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Background: In recent history, there have been significant increases in both soft drink consumption and the prevalence of obesity throughout the developed world. To help curb the obesity epidemic, a better understanding of the behaviors contributing to weight and fat gain is vital. Objective: To examine the extent to which soft drink consumption is predictive of changes in body composition in middle-aged women over a 4-year period, while statistically controlling for age, energy intake, physical activity, and menopause status. Design: A prospective cohort design over 48 months with no intervention. Self-reported soft drink consumption was used to predict changes in body weight and body fat percentage over the study period. Subjects included 170 healthy women (mean: 41.5 yrs at baseline). Soft drink consumption and menopause status were measured by questionnaire. Body weight was assessed using a calibrated, electronic scale, and total body fat percentage was measured using dual energy x-ray absorptiometry (DEXA). Energy intake was estimated using 7-day, weighed, food records. Results: Women who primarily consumed sugar-sweetened soft drinks gained significantly more weight than those who consumed diet soft drinks or no soft drinks (p = 0.022), even after controlling for confounding variables, except energy intake, which weakened the relationship by 28%. Changes in body fat were unrelated to the type of soft drink consumed. Women who consumed 7+ soft drinks per week gained significantly less body fat (p = 0.015) and body weight (p = 0.052) over the 4-year study compared to women who consumed fewer soft drinks per week. Further investigation revealed that women who consumed 7+ soft drinks per week did so almost exclusively in the form of diet soft drinks (87%). Conclusions: Drinking sugar-sweetened soft drinks significantly increases risk of weight gain compared to consuming diet soft drinks or no soft drinks over a 4-year period. It appears that this relationship is partly due to differences in energy intake among those who drink different types of soft drinks. Thus, it appears that consuming diet soft drinks or no soft drinks instead of sugar-sweetened soft drinks may be a worthwhile method of preventing weight gain.

The purpose of this study was to determine the validity and reliability of four methods of estimating body composition in 331 participants (177 boys, 154 girls) between 12-17 years of age. Percent body fat (%BF) was assessed once on one day using DEXA and twice using the sum of two skinfold (SF) and three bio-electrical impedance analysis (BIA) devices: OMRON hand-to-hand BIA, TANITA 521 foot-to-foot BIA, and TANITA 300A foot-to-foot BIA. The same assessments were repeated on 79 of the participants on a second day. DEXA was used as the criterion method of estimating %BF. The agreement between the estimates of %BF from the sum of two SF and the three BIA devices and DEXA was evaluated using linear regression and Bland-Altman analyses. Although the two analyses generally led to similar conclusions about each of the four prediction methods, the specific interpretations of each analysis varied because of the inherent differences in the analyses. In an attempt to determine if any of the four prediction methods were interchangeable with DEXA, the 95% confidence interval (CI) and prediction interval (PI) around the line-of-best-fit through the data are reported. The results of this study indicate that (a) all of the methods used in this study to estimate %BF were reliable within and between days, (b) the TANITA 300 BIA device performed poorly in both boys and girls and should not be used to assess body composition in children and adolescents, (c) none of the four prediction methods performed well in both boys and girls across the entire range of %BF values of the subjects in this study, (d) the sum of two SF, OMRON and TANITA 521 are acceptable for use in large population-based studies but are not recommended when the accurate assessment of body composition of an individual is critical, in which case (e) criterion methods of assessing body composition should be used.

Purpose: The purpose of this study was to assess the relationship between intensity of physical activity and body composition in 239 young adult women. Methods: This study was cross-sectional. Participants were recruited from October 2009 to December 2011 and included women from 36 different states and 6 different countries. Physical activity was objectively measured using accelerometers worn for seven days. Body composition was measured using the BOD POD. Height, weight, and circumferences were assessed. Results: Participant's mean age was 20.6±1.6 years. Their mean BMI was 22.6±3.0 kg/m2 and mean body fat percentage was 26.4±6.3 %. Average total activity counts per day were 387,560 ± 172,000, with 61.6±22.5 min per day spent in MVPA, 169.4±43 min per day in light activity, 55.6±19 min per day in moderate activity, and 6±9.2 min per day in vigorous activity. Total activity counts per day were inversely correlated with body fat (r = -0.17, p = 0.007). Light activity was positively correlated with both BMI (r = 0.17, p = 0.007) and waist circumference (r = 0.15, p = 0.0164). Moderate activity was inversely associated with body fat (r = -0.18, p = 0.0051) and hip circumference (r = -0.12, p = 0.0459). MVPA was inversely associated with body fat (r = -0.19, p = 0.0026) and hip circumference (r = -0.14, p = 0.0291). Vigorous physical activity was inversely related to body fat (r = -0.20, p = 0.0023). Using stepwise regression, the best predictor of body fat was time spent in vigorous PA (F = 9.45, p = 0.0024). The best predictor of BMI was light activity per day, which was positively correlated with BMI (F = 7.5, p = 0.0066) followed by moderate activity per day which was negatively correlated (F = 4.25, p = 0.0403). Young adult women who spent no time performing vigorous PA had significantly higher body fat percentages than women who performed some vigorous PA. Young adult women who spent less than 30 minutes per day in MVPA had significantly higher body fat percentages and BMIs than those who obtained more than 30 minutes per day. For every 10 minutes spent in MVPA per day, the odds of being obese by body fat decreased by 33%. Conclusion: Vigorous PA and MVPA appear to be the most important aspects of PA associated with lower body fat and BMI levels. Young adult women should be encouraged to obtain at least 30 minutes of MVPA per day.

The success of performance in basketball may rely on both optimal body composition and nutrient intake. To our knowledge this is the first study to examine dietary intake adequacy and season-long effects on body composition and metabolism. The purpose of this study was to examine seasonal changes in body composition (BC), resting metabolic rate (RMR) and respiratory quotient (RQ), while also examining the dietary intake adequacy of NCAA DI male basketball players. BC, RMR and RQ were assessed during pre-season, in-season, and post-season (September, December, and March), while dietary assessment was collected in September and February. Results of this study indicated that players consumed inadequate amounts of energy (ppp< 0.0001) relative to the recommendations for exercising individuals during the October baseline period. However, following analysis and consultations, athletes increased intake and received adequate amounts of energy and protein during follow-up, yet carbohydrate (p=0.0025) was still significantly lower. Results also revealed that there was a decrease in percent body fat (%BF) during season, an increase in Lean Body Mass from preseason to postseason, a peak in RMR during season and an increase in RQ post season. These findings indicate that significant metabolic and body composition changes occur in players over the season and suggest nutritional strategies employed concomitantly may be beneficial.

Background: In recent years several state high school athletic association have investigated methods to ensure the health and safety of high school wrestlers. One method implemented by the National Collegiate Athletic Association requires the prediction of minimum weight (MW) prior to the competition season. This weight certification program requires the assessment of body composition and hydration status. Results from those assessments place wrestlers in their lowest allowable wrestling weight class. There are a variety of measurement devises that have proven to be effective in measuring body composition. However, several considerations must be taken into account when choosing a devise such as affordability and reliability. Of those devices leg-to-leg bioelectrical impedance analysis (BIA) has been suggested for use with wrestlers. Purpose: To test the validity of bioelectrical impedance as an instrument of body composition and minimum wrestling weight compared to three-site skinfold using the Lohman-Brozek formula and the Bod Pod®; among hydrated high school wrestlers. Methods: Criterion for this study was the Bod Pod®. Subjects included 98 high school wrestlers taking part in the pre-season wrestling weight certification program implemented by the Virginia High School League. Hydration was assessed and a urine specific gravity (USG) ≤ 1.020 was assigned as the level of hydration. Results: In order to investigate the validity of BIA in this study a repeated measure ANOVA with between-subjects factors was used to assess the equality of means between the three measurement devices. Also, in order to investigate hydration affect subjects were divided into two categories (hydrated and dehydrated). Finally, prior to analysis subjects were placed in weight categories based on their assigned wrestling weight class. Results of this study demonstrated that the three measurement devices did not produce similar results and it was concluded that hydration level had no affect on the measurements. Therefore, at this time BIA should not be considered as an alternative method for assessing body composition in high school wrestling weight certification programs. / Ph. D.

A pig model of childhood obesity was used to study the effects of dietary energy on body adiposity, and blood parameters associated with impaired glucose clearance. Prepubertal female pigs weaned at 21 d of age were fed control (CON), refined sugar (SUG), fat (FAT), and sugar-fat (SUGFAT) diets in a completely randomized arrangement for 16 wk. Calories from fat were 8.9% for CON, 5.6% for SUG, 35.5% for FAT and 32.3% for SUGFAT. Calories from sugar were 36.0% for SUG and 30.7% for SUGFAT. Adding fat, sugar or both to diets increased (P < 0.003) calorie intake. Percentage body fat was higher (P < 0.0001) in all treatments compared to CON, and in SUGFAT and FAT compared to SUG. Ultrasound back fat depth was positively correlated (r2 = 0.909; P < 0.001) with percentage body fat and negatively (r = 0.912; P-value ) with percentage body protein. Area under the curve (AUC) in response to oral glucose tolerance at 14 wk was higher (P < 0.03) in FAT (+14.6%) and SUGFAT (+25.5%) pigs compared to CON. Glucose AUC from sugar-fed pigs was not different (P = 0.2) from fat alone-fed pigs. Adding sugar, fat, or their combination to diets increased (P < 0.008) blood glucose and decreased (P < 0.0009) plasma insulin AUC. These data show that inclusion of fat and refined sugar in pig diets increases body adiposity and impairs glucose homeostasis and suggests that the composition of calories consumed may have different effects than simply consumption of excess of calories. / Master of Science

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