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Geoff D C Ball

Publications and source records attributed to Geoff D C Ball.

17 recordsLinked to original sources
PubMed2026

Understanding and Usefulness of Effect Size and Certainty of Evidence: A Cross-Sectional Survey of Evidence-Based Practice Competencies Among US Registered Dietitians.

INTRODUCTION: Understanding of absolute and relative effect estimates, and determining effect size and certainty of evidence corresponding to effect estimates, represent fundamental evidence-based practice competencies that promote informed clinical decision-making. While research has been conducted in the medical profession, based on our literature review there is no published research on these competencies in the nutrition and dietetics profession. METHODS: Among registered dietitians, our main objectives were to assess (1) their understanding and perceived usefulness of three absolute and two relative effect estimate approaches to determine effect size, (2) their perceived usefulness of certainty of evidence, and (3) factors influencing their understanding and perceived usefulness. We conducted a web-based, cross-sectional survey by recruiting dietitians from the Academy of Nutrition and Dietetics (United States). Participants received effect estimates based on hypothetical dietary interventions vs. usual diet for reducing myocardial infarction risk. RESULTS: Of the 11,050 dietitians who received the survey link, 210 participated, and only completers (n = 114) were included in our analysis. Participants demonstrated a similar understanding of the relative (27.6%) and absolute (27.5%) effect estimates, with Risk Difference being the best understood approach and Number Needed to Treat being the least (30.7% vs. 24.6% correct responses). While perceived usefulness scores were similar between five approaches, they were highest when data was presented as Relative Risk [mean (SD): 4.82 (1.50)]. Dietitians rated the usefulness of certainty of evidence favorably [mean (SD): 5.07 (1.83), on a 7-point scale], and no factors were associated with correct understanding. CONCLUSION: Dietitians may have limited understanding of effect size thresholds presented in our survey, a finding mostly consistent with surveys of other health professionals. To optimize informed decision-making between dietitians and clients, dietetic programs and continuing education platforms should consider additional training on effect estimate approaches (relative and absolute), and determining effect sizes and certainty of evidence for effect estimates.

Clinical nutrition↗
PubMed2006

Prevalence estimates of overweight and obesity in Cree preschool children in northern Quebec according to international and US reference criteria.

OBJECTIVES: We estimated the prevalence of overweight and obesity in Cree Canadian children aged 5 years (n=1044) using international and US growth references and examined the longitudinal tracking of weight categories between ages 2 and 5 years (n=562). METHODS: Weight categories based on body mass index (calculated from measured heights and weights) were derived from the International Obesity Task Force (IOTF) and the Centers for Disease Control and Prevention (CDC) references. RESULTS: According to the IOTF reference, 52.9% of children were overweight (31.6%) or obese (21.3%) whereas with the CDC reference, 64.9% were overweight (27.5%) or obese (37.4%). The IOTF and CDC references provided dissimilar tracking of weight categories. Based on the IOTF reference, 4.9% of the children who were normal weight at age 2 years were obese at age 5 years. Based on the CDC reference, 14.9% of children categorized as normal weight at age 2 years were obese at age 5 years. CONCLUSIONS: The IOTF reference provided more conservative estimates of obesity than the CDC reference, and longitudinal analyses showed dissimilar tracking of weight categories with the 2 references. Public health responses to obesity prevalence estimates should be made with awareness of methodological limitations.

Body Mass Index↗
PubMed2006

Longitudinal changes in insulin sensitivity, insulin secretion, and beta-cell function during puberty.

OBJECTIVE: To determine longitudinal changes in insulin sensitivity (SI), insulin secretion, and beta-cell function during puberty in white and black youth. STUDY DESIGN: The tolbutamide-modified frequently sampled intravenous glucose tolerance test and minimal modeling were used to measure SI, the acute insulin response to glucose (AIRg), and beta-cell function (disposition index, DI) in white (n = 46) and black (n = 46) children (mean [+/-SD] age at baseline = 10.2 +/- 1.7 years). Growth curve models (including 272 observations) with SI, AIRg, and DI regressed on Tanner stage were run after adjusting for covariates. RESULTS: After adjusting for covariates, growth curve models revealed that SI decreased and subsequently recovered by the end of puberty in whites and blacks (both p < .05), AIRg decreased linearly across Tanner stages in both races (both p < .001), and DI decreased across puberty in blacks (p = .001) but not in whites (p = .2). CONCLUSIONS: White and black youth exhibited transient insulin resistance and diminished AIRg during puberty. The progressive decline in DI among blacks versus whites may reflect a unique effect of puberty on beta-cell compensation in blacks. Future studies are needed to identify whether this difference contributes to the increased risk of type II diabetes in young blacks.

Black or African American↗
PubMed2006

Effects of resistance training on insulin sensitivity in overweight Latino adolescent males.

PURPOSE: Insulin resistance is thought to be a core defect in the pathophysiology of obesity-related comorbidities in children, such as type 2 diabetes. Exercise training is known to improve insulin resistance and reduce the risk of type 2 diabetes in adults. However, very little is known regarding the effects of exercise on insulin resistance in youth. Therefore, we examined the effects of a 16-wk resistance training exercise intervention on insulin sensitivity in youth at high risk for developing type 2 diabetes. METHODS: Twenty-two overweight Latino adolescent males were randomly assigned to either a twice-per-week resistance training group (RT=11) or a nonexercising control group (C=11) for 16 wk. Strength was assessed by one-repetition maximum, body composition was quantified by dual-energy x-ray absorptiometry, and insulin sensitivity was determined by the frequently sampled intravenous glucose tolerance test with minimal modeling. RESULTS: Significant increases in upper- and lower-body strength were observed in the RT compared with the C group. The RT group significantly increased insulin sensitivity compared with the C group (P<0.05), and this increase remained significant after adjustment for changes in total fat mass and total lean tissue mass (P<0.05). Compared with baseline values, insulin sensitivity increased 45.1+/-7.3% in the RT group versus -0.9+/-12.9% in controls (P<0.01). CONCLUSION: A twice-per-week 16-wk resistance training program can significantly increase insulin sensitivity in overweight Latino adolescent males independent of changes in body composition.

Adolescent↗
PubMed2006

Aerobic fitness among Caucasian, African-American, and Latino youth.

OBJECTIVE: The prevalence of obesity and related comorbidities has dramatically increased in the pediatric population in recent years, and youth from ethnic minorities appear to be disproportionately affected. Although several factors play a role in these ethnic health disparities, evidence suggests fitness may also be an important mediator of disease risk in children. Therefore, the purpose of the present investigation was to compare aerobic fitness (VO2peak) in healthy Caucasian (C), African-American (AA), and Latino (L) youth and to evaluate differences after controlling for gender, maturational stage, and body composition. MEASURES: Seventy-three healthy boys and girls [C (n=18), AA (n=19), and L (n=36)] aged 7-14 years participated in the study. VO2peak was evaluated using an all-out, progressive treadmill protocol, total body composition was estimated via dual-energy x-ray absorptiometry, and ethnicity was determined via parental questionnaire. RESULTS: VO2peak relative to total body mass (mL/kg/min) was significantly lower in Latinos compared to either Caucasian or African-American children. Further, after controlling for gender, maturational stage, and body composition, L (1.68 +/- 0.05 L/min) and AA (1.57 +/- 0.05 L/min) youth had significantly lower VO2peak compared to C (1.84 +/- 0.04 L/ min; P<.05) children. CONCLUSION: These results suggest that Latino and African-American children have lower aerobic fitness levels than Caucasian children and this effect is independent of gender, maturation, and body composition.

Adolescent↗
PubMed2005

Dietary fat intake and insulin resistance in black and white children.

OBJECTIVE: The purpose of this study was to determine whether dietary fat intake above current Acceptable Macronutrient Distribution Range (AMDR) guidelines was associated with greater insulin resistance in black and white children. RESEARCH METHODS AND PROCEDURES: We studied 142 healthy children (n = 81 whites, n = 61 blacks), 6.5 to 14 years old. Dietary composition was determined by repeated 24-hour dietary recall, body composition by DXA, visceral fat by computed tomography, and insulin sensitivity (SI) and acute insulin response to glucose (AIRg) by frequently sampled intravenous glucose tolerance test. Subjects were categorized by ethnicity (white/black) and dietary fat intake (above-AMDR/within-AMDR guidelines), and differences were analyzed by 2 x 2 analysis of covariance, adjusting for covariates. RESULTS: After adjusting for total body fat, gender, and Tanner stage, subjects consuming dietary fat above AMDR intake guidelines had lower SI and higher AIRg. This effect was specific to black children (32% lower SI and 62% higher AIRg in above-AMDR compared with within-AMDR blacks) and was not seen in whites. DISCUSSION: In black, but not white, children, those with dietary fat intake above current AMDR guidelines had lower SI and higher AIRg than those who met AMDR guidelines. These findings support current AMDR guidelines for dietary fat in black children and adolescents. The mechanism(s) underlying the ethnic differences in the relationship between dietary fat intake and SI in children require further investigation.

Adolescent↗
PubMed2005

The relation of sugar intake to beta cell function in overweight Latino children.

BACKGROUND: Few studies have investigated the association between sugar intake and insulin dynamics in children, and none have examined this association in overweight Latino youth. OBJECTIVE: We aimed to examine the relation between dietary components, especially sugar intake, and insulin dynamics in overweight Latino youth. DESIGN: We examined 63 overweight Latino children aged 9-13 y. Dietary intake was determined by 3-d records, and body composition was measured with dual-energy X-ray absorptiometry. Insulin sensitivity (S(I)), acute insulin response (AIR), and disposition index (an index of beta cell function) were measured by using a frequently sampled intravenous-glucose-tolerance test and minimal modeling. Hierarchical regression analysis ascertained the potential independent relation between insulin dynamics and dietary components. RESULTS: The relation between macronutrient intake and any variable related to insulin dynamics was not significant. However, higher total sugar intake, although not related to S(I), was significantly associated with lower AIR (beta = -0.296, P = 0.045) and lower beta cell function (beta = -0.421, P = 0.043), independent of the covariates age, sex, body composition, Tanner stage, and energy intake. Sugar-sweetened beverage intakes trended toward inverse association with lower AIR (beta = -0.219, P = 0.072) and beta cell function (beta = -0.298, P = 0.077). CONCLUSIONS: In overweight Latino children, higher intakes of sugar and sugar-sweetened beverages were associated with lower AIR and disposition index, which suggested that these children already have early signs of poor beta cell function. These results emphasize the need for early nutritional interventions to reduce daily sugar intake in overweight Latino children and potentially reduce their risk for type 2 diabetes.

Absorptiometry, Photon↗
PubMed2005

Decreased beta-cell function in overweight Latino children with impaired fasting glucose.

OBJECTIVE: To determine whether overweight Latino children with impaired fasting glucose (IFG) (> or = 100 mg/dl) have increased insulin resistance or decreased beta-cell function compared with those with normal fasting glucose (NFG). RESEARCH DESIGN AND METHODS: We studied 207 healthy overweight Latino children, aged 8-13 years, with a family history of type 2 diabetes. Fasting and 2-h glucose and insulin were assessed by oral glucose tolerance test. Insulin sensitivity (S(i)), the acute insulin response to glucose (AIRg), and the disposition index (DI; an index of beta-cell function) were determined using the insulin-modified intravenous glucose tolerance test and minimal modeling. Body composition was determined by dual-energy X-ray absorptiometry. RESULTS: There were no differences in body composition between NFG (n = 182) and IFG (n = 25) children. Compared with children with NFG, children with IFG had higher fasting and 2-h glucose values and higher fasting insulin. After adjusting for covariates, children with IFG had no difference in S(i) but 15% lower DI than NFG children (2,224 +/- 210 vs. 2,613 +/- 76, P < 0.05). Multivariate linear regression showed that AIRg and DI, but not S(i), were significant predictors of fasting blood glucose. CONCLUSIONS: In overweight Latino adolescents with a family history of type 2 diabetes, IFG is associated with impaired beta-cell function and therefore may identify children likely to be at risk for progression to type 2 diabetes. The actual risk of progression of IFG to type 2 diabetes remains to be determined by prospective longitudinal studies.

Adolescent↗
PubMed2005

Physical activity, aerobic fitness, self-perception, and dietary intake in at risk of overweight and normal weight children.

Differences in physical activity, aerobic fitness, self-perception, and dietary intake were examined in a sample of six- to ten-year-olds at risk of overweight, and in normal weight boys and girls. Participants (n=20 at risk of overweight [BMI > or =85th percentile]; n=115 normal weight [BMI <85th percentile]; n=68 boys; n=67 girls) had anthropometric, physical activity, aerobic fitness, self-perception, and dietary intake measurements at zero, three, six, and 12 months. Over the 12-month period, normal weight children were more physically active (F=4.1, p<0.05) and aerobically fit (F=14.3, p<0.001), and possessed higher self-perceptions of social acceptance (F=7.3, p<0.01) than their at risk of overweight peers. Fitness differences between the sexes were not apparent at baseline, but emerged over the long term (F=7.9, p<0.01). Overall, boys consumed more total energy, fat, carbohydrate, and protein than did girls, while the entire sample consumed diets low in vegetables and fruits and meat and alternatives, and high in "other" foods. These observations highlight key disparities in lifestyle-related behaviours and perceptions between groups of children according to overweight status and sex. The findings underscore the importance of longitudinal studies in youth because cross-sectional studies may reflect transient differences.

Anthropometry↗
PubMed2005

Cardiovascular fitness and the metabolic syndrome in overweight latino youths.

PURPOSE: To determine whether cardiovascular fitness (.)VO(2max) is associated with the metabolic syndrome and its individual features in overweight Latino youths. METHODS: A total of 163 overweight Latino boys and girls (body mass index (BMI) percentile = 97.0 +/- 3.1; age = 11.2 +/- 1.7 yr) with a family history of Type 2 diabetes participated in this investigation. The metabolic syndrome was defined as having three or more of the following risk factors: abdominal obesity, high blood pressure, low HDL-cholesterol, high triglycerides, and impaired glucose tolerance. (.)VO(2max) was determined by a progressive treadmill test to exhaustion, and body composition was assessed using dual energy x-ray absorptiometry. RESULTS: (.)VO(2max) was not correlated with any individual risk factor of the metabolic syndrome after adjusting for gender, age, and body composition in partial analysis. Furthermore, ANCOVA revealed that children with zero, one, two, or three or more risk factors did not differ in regards to fitness levels. CONCLUSION: (.)VO(2max) is not independently associated with the metabolic syndrome or any individual feature in overweight youths of Latino ethnicity after controlling for differences in confounding variables.

Adolescent↗
PubMed2004

Rating of figures used for body image assessment varies depending on the method of figure presentation.

OBJECTIVE: To determine the effect of method of figure presentation on figure rating scales used for body image assessment. METHODS: Ratings of current, ideal, and socially acceptable body sizes were elicited from 360 university students. Male and female figure drawings ranging from thin to obese were presented to subjects using one of three presentation methods. Figures were presented as an ordered array, an unordered array, or they were placed individually on cards that were fixed in order from thin to obese. RESULTS: Figure ratings were significantly different among methods for the selection of current and ideal figure and socially acceptable body sizes. DISCUSSION: The method of figure presentation had an influence on figure ratings. These findings suggest that the manner in which figures are presented to research participants for the evaluation of body image constructs may be responsible, in part, for the discordant results reported in the body image assessment literature. Future research is required to address potential reasons why the method of figure presentation results in different figure ratings.

Adult↗
PubMed2004

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 O(2) 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 O(2) 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 O(2) per minute), was not independently related to insulin sensitivity or secretion, suggesting that VO(2max) influences insulin dynamics indirectly through fat mass.

Adolescent↗
PubMed2004

Impaired glucose tolerance and reduced beta-cell function in overweight Latino children with a positive family history for type 2 diabetes.

The objective of this study was to examine relationships between impaired glucose tolerance (IGT) and body composition and insulin-related phenotypes in 150 overweight Latino children with a family history of type 2 diabetes. Glucose tolerance was assessed by an oral glucose challenge. Body composition was assessed by dual energy x-ray absorptiometry and magnetic resonance imaging. Insulin sensitivity, the acute insulin response, and the disposition index (DI), as an index of beta-cell function, were determined by an iv glucose tolerance test and compared between normal glucose-tolerant and IGT children. IGT was present in 28% of children, and was similar across obesity groups, but higher in children exposed to gestational diabetes mellitus (41% IGT). There were no significant differences in body composition, fat distribution, insulin sensitivity, or acute insulin response, but DI was significantly lower in IGT children by 16% (P < 0.02), and DI was inversely related to age. In conclusion, IGT is present in 28% of overweight Latino children with a family history of type 2 diabetes, is not influenced by obesity, is more prevalent in children exposed to gestational diabetes mellitus, and is related to poor beta-cell function, which shows signs of deterioration with age in this population.

Absorptiometry, Photon↗
PubMed2004

Relation between acanthosis nigricans and insulin sensitivity in overweight Hispanic children at risk for type 2 diabetes.

OBJECTIVE: To investigate in a population of Hispanic children if 1) the presence of acanthosis nigricans (AN) is related to insulin sensitivity (S(i)) independent of adiposity and 2) scale scoring AN severity adds to the clinical estimation of insulin sensitivity, above and beyond the presence or absence AN alone. RESEARCH DESIGN AND METHODS: The study population, 131 Hispanic overweight children (mean BMI percentile 97.0 +/- 3.1, 72 boys, 59 girls, ages 8-13 years, mean Tanner stage 2.4 +/- 1.5) with a family history of type 2 diabetes, underwent a physical examination of the neck to determine AN absence or presence (0-1), AN extent score (0-4 scale), AN texture score (0-3 scale), and an AN combined score (extent + texture; 0-7 scale). S(i) was measured by the frequently sampled intravenous glucose tolerance test and minimal modeling. Multivariate linear regression analysis was used to determine the role of BMI and AN in predicting S(i). RESULTS: BMI was the main predictor of S(i), explaining approximately 41% of the variance. The presence of AN explained an additional 4% of the variability in S(i); scale scoring of AN extent or texture did not significantly improve the prediction. CONCLUSIONS: Although AN is an independent risk factor for insulin resistance in overweight Hispanic children at risk for type 2 diabetes, body adiposity is the primary determinant of insulin sensitivity. In addition, scale scoring AN seems of minimal usefulness in clinically estimating the severity of insulin resistance over and above assessing the presence or absence of AN and calculating BMI.

Acanthosis Nigricans↗
PubMed2003

Childhood obesity in Canada: a review of prevalence estimates and risk factors for cardiovascular diseases and type 2 diabetes.

Childhood obesity in Canada has become increasingly prevalent over the past 2 decades. Despite inconsistencies regarding different anthropometric indicators, cut-offs, and reference populations, both regional and national investigations have revealed high numbers of overweight and obese children and adolescents. A number of risk factors and health consequences have been associated with increased levels of body fatness in youth. Specifically, risk factors for cardiovascular diseases (CVD) and type 2 diabetes are known to develop early in life and tend to emerge in clusters among overweight youngsters. Unhealthy lifestyle behaviours (i.e., physical inactivity), a genetic disposition, and a centralized body fat distribution, all contribute to increased risk. In order to prevent future generations of children from experiencing increased morbidity and mortality as overweight and obese adults, coordinated efforts at all levels (family, school, community, and government) must be established with a long-term commitment to promote healthy nutrition and physical activity behaviours in our youth.

Age Factors↗
PubMed2003

Obesity and risk of type 2 diabetes and cardiovascular disease in children and adolescents.

Overweight/obesity continues to increase in children and adolescents, and annual obesity-related hospital costs in 6-17 yr olds have reached 127 million dollars per year. Overweight children and adolescents are now being diagnosed with impaired glucose tolerance and type 2 diabetes, and they show early signs of the insulin resistance syndrome and cardiovascular risk. Several risk factors have been identified as contributors to the development of type 2 diabetes and cardiovascular risk in youth. These factors include increased body fat and abdominal fat, insulin resistance, ethnicity (with greater risk in African-American, Hispanic, and Native American children), and onset of puberty. There is no clear explanation of how these factors increase risk, but they appear to act in an additive fashion. We hypothesize that the constellation of these risk factors may be especially problematic during the critical period of adolescent development, especially in individuals who may have compromised beta-cell function and an inability to compensate for severe insulin resistance. Therefore, the purpose of this paper is to review the pathophysiology of type 2 diabetes and cardiovascular risk in obese children and adolescents.

Abdomen↗