSION: These data suggest that acute consumption of 10 g of beta-glucan is able to induce physiologically beneficial effects on postprandial insulin responses in obese women at risk for insulin resistance.

Estimates of adherence and error analysis of physical activity data collected via accelerometry in a large study of free-living adults.

BACKGROUND: Activity monitors (AM) are small, electronic devices used to quantify the amount and intensity of physical activity (PA). Unfortunately, it has been demonstrated that data loss that occurs when AMs are not worn by subjects (removals during sleeping and waking hours) tend to result in biased estimates of PA and total energy expenditure (TEE). No study has reported the degree of data loss in a large study of adults, and/or the degree to which the estimates of PA and TEE are affected. Also, no study in adults has proposed a methodology to minimize the effects of AM removals. METHODS: Adherence estimates were generated from a pool of 524 women and men that wore AMs for 13 - 15 consecutive days. To simulate the effect of data loss due to AM removal, a reference dataset was first compiled from a subset consisting of 35 highly adherent subjects (24 HR; minimum of 20 hrs/day for seven consecutive days). AM removals were then simulated during sleep and between one and ten waking hours using this 24 HR dataset. Differences in the mean values for PA and TEE between the 24 HR reference dataset and the different simulations were compared using paired t-tests and/or coefficients of variation. RESULTS: The estimated average adherence of the pool of 524 subjects was 15.8 +/- 3.4 hrs/day for approximately 11.7 +/- 2.0 days. Simulated data loss due to AM removals during sleeping hours in the 24 HR database (n = 35), resulted in biased estimates of PA (p < 0.05), but not TEE. Losing as little as one hour of data from the 24 HR dataset during waking hours results in significant biases (p < 0.0001) and variability (coefficients of variation between 7 and 21%) in the estimates of PA. Inserting a constant value for sleep and imputing estimates for missing data during waking hours significantly improved the estimates of PA. CONCLUSION: Although estimated adherence was good, measurements of PA can be improved by relatively simple imputation of missing AM data.

A controlled trial of reduced meal frequency without caloric restriction in healthy, normal-weight, middle-aged adults.

BACKGROUND: Although consumption of 3 meals/d is the most common pattern of eating in industrialized countries, a scientific rationale for this meal frequency with respect to optimal health is lacking. A diet with less meal frequency can improve the health and extend the lifespan of laboratory animals, but its effect on humans has never been tested. OBJECTIVE: A pilot study was conducted to establish the effects of a reduced-meal-frequency diet on health indicators in healthy, normal-weight adults. DESIGN: The study was a randomized crossover design with two 8-wk treatment periods. During the treatment periods, subjects consumed all of the calories needed for weight maintenance in either 3 meals/d or 1 meal/d. RESULTS: Subjects who completed the study maintained their body weight within 2 kg of their initial weight throughout the 6-mo period. There were no significant effects of meal frequency on heart rate, body temperature, or most of the blood variables measured. However, when consuming 1 meal/d, subjects had a significant increase in hunger; a significant modification of body composition, including reductions in fat mass; significant increases in blood pressure and in total, LDL-, and HDL-cholesterol concentrations; and a significant decrease in concentrations of cortisol. CONCLUSIONS: Normal-weight subjects are able to comply with a 1 meal/d diet. When meal frequency is decreased without a reduction in overall calorie intake, modest changes occur in body composition, some cardiovascular disease risk factors, and hematologic variables. Diurnal variations may affect outcomes.

Watermelon consumption increases plasma arginine concentrations in adults.

OBJECTIVE: Watermelon is a rich source of citrulline, an amino acid that can be metabolized to arginine, a conditionally essential amino acid for humans. Arginine is the nitrogenous substrate used in the synthesis of nitric oxide and plays an essential role in cardiovascular and immune functions. No detailed studies have been conducted to evaluate plasma arginine response in humans after long-term feeding of citrulline from natural plant sources. This study investigated if watermelon juice consumption increases fasting concentrations of plasma arginine, ornithine, and citrulline in healthy adult humans. METHODS: Subjects (n = 12-23/treatment) consumed a controlled diet and 0 (control), 780, or 1560 g of watermelon juice per day for 3 wk in a crossover design. The treatments provided 1 and 2 g of citrulline per day. Treatment periods were preceded by washout periods of 2 to 4 wk. RESULTS: Compared with the baseline, fasting plasma arginine concentrations increased 12% after 3 wk of the lower-dose watermelon treatment; arginine and ornithine concentrations increased 22% and 18%, respectively, after 3 wk of the higher-dose watermelon treatment. Fasting citrulline concentrations did not increase relative to the control but remained stable throughout the study. CONCLUSION: The increased fasting plasma concentrations of arginine and ornithine and stable concentrations of plasma citrulline in response to watermelon juice consumption indicated that the citrulline from this plant origin was effectively converted into arginine. These results demonstrate that plasma concentration of arginine can be increased through intake of citrulline from watermelon.

Low plasma retinol concentrations increase the risk of developing bronchopulmonary dysplasia and long-term respiratory disability in very-low-birth-weight infants.

BACKGROUND: The effect of inadequate vitamin A during the neonatal period on lung status is still unknown. OBJECTIVE: We tested the hypothesis that low plasma retinol concentrations during the first month of life are independently associated with bronchopulmonary dysplasia (BPD) and long-term respiratory morbidity at 6 mo gestationally corrected age (ie, the age the infant would be had the pregnancy gone to term). DESIGN: Respiratory outcome information was obtained to 6 mo corrected age for a historical cohort of very-low-birth-weight neonates (<1250 g) who were admitted to intensive care over a 7-y period. Neonates with one or more plasma measurements of retinol concentrations < 0.35 micromol/L (<100 microg/L) on days 1-28 were classified as having low vitamin A. BPD was defined at day 28 by clinical and radiologic criteria and by use of supplemental oxygen at 36 wk postmenstrual age (PMA). Dependence on supplemental oxygen was used to identify long-term respiratory disability at 6 mo corrected age. Multivariate logistic regression analyses were conducted. RESULTS: Of the 350 study infants, 192 (55%) had low vitamin A status. BPD occurred in 52% of survivors at day 28 (173/331) and at 36 wk PMA (147/285). Fourteen percent (33/244) required oxygen support at 6 mo corrected age. Adjusted odds ratios of BPD with low vitamin A were 3.5 (95% CI: 1.7, 7.2) at day 28 and 1.7 (1.0, 2.7) at 36 wk PMA. At 6 mo corrected age, the adjusted odds ratio was 2.6 (1.1, 6.4) for respiratory disability with low vitamin A. CONCLUSION: Poor vitamin A status during the first month of life significantly increased the risk of developing BPD and long-term respiratory disability.