Nutrition and Physical Activity Program to Attenuate Obesity and Promote Physical and Metabolic Fitness in Elementary School Children

Obesity and low levels of physical and metabolic fitness are risk factors for cardiovascular disease and diabetes. The purpose of this investigation was to attenuate obesity and improve physical and metabolic fitness in elementary school children. Schools have the opportunity, mechanisms, and personnel in place to deliver nutrition education, fitness activities, and a school food service that is nutritious and healthy. Cohorts from grades 3 to 5 in two school districts in rural Nebraska (Intervention/Control) participated in a 2-year study of physical activity and modified school lunch program. Data collection for aerobic capacity, body composition, blood chemistry, nutrition knowledge, energy intake, and physical activity was at the beginning and end of each year. Int received enhanced physical activity, grade specific nutrition education, and a lower fat and sodium school lunch program. Con continued with a regular school lunch and team sports activity program. At year 2, Int lunches had significantly less energy (9%), fat (25%), sodium (21%), and more fiber (17%). However, measures of 24-hour energy intake for Int and Con showed significant differences for sodium only. Physical activity in the classroom was 6% greater for Int compared to Con (p < 0.05) but physical activity outside of school was ?16 % less for Int compared to Con (p < 0.05). Body weight and body fat were not different between schools for normal weight or obese children. No differences were found for cholesterol, insulin, and glucose; however, HDL cholesterol was significantly greater and cholesterol/HDL was significantly less for Int compared to Con (p < 0.05). It appears that compensation in both energy intake and physical activity outside of school may be responsible for the lack of differences between Int and Con.     

Obesity Is Associated With Altered Lung Function Independently of Physical Activity and Fitness

Measures of obesity, especially central adiposity, have been associated with reduced lung function. However, previous studies may have been affected by confounding by physical activity and fitness. This study aimed to examine the relationship among body fatness, fat distribution, and lung function, adjusted for physical activity energy expenditure (PAEE) and aerobic fitness (VO₂max), in a cohort of British white adults with a family history of type 2 diabetes. A total of 320 adults (mean age 40.4 ± 6.0 years) attended for anthropometric and VO₂max testing, and had ambulatory heart rate monitoring for 4 days to determine PAEE. Spirometry was used to measure forced expiratory volume in 1 s (FEV₁) and forced vital capacity (FVC). The tests were repeated 12 months later, and a cross‐sectional analysis using linear regression with repeated measures was performed. Measures of obesity (BMI, waist circumference (WC), fat mass (FM), body fat percentage (BF%)) were associated with lower lung function in men and women (P < 0.01), while waist‐to‐hip ratio (WHR) was associated with lower lung function in men only (P < 0.001). Associations remained after adjusting for age, smoking status, height, PAEE, and VO₂max. The estimated difference in mean FEV₁ and FVC per unit increase in the exposure measures were consistently stronger in men compared to women (P for interaction <0.001). Obesity is inversely associated with lung function in adults, but central fat distribution appears to have a stronger relationship with respiratory mechanics in men than in women. These associations were independent of the degree of physical activity and aerobic fitness in this cohort.     

Physical Fitness and Physical Activity in Obese and Nonobese Flemish Youth

Objective: To assess different aspects of physical fitness and physical activity in obese and nonobese Flemish youth. Research Methods and Procedures: A random sample of 3214 Flemish schoolchildren was selected and divided into an “obese” and “nonobese” group based on body mass index and sum of skinfolds. Physical fitness was assessed by the European physical fitness test battery. Physical activity was estimated by a modified version of the Baecke Questionnaire. Results: Obese subjects had inferior performances on all tests requiring propulsion or lifting of the body mass (standing‐broad jump, sit‐ups, bent‐arm hang, speed shuttle run, and endurance shuttle run) compared with their nonobese counterparts (p < 0.001). In contrast, the obese subjects showed greater strength on handgrip (p < 0.001). Both groups had similar levels of leisure‐time physical activity; however, nonobese boys had a higher sport index than their obese counterparts (p < 0.05). Discussion: Results of this study show that obese subjects had poorer performances on weight‐bearing tasks, but did not have lower scores on all fitness components. To encourage adherence to physical activity in obese youth, it is important that activities are tailored to their capabilities. Results suggest that weight‐bearing activities should be limited at the start of an intervention with obese participants and alternative activities that rely more on static strength used.     

Resting Metabolic Rate in African-American and Caucasian Girls

YANOVSKI, SUSAN ZELITCH, JAMES C REYNOLDS, ALLISON J BOYLE, JACK A YANOVSKI. Resting metabolic rate in African-American and Caucasian girls. Recent studies have found a lower resting metabolic rate (RMR) in African-American (AA) women with obesity as compared with Caucasian (C) women with obesity. It is unknown if this difference in RMR is seen in prepubertal girls or in those of average body weight. Therefore, we studied RMR in 21 AA and 24 C girls, ages 7–10, who were well matched for age, weight, body mass index (BMI), and pubertal status. All had BMI between 15% and 85% for age and race, based on data from the First National Health and Nutrition Examination Survey. Fat free mass (FFM) was measured by dual-energy X-ray absorptiometry. RMR was measured with a Deltatrac indirect calorimeter under controlled conditions after the subjects underwent an overnight fast. The slopes of the regression equations were similar for both groups (ρ=0.7). After adjustment for FEM, the AA girls had a significantly lower RMR than did the C girls (?92 ± 32 kcal/d, ρ=0.007 by analysis of covariance). This significance was maintained after exclusion of total body bone mineral content. These data suggest that normal-weight prepubertal AA girls may have reduced resting energy expenditure compared with C girls.     

Racial Differences in Insulin Secretion and Sensitivity in Prepubertal Children: Role of Physical Fitness and Physical Activity

Objective: To investigate in prepubertal children whether physical fitness and/or physical activity are: 1) associated with insulin secretion and sensitivity and 2) account for racial differences in insulin secretion and sensitivity. Research Methods and Procedures: Subjects included 34 African American and 34 white nondiabetic children aged 5 to 11 years. Data were divided into two sets according to the availability of VO_2max and physical activity data. Body composition was measured by dual‐energy X‐ray absorptiometry. Subcutaneous abdominal adipose tissue and intra‐abdominal adipose tissue were examined by computed tomography. Insulin sensitivity (S_I) and acute insulin response (AIR) were determined by a frequently sampled intravenous glucose tolerance test. An all‐out, progressive treadmill exercise test was used for measuring VO_2max. Physical activity data were collected by questionnaire. Results: African American children had lower S_I and higher AIR than white children, after adjusting for total body fat mass. African Americans reported higher levels of physical activity (hours/wk) than whites, but had a lower VO_2max. In multiple linear regression analysis, hours/wk of activity and hours/wk of vigorous activity, but not moderate activity, were independently related to S_I and AIR after adjusting for race, total body fat mass or fat distribution, and total lean tissue mass. VO_2max was not related to AIR, and was inversely related to S_I, after adjusting for body composition. Race remained significantly associated with both S_I and AIR, even after adjusting for body composition, fat distribution, and hours/wk of activity or hours/wk of vigorous activity. Discussion: In summary, overall physical activity and, especially, vigorous activity were associated with insulin secretion and sensitivity. However, neither physical activity nor VO_2max explained the racial difference in insulin secretion (higher in African Americans) and sensitivity (lower in African Americans). Thus, racial (African American to white) differences in aspects of insulin action seem to be due to factors other than body composition, fat distribution, cardiovascular fitness, and amount of physical activity.     

Evaluation of Metabolic Risk in Prepubertal Girls Versus Boys in Relation to Fitness and Physical Activity

BackgroundLow levels of cardiorespiratory fitness (CRF) and physical activity (PA) are associated with a risk of the development of metabolic syndrome. Contradictory findings are reported in the literature regarding the influence of sex and CRF and PA on metabolic changes.ObjectiveThe aim of this study was to analyze the effects of CRF and PA on lipid and carbohydrate metabolism biomarkers in boys and girls.MethodsA total of 82 prepubertal boys and 55 girls (7–12 years of age) were classified according to sex, low or high CRF, and performance or nonperformance of PA. Anthropometric and blood pressure (BP) measurements, plasma lipid profile values, glucose and insulin levels, and homeostasis model assessment for insulin resistance were analyzed.ResultsThe percentage of boys with high CRF and performance of PA was higher than that of girls (P < 0.05). When children of the same sex were compared, higher values for body mass index and waist circumference z-scores were found for boys with low CRF compared with boys with high CRF (P < 0.001) without differences between girls, and in all groups classified by PA. Systolic and diastolic BPs were higher in boys than in girls, in both CRF and PA groups (P < 0.05). In the low CRF and no PA groups, girls had higher plasma glucose, total cholesterol, and low-density lipoprotein cholesterol levels than boys, with higher high-density lipoprotein cholesterol and apolipoprotein A levels (P < 0.05).ConclusionsSex in relation to CRF and PA could affect the plasma lipid profile. These changes in girls are associated with low CRF and low levels of PA. Considering these results, we suggest the need to improve CRF and promote PA, especially in girls, to reduce metabolic risk.     

Insulin Sensitivity,Cardiorespiratory Fitness,and Physical Activity in Overweight Hispanic Youth

Objective: To determine whether cardiorespiratory fitness and/or physical activity (PA) were related to measures of insulin sensitivity and secretion independent of body composition in overweight Hispanic children. Research Methods and Procedures: Ninety‐five Hispanic children (n = 55 boys; n = 40 girls; 8 to 13 years old) participated in this investigation. The frequently sampled intravenous glucose tolerance test was used to determine the insulin sensitivity index (SI), the acute insulin response, and the disposition index. Cardiorespiratory fitness [maximal oxygen uptake (Vo_2max)] was evaluated using a treadmill protocol, and PA was determined by an interviewer‐administered questionnaire. Body composition was measured using DXA. Results: Unadjusted correlations indicated that Vo_2max (milliliters of O₂ per minute) was negatively related to SI (r = ?0.46, p < 0.05) and disposition index (r = ?0.31, p < 0.05) and positively associated with fasting insulin (r = 0.29, p < 0.05), but these relationships were no longer significant once gender, Tanner stage, fat mass, and soft lean tissue mass were included as covariates (all p > 0.05). Multivariate linear regression analysis showed that body fat mass explained 53% of the variance in SI and that Vo_2max (milliliters of O₂ per minute) was not independently related to SI. Cardiorespiratory fitness was positively related to both fat mass (r = 0.43, p < 0.001) and soft lean tissue mass (r = 0.89, p < 0.001). PA was not related to any measure of insulin sensitivity and secretion. Discussion: Cardiorespiratory fitness, as determined by Vo_2max (milliliters of O₂ per minute), was not independently related to insulin sensitivity or secretion, suggesting that Vo_2max influences insulin dynamics indirectly through fat mass.     

Physical Training Improves Body Composition of Black Obese 7- to 11-Year-Old Girls

We determined the effect of supervised physical training, without dietary intervention, on body composition of obese girls. The subjects were 25 obese 7-to 11-year-old black girls, divided into physical training and lifestyle education groups which were comparable on baseline body composition; 22 girls finished all aspects of the study. Twelve girls engaged in aerobic training (10 weeks, 5 days/week) while 10 engaged in weekly lifestyle discussions without formal physical training. Total body and regional body composition were measured with dual energy x-ray absorptiometry, skin folds and circumferences. Aerobic fitness was measured by heart rate response to sub maximal treadmill exercise. The physical training group attended 94% of scheduled sessions and kept their heart rates at an average of 163 bpm for 28 minutes/session. The lifestyle group attended 95% of their sessions; they remained stable in aerobic fitness and most body composition measurements. The physical training group showed a significant improvement in aerobic fitness and a significant decline of 1.4% body fat. Skin fold and circumference indices of fatness also declined significantly in physical training, without dietary intervention, improved the fitness and body composition of obese black girls.     

Weight‐Bearing Physical Activity among Girls and Mothers: Relationships to Girls’ Weight Status

Objective: To assess weight‐bearing physical activity (WBPA) barriers, benefits, self‐efficacy, social influence, and behaviors [WBPA and physical activity (PA)] among girls and their mothers according to girls’ weight status (nonoverweight vs. overweight). Research Methods and Procedures: Participants were 9‐ to 11‐year‐old girls (n = 295) and their mothers who participated in the baseline assessment of a nutrition and PA intervention trial. Girls’ and mothers’ WBPA attitudes and mothers’ WBPA behaviors were self‐reported on questionnaires. Girls’ WBPA and total PA behaviors were self‐reported using a structured interview (Physical Activity Checklist Interview). Stature and weight were measured by standardized anthropometrics. Overweight status was based on BMI. Results: Compared with nonoverweight girls, overweight girls were significantly more likely to report barriers to WBPA participation and perceive social influence from family and friends to do more WBPA. They were also significantly less likely to report self‐efficacy regarding WBPA and to believe that they did enough WBPA. Compared with mothers of nonoverweight girls, mothers of overweight girls were significantly more likely to report that it is difficult to persuade their daughters to do more WBPA and significantly less likely to report that WBPA was fun for their daughters. Girls’ overweight status was not associated with girls’ reports of minutes spent per week in PA or WBPA. Discussion: The present study's findings of lower WBPA self‐efficacy, lack of enjoyment of WBPA, and higher perceived social influence to do WBPA among overweight girls suggest that efforts are needed to promote physical competencies and positive perceptions of PA among overweight girls.     

Fatness and Physical Fitness of Girls 7 to 17 Years

A two-fold approach was used to investigate the association between fatness and fitness of girls 7 to 17 years of age: first, age-specific correlations between fatness and measures of health-related and motor fitness, and second, comparisons of fitness levels of girls classified as fat and lean. A representative sample of 6700 between 7 to 17 years was surveyed. Adiposity (fatness) was estimated as the sum of five skinfolds (biceps, triceps, subscapular, suprailiac, medial calf). Physical fitness included health-related items (step test, PWC₁₇₀ the sit and reach, sit-ups and leg lifts, flexed arm hang) and motor performance items (standing long jump, vertical jump, arm pull strength, flamingo stand, shuttle run, plate tapping). Age-specific partial correlations between fatness and each fitness item, controlling for stature and weight, were calculated. In addition, in each age group the fattest 5% (presumably the obese) and the leanest 5% were compared on each fitness test. After controlling for stature and weight, subcutaneous fatness accounts for variable percentages of the variance in each fitness item. Estimates for health-related fitness items are: cardiorespiratory endurance - step test (3% to 5%) and PWC₁₇₀ (0% to 16%), flexibility - sit and reach (3% to 8%), functional strength - flexed arm hang (6% to 17%) and abdominal strength - sit-ups/leg lifts (1% to 8%). Corresponding estimates for motor fitness items are more variable: speed of limb movement -plate tapping (0% to 3%), balance - flamingo stand (0% to 5%), speed and agility - shuttle run (2% to 12 %), static strength - arm pull (4% to 12%), explosive strength - standing long jump/vertical jump (11% to 18%). At the extremes, the fattest girls have generally poorer levels of health-related and motor fitness.     

BMI,Physical Activity,and Health Care Utilization/Costs among Medicare Retirees

Objective: To examine the influence of physical activity (PA) and BMI on health care utilization and costs among Medicare retirees. Research Methods and Procedures: This cross‐sectional study was based on 42, 520 Medicare retirees in a U.S.‐wide manufacturing corporation who participated in indemnity/perferred provider and one health risk appraisal during the years 2001 and 2002. Participants were assigned into one of the three weight groups: normal weight, overweight, and obese. PA behavior was classified into three levels: sedentary (0 time/wk), moderately active (1 to 3 times/wk), and very active (4+ times/wk). Results: Generalized linear models revealed that the moderately active retirees had $1456, $1731, and $1177 lower total health care charges than their sedentary counterparts in the normal‐weight, overweight, and obese groups, respectively (p < 0.01). The very active retirees had $1823, $581, and $1379 lower costs than the moderately active retirees. Health care utilization and specific costs showed similar trends with PA levels for all BMI groups. The total health care charges were lower with higher PA level for all age groups (p < 0.01). Discussion: Regular PA has strong dose‐response effects on both health care utilization and costs for overweight/obese as well as normal‐weight people. Promoting active lifestyle in this Medicare population, especially overweight and obese groups, could potentially improve their well‐being and save a substantial amount of health care expenditures. Because those Medicare retirees are hard to reach in general, more creative approaches should be launched to address their needs and interests as well as help reduce the usage of health care system.     

Stability of the Association between Birth Weight and Childhood Overweight during the Development of the Obesity Epidemic

Objective: To assess whether changes in the birth weight distribution or changes in the association of birth weight with the later risk of childhood overweight have contributed to the development of the obesity epidemic. Research Methods and Procedures: A Danish population‐based cohort study of 124,615 girls and 128,346 boys (ages 6 to 13 years), born between 1936 and 1983, were studied. Birth weight and annual measurements of height and weight were obtained from school health records. Overweight was defined by BMI in relation to internationally accepted criteria. The relative risk of being overweight by birth weight was calculated separately for each age, sex, and time period. Results: The birth weight distribution remained relatively stable over time. Compared with children with a birth weight of 3.0 to 3.5 kg, the risk of overweight increased consistently with each increase in birth weight category among girls and boys and at all ages between 6 and 13 years. Furthermore, the association between birth weight and increased risk of overweight in childhood remained stable across a 48‐year period. Discussion: The increase in the prevalence of overweight could not be explained by time trends in the distribution of birth weight or by changes in the association between birth weight and the later risk of overweight over time. This implies that, unless the prenatal environment influences the later risk of overweight without increasing birth weight, the environmental influences contributing to the obesity epidemic in children of school age operate in the early postnatal period.     

Physical activity correlates in adolescent girls who differ by weight status

Objective: This study compared correlates of physical activity (PA) among African‐American and white girls of different weight groups to guide future interventions. Research Methods and Procedures: Participants were 1015 girls (mean age, 14.6 years; 45% African‐American) from 12 high schools in South Carolina who served as control subjects for a school‐based intervention. Post‐intervention measures obtained at the end of ninth grade were used. PA was measured using the Three‐Day PA Recall, and a questionnaire measured social‐cognitive and environmental variables thought to mediate PA. Height and weight were measured, and BMI was calculated. Girls were stratified by race and categorized into three groups, based on BMI percentiles for girls from CDC growth charts: normal (BMI < 85th percentile), at risk (BMI, 85th to 94th percentile), and overweight (BMI ≥ 95th percentile). Girls were further divided into active and low‐active groups, based on a vigorous PA standard (average of one or more 30‐minute blocks per day per 3‐day period). Mixed‐model ANOVA was used to compare factors among groups, treating school as a random effect Results: None of the social‐cognitive or environmental variables differed by weight status for African‐American or white girls. Perceived behavioral control and sports team participation were significantly higher in girls who were more active, regardless of weight or race group. In general, social‐cognitive variables seem to be more related to activity in white girls, whereas environmental factors seem more related to activity in African‐American girls. Discussion: PA interventions should be tailored to the unique needs of girls based on PA levels and race, rather than on weight status alone.     

Physical Activity,Obesity, and Cardiovascular Risk Factors in Children. The Belgian Luxembourg Child Study II

GUILLAUME, MICHÈLE, LEIF LAPIDUS, PER BJÖRNTORP, ANDRE LAMBERT. Physical activity, obesity, and cardiovascular risk factors in children. The Belgian Luxembourg Child Study II. Physical activity was measured in relation to cardiovascular (CV) risk factors in a randomly selected population of 1028 children from Province de Luxembourg in Belgium, a mainly rural area with a high prevalence of such risk factors among adults and children. Physical activity was estimated as participation in sport activities, a major indicator of leisure-time physical activity in schoolchildren, and physical inactivity was estimated as frequency and duration of television (TV) watching. Boys participated more frequently in sport activities than girls did (p=0. 001). A majority of the children watched TV daily. After age adjustment, bodyweight (girls, p<0. 012; boys, p<0. 027) and, in boys, body mass index (BMI) (p<0. 039) were related to days per week of TV watching. No significant relationships with other CV risk factors remained after adjustments for BMI. In analyses of independent contributions of age, TV watching, and sports activity on CV risk factors, age showed highly significant relationships. In boys, TV showed relationships with BMI (P<0. 04) and (borderline) with systolic blood pressure, independent of age and sports activity, whereas the latter was significantly related to subscapular skinfold (p<0. 04) and (borderline) with triceps skinfold and cholesterol. In girls, no significant independent contributions to risk factor associations were found. The father's education was directly associated with sports activities, whereas the mother being a housewife showed negative relationships to physical activity and positive to TV watching in their children, suggesting socioeconomic influence on the activity patterns of children. Furthermore, registrations suggested less physical activity in the most rural part of the area. It is concluded that children in this mainly rural area watch TV frequently. In boys, physical inactivity, measured both as TV watching and as registrations of sports activities, contributes independently to body fat mass. In girls, no contribution or weaker contributions of physical inactivity were found. This suggests that contributory factors leading to obesity might be different in girls and boys.     

Physical activity compliance: differences between overweight/obese and normal-weight adults

Objectives: Comparisons of physical activity measured by accelerometers in overweight/obese adults and their normal‐weight counterparts are limited. Compliance with the 2002 Institute of Medicine (IOM) exercise recommendations for 60 minutes of moderate‐intensity exercise daily has not been reported. The purpose of this study was to compare physical activity, as measured by accelerometers, in overweight/obese adults vs. normal‐weight controls and to assess compliance with recommendations for physical activity by the IOM in 2002 and by the Centers for Disease Control and Prevention and American College of Sports Medicine in 1995 for 30 minutes of moderate‐intensity activity, preferably all days of the week. Research Methods and Procedures: Sixty‐two overweight/obese subjects, BMI ≥ 25, included 31 adults, 12 men and 19 women, 25 to 69 years old, and their normal‐weight controls, BMI 18.5 to 24.9, matched for gender, age, and height. Body composition was assessed using DXA. Physical activity was measured with Actigraph accelerometers (MTI, Fort Walton Beach, FL) worn by each participant for 7 consecutive days. Results: Accelerometry data indicated that overweight/obese adults recorded ～60 counts per minute less per day and spent 21 minutes less engaged in moderate or greater intensity activity than their normal‐weight counterparts. Although 71% to 94% of those studied met 1995 recommendations, only 13% of overweight/obese subjects and 26% of normal‐weight participants met 2002 exercise recommendations. Discussion: These results suggest that daily minutes spent in moderate‐intensity activity or greater are associated with weight status and that the 2002 IOM recommendations may be difficult to meet even for normal‐weight individuals.     

Biracial Differences in Physical Activity and Body Composition Among Women

Overweight among black females is almost two times as frequent as among white females. Genetics, caloric intake, and physical activity have been identified as possible explanatory factors. This study assessed the differences in physical activity and body composition in 76 white and 66 black adult females. Black women had significantly higher (p=.0001) percent body fat (32.2 ± 7.1) than white women (27.7 ± 6.5) with a similar difference in weight (4.4 kg) approaching significance (p=.055). Physical activity was assessed using a structured 24-hour recall instrument. A purposive sampling design was implemented to control for age, education and occupation. A summary physical activity value unit for the 24-hour period revealed a significantly greater mean value for white females (41.93 + 4.7) than for black females (40.01 ± 3.9) suggesting white females were more physically active (p=.02) although this was not a function of biracial differences in play/recreation and exercise/sport type of activities. Although both black and white females were found to be sedentary (MET value ± 2) over 90 percent of the time, black women were significantly more sedentary (p=.03). Biracial differences in discretionary non-exercise oriented activities may contribute to different rates of overweight observed between black and white women.     

Relationship of Physical Fitness to Prevalence and Incidence of Overweight among Schoolchildren

Objectives: We examined the relationship between comprehensive fitness tests and overweight using a school surveillance system in a racially diverse city in the United States. Research Methods and Procedures: Trained physical education teachers measured weight, height, and fitness annually from 2001 to 2003. We compiled data for a cross‐sectional analysis (11, 845 measurements on 6297 students, 5 to14 years of age) and a 1‐year prospective analysis (4215 measurements on 2927 students not overweight at baseline, 5 to 13 years of age). Overweight was defined as a BMI ≥95th percentile (Centers for Disease Control and Prevention 2000 growth charts), and underfit was defined as failing at least one of five fitness tests: endurance run, abdominal strength, flexibility, upper body strength, and agility (Amateur Athletic Union and Fitnessgram). Associations between fitness and overweight were examined using multivariate logistic regression models, adjusting for sociodemographic status and repeated measurements over time. Results: The mean number of fitness tests passed was lower among students with a BMI above the 80th percentile. Overweight incidence over 1 year was 7% and 2% for underfit and fit girls, respectively (odds ratio, 3.3; 95% confidence interval, 2.0 to 5.6). Not passing either the endurance run or upper body strength test was associated with overweight incidence in both boys and girls. After adjusting for baseline BMI, the endurance run remained a significant predictor of incident overweight among girls (odds ratio, 2.0; 95% confidence interval, 1.1 to 3.5). Discussion: Findings support a cross‐sectional inverse relationship between physical fitness and overweight among school‐aged children. The direction of causation between fitness and overweight is not clearly established and merits further study.     

The Effects of Overfeeding on Spontaneous Physical Activity in Obesity Prone and Obesity Resistant Humans

Despite living in an environment that promotes weight gain in many individuals, some individuals maintain a thin phenotype while self‐reporting expending little or no effort to control their weight. When compared with obesity prone (OP) individuals, we wondered if obesity resistant (OR) individuals would have higher levels of spontaneous physical activity (SPA) or respond to short‐term overfeeding by increasing their level of SPA in a manner that could potentially limit future weight gain. SPA was measured in 55 subjects (23 OP and 32 OR) using a novel physical activity monitoring system (PAMS) that measured body position and movement while subjects were awake for 6 days, either in a controlled eucaloric condition or during 3 days of overfeeding (1.4× basal energy) and for the subsequent 3 days (ad libitum recovery period). Pedometers were also used before and during use of the PAMS to provide an independent measure of SPA. SPA was quantified by the PAMS as fraction of recording time spent lying, sitting, or in an upright posture. Accelerometry, measured while subjects were in an upright posture, was used to categorize time spent in different levels of movement (standing, walking slowly, quickly, etc.). There were no differences in SPA between groups when examined across all study periods (P > 0.05). However, 3 days following overfeeding, OP subjects significantly decreased the amount of time they spent walking (?2.0% of time, P = 0.03), whereas OR subjects maintained their walking (+0.2%, P > 0.05). The principle findings of this study are that increased levels of SPA either during eucaloric feeding or following short term overfeeding likely do not significantly contribute to obesity resistance although a decrease in SPA following overfeeding may contribute to future weight gain in individuals prone to obesity.     

High Plasma Phospholipase A2 Activity,Inflammation Markers,and LDL Alterations in Obesity With or Without Type 2 Diabetes

Plasma phospholipases A₂ (PLA₂) hydrolyze phospholipids of circulating lipoproteins or deposited in arteries producing bioactive lipids believed to contribute to the atherosclerotic inflammatory response. PLA₂(s) are elevated in obesity and type 2 diabetes (T2D) but it is not clear which of these conditions is the cause since they frequently coexist. This study attempts to evaluate if high plasma PLA₂(s) activities and markers of their effects in lipoproteins are associated with obesity or T2D diabetes, or with both. Total PLA₂ and Ca²⁺‐dependent and ‐independent activities, lipids, lipoproteins, apoAI, and apoB apolipoproteins and affinity of apoB‐lipoproteins for arterial proteoglycans were measured, as well as Inflammation markers. These parameters were evaluated in plasma samples of four groups: (i) apparently healthy controls with normal BMI (nBMI), (ii) obese subjects with no T2D, (iii) patients with T2D but with nBMI, and (iv) obese patients with T2D. PLA₂ activities were measured in the presence and absence of Ca²⁺ and in the presence of specific inhibitors. Obese subjects, with or without T2D, had high activities of total PLA₂ and of Ca²⁺‐dependent and Ca²⁺‐independent enzymes. The activities were correlated with inflammation markers in obese subjects with and without diabetes and with alterations of low‐density lipoproteins (LDLs) that increased their affinity for arterial proteoglycans. Ca²⁺‐dependent secretory (sPLA₂) enzymes were the main responsible of the obesity‐associated high activity. We speculate that augmented PLA₂(s) activity that increases affinity of circulating LDL for arterial intima proteoglycans could be another atherogenic component of obesity.