[Show abstract][Hide abstract] ABSTRACT: Objective
To determine if consumption of a reduced-carbohydrate (CHO) diet would result in preferential loss of adipose tissue under eucaloric conditions, and whether changes in adiposity were associated with changes in postprandial insulin concentration.
In a crossover-diet intervention, 30 women with PCOS consumed a reduced-CHO diet (41:19:40%energy from CHO:protein:fat) for 8 weeks and a standard diet (55:18:27) for 8 weeks. Body composition by DXA and fat distribution by CT were assessed at baseline and following each diet phase. Insulin AUC was obtained from a solid meal test (SMT) during each diet phase.
Participants lost 3.7% and 2.2% total fat following the reduced-CHO diet and STD diet, resp. (p< 0.05 for difference between diets). The reduced-CHO diet induced a decrease in subcutaneous-abdominal, intra-abdominal, and thigh-intermuscular adipose tissue (-7.1%, -4.6%, and -11.5%, resp.), and the STD diet induced a decrease in total lean mass. Loss of fat mass following the reduced CHO diet arm was associated with lower insulin AUC (p< 0.05) during the SMT.
In women with PCOS, consumption of a diet lower in CHO resulted in preferential loss of fat mass from metabolically harmful adipose depots, whereas a diet high in CHO appeared to promote repartitioning of lean mass to fat mass.
[Show abstract][Hide abstract] ABSTRACT: To test the hypothesis that a breakfast meal with high carbohydrate/low fat results in an earlier increase in postprandial glucose and insulin, a greater decrease below baseline in postprandial glucose, and an earlier return of appetite, compared to a low carbohydrate/high fat meal.
Overweight but otherwise healthy adults (n=64) were maintained on one of two eucaloric diets: high carbohydrate/low fat (HC/LF; 55:27:18% kcals from carbohydrate: fat: protein) versus low carbohydrate/high fat (LC/HF; 43:39:18% kcals from carbohydrate: fat: protein). After 4 weeks of acclimation to the diets, participants underwent a meal test during which circulating glucose and insulin and self-reported hunger and fullness, were measured before and after consumption of breakfast from their assigned diets.
The LC/HF meal resulted in a later time at the highest and lowest recorded glucose, higher glucose concentrations at 3 and 4 hours post-meal, and lower insulin incremental area under the curve. Participants consuming the LC/HF meal reported lower appetite 3 and 4 hours following the meal, a response that was associated with the timing of the highest and lowest recorded glucose.
Modest increases in meal arbohydrate content at the expense of fat content may facilitate weight gain over the long-term by contributing to an earlier rise and fall of postprandial glucose concentrations and an earlier return of appetite.
[Show abstract][Hide abstract] ABSTRACT: Previous studies suggest that circulating 25(OH)D may favorably influence cardiorespiratory fitness and fat oxidation. However, these relationships have not been examined in older adult women of different ethnic groups. The objectives of this study were to determine whether serum 25(OH)D is related to cardiovascular fitness (VO2max) in sedentary women ages ≥60 years and to determine whether these associations differ between African Americans (AA) and European Americans (EA). A secondary aim was to determine whether serum 25(OH)D is correlated with respiratory quotient (RQ) during submaximal exercise. This cross-sectional analysis included 67 AA and EA women ages 60-74 years. VO2max was measured by a modified Bruce graded treadmill protocol, and measurements were adjusted for percent fat and lean body mass assessed by air displacement plethysmography. Indirect calorimetry was used to measure RQ at rest and during four submaximal exercise tests. Fasting blood samples were obtained to quantify serum 25(OH)D. Serum 25(OH)D was associated with VO2max (ml/kg LBM/min) independent of percent body fat (r = 0.316, p = 0.010). However, subgroup analysis revealed that this relationship was specific to AA (r = 0.727, p = 0.005 for AA; r = 0.064, p = 0.643 for EA). In all subjects combined, 25(OH)D was inversely correlated (p < 0.01) with all measures of submaximal RQ. Higher serum 25(OH)D was associated with greater cardiorespiratory fitness in older adult AA women. Among both AA and EA, inverse associations between serum 25(OH)D and RQ suggest that women with higher levels of circulating vitamin D also demonstrated greater fat oxidation during submaximal exercise.
[Show abstract][Hide abstract] ABSTRACT: We conducted a study designed to evaluate whether the benefits of intentional weight loss exceed the potential risks in a group of community-dwelling obese older adults who were at increased risk for cardiometabolic disease. The CROSSROADS trial used a prospective randomized controlled design to compare the effects of changes in diet composition alone or combined with weight loss with an exercise only control intervention on body composition and adipose tissue deposition (Specific Aim #1: To compare the effects of changes in diet composition alone or combined with weight loss with an exercise only control intervention on body composition, namely visceral adipose tissue), cardiometabolic disease risk (Specific Aim #2: To compare the effects of a change in diet composition alone or combined with weight loss with an exercise only control intervention on cardiometabolic disease risk), and functional status and quality of life (Specific Aim #3: To compare the effects of a change in diet composition alone or combined with weight loss with an exercise only control intervention on functional status and quality of life). Participants were randomly assigned to one of three groups: Exercise Only (Control) Intervention, Exercise + Diet Quality + Weight Maintenance Intervention, or Exercise + Diet Quality + Weight Loss Intervention. CROSSROADS utilized a lifestyle intervention approach consisting of exercise, dietary, and behavioral components. The development and implementation of the CROSSROADS protocol, including a description of the methodology, detailing specific elements of the lifestyle intervention, assurances of treatment fidelity, and participant retention; outcome measures and adverse event monitoring; as well as unique data management features of the trial results, are presented in this article.
Journal of nutrition in gerontology and geriatrics. 01/2014; 33(4):376-400.
[Show abstract][Hide abstract] ABSTRACT: The role of vitamin D in cardiovascular health remains debated as results have been inconsistent. Previous studies have not considered the bioavailability of 25-hydroxy vitamin D [25(OH)D]. Objectives of our study were to investigate the association between serum concentrations of total, free and bioavailable 25(OH)D and independent predictors of cardiovascular risk such as flow mediated dilatation (FMD) and augmentation index (AIx).
This cross-sectional study included 47 post-menarchal, adolescent females [31 African American (AA) and 16 European American (EA)].
AIx was standardized to a heart rate of 75 beats/min (AIx75). Free and bioavailable 25(OH)D concentrations were calculated from standard formulas.
Mean age of the participants was 15.8±1.4 years and mean body mass index was 23.1±4.0 kg/m2. Serum total 25(OH)D was not associated with FMD, but was positively associated with AIx75 in the adjusted model (rho = 0.4, P = 0.03). AIx75 was positively associated with bioavailable 25(OH)D (rho = 0.4, P = 0.004) and free 25(OH)D (rho = 0.4, P = 0.009) and the associations persisted after adjusting for covariates. In race-specific analyses, total, free and bioavailable 25(OH)D were strongly positively associated with AIx75 in AA (rho = 0.5, 0.4, 0.4, respectively), which persisted even after adjusting for covariates. Whereas in EA there was an inverse association between total 25(OH)D and AIx75 in EA (rho = -0.6), which attenuated after adjusting for covariates.
Circulating total, free and bioavailable 25(OH)D were associated with arterial stiffness in adolescent girls, and these associations were race dependent. Notwithstanding, the implications of associations between vascular function indices and 25(OH)D remains unclear.
PLoS ONE 01/2014; 9(12):e114689. · 3.53 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Context: We hypothesized that similar to the coordinated homeostatic regulation of most hormones, the concentration of free and bioavailable 25-hydroxy vitamin D [25(OH)D] will be tightly controlled by total 25(OH)D and vitamin D binding protein (VDBP); and, that the VDBP concentrations will be associated with insulin resistance status. Objective: Our primary objective was to investigate associations between total, free and bioavailable 25(OH)D and VDBP. We also evaluated the relationships of VDBP with insulin resistance indices. Study design was cross sectional in the setting of a University children's hospital. The relative concentration of bioavailable 25(OH)D to total 25(OH)D [bioavailable 25(OH)D /total 25(OH)D was expressed as a percentage [% bioavailable 25(OH)D]. Results: Subjects were 47, post menarchal, female adolescents, mean age 15.8 ± 1.4 years, mean BMI 23.1 ± 4.0 kg/m(2). Total 25(OH)D was strongly associated with VDBP (rho = 0.57, P = <0.0001). At lower total 25(OH)D concentrations, the concentration of bioavailable 25(OH)D relative to total 25(OH)D was higher (23.8% vs. 14.9%, P<0.0001), whereas the relative concentration of free 25(OH)D was similar (P=0.44). VDBP was inversely associated with fasting insulin (rho=-0.51, P=0.0003) and HOMA-IR (rho=-0.45, P=0.002), and positively with WBISI (rho=0.33, P=0.02); these relationships were persisted after adjusting for percent fat and attenuated after adjusting for race. Conclusion: Our data suggest that, VDBP concentrations are regulated by total 25(OH)D levels to maintain adequate concentrations of bioavailable 25(OH)D. VDBP concentrations are inversely associated with hyperinsulinemia and insulin resistance.Background.
The Journal of Clinical Endocrinology and Metabolism 10/2013; · 6.31 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Historically, obesity was thought to be advantageous for maintaining healthy bones due to the greater bone mineral density observed in overweight individuals. However, recent observations of increased fracture in some obese individuals have led to concern that common metabolic complications of obesity, such as type 2 diabetes, metabolic syndrome, impaired glucose tolerance, insulin resistance, hyperglycemia, and inflammation may be associated with poor bone health. In support of this hypothesis, greater visceral fat, a hallmark of insulin resistance and metabolic syndrome, is associated with lower bone mineral density. Research is needed to determine if and how visceral fat and/or poor metabolic health are causally associated with bone health. Clinicians should consider adding a marker metabolic health, such as waist circumference or fasting plasma glucose concentration, to other known risk factors for osteoporosis and fracture.
Journal of Clinical Densitometry 09/2013; · 1.71 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Context:Animal studies indicate that osteocalcin (OC), particularly the undercarboxylated isoform (unOC), affects insulin sensitivity and secretion, but definitive data from humans are lacking.Objective:To determine if total OC and unOC are independently associated with insulin sensitivity and β-cell response in overweight/obese adults; whether glucose tolerance status affects these associations; and whether associations are independent of bone formation, as reflected in procollagen type 1 amino propeptide (P1NP).Design, Setting, and Participants:This was a cross-sectional study conducted at a University Research Center involving 63 overweight/obese adults with normal (n=39) or impaired fasting glucose (IFG, n=24).Main outcome measures:Serum concentrations of total/undercarboxylated OC and P1NP were assessed by RIA; insulin sensitivity was determined by intravenous glucose tolerance test (SI-IVGTT), liquid meal test (SI-meal), and HOMA-IR; β-cell response to glucose (basal, PhiB; dynamic, PhiD; static, PhiS; and total, PhiTOT) was derived using C-peptide modeling of meal test data; and intra-abdominal adipose tissue (IAAT) was measured using CT scanning.Results:Multiple linear regression, adjusting for IAAT and P1NP, revealed that total OC was positively associated with SI-IVGTT (P<0.01) in the total sample. OC was not associated with SI-meal or HOMA-IR. In participants with IFG, unOC was positively associated with PhiS and PhiTOT (P<0.05) independent of insulin sensitivity.Conclusions:In overweight/obese individuals, total OC may be associated with skeletal muscle but not hepatic insulin sensitivity. unOC is uniquely associated with β-cell function only in individuals with IFG. Further research is needed to probe the causal inference of these relationships, and to determine if indirect nutrient sensing pathways underlie these associations.
The Journal of Clinical Endocrinology and Metabolism 04/2013; · 6.31 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: OBJECTIVE: To assess ictal adiponectin (ADP) levels before and after acute abortive treatment in women episodic migraineurs. METHODS: Peripheral blood specimens were collected from women episodic migraineurs before and after acute abortive treatment with sumatriptan/naproxen sodium vs placebo. Univariate and multivariate models were utilized to examine the relationship between serum total ADP (T-ADP), ADP oligomers (high molecular weight [HMW], middle molecular weight, and low molecular weight [LMW]-ADP), and ADP ratio levels and pain severity. Paired t-tests and random intercept longitudinal models were utilized to assess the mean changes in T-ADP, ADP oligomers, and ratios over time in treatment responders and nonresponders. RESULTS: Twenty participants (11 responders, 9 nonresponders) have been studied to date. In all participants, increases in the HMW : LMW ADP ratio were associated with an increase in pain severity. For every 1 point increase in the HMW : LMW ratio, pain severity increased by 0.22 (Confidence Interval [CI]: 0.07, 0.37; P = .004). In contrast, for every 0.25 μg/mL increase in LMW-ADP, pain severity decreased by 0.20 (CI: -0.41, -0.002; P = .047). In treatment responders, T-ADP levels were reduced at 30 minutes (12.52 ± 3.4; P = .03), 60 minutes (12.32 ± 3.2; P = .017), and 120 minutes (12.65 ± 3.2; P = .016) after treatment as compared with onset (13.48 ± 3.8). Additionally, in responders, the HMW : LMW ratio level was greater at pain onset (3.70 ± 1.9 μg/mL) as compared with nonresponders (2.29 ± 0.71 μg/mL), P = .050. Responders also showed a decrease in the HMW : LMW ratio at 60 minutes (2.37 ± 1.1; P = .002) and 120 minutes (2.76 ± 1.4; P = .02) after treatment as compared with onset (3.70 ± 1.9). These changes in responders remained significant after adjusting for covariates, including measured body mass index (m-BMI). Although nonresponders showed no significant changes in unadjusted T-ADP or ADP oligomer or ratio levels, the HMW : LMW ratio was increased in nonresponders after adjustments (P = .025). CONCLUSION: In this pilot study of women episodic migraineurs, the HMW : LMW ADP ratio level was associated with migraine severity and predictive of acute treatment response. ADP and the HMW : LMW ratio of ADP represent potential novel biomarkers and drug targets for episodic migraine.
Headache The Journal of Head and Face Pain 03/2013; 53(3):474-490. · 2.94 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT: The assessment of insulin sensitivity and secretion provides useful information about the metabolic health of an individual. Invasive methods are needed to assess insulin sensitivity and secretion but these are difficult to perform in young children. WHAT THIS STUDY ADDS: The relatively less invasive liquid meal test provided an estimate of insulin sensitivity in a pediatric population that was comparable to that obtained via a more invasive frequently-sampled intravenous glucose tolerance test (FSIGT). Both meal- and FSIGT-derived estimates of insulin sensitivity were inversely associated with children's adiposity. The meal-derived estimate of insulin sensitivity, but not that derived by the FSIGT, was associated with fasting insulin and triglyceride concentrations. Insulin sensitivity and β-cell function are useful indices of metabolic disease risk but are difficult to assess in young children because of the invasive nature of commonly used methodology. A meal-based method for assessing insulin sensitivity and β-cell function may at least partially alleviate concerns. The objectives of this study were to: (i) determine the association of insulin sensitivity assessed by liquid meal test with that determined by an insulin-modified frequently sampled intravenous glucose tolerance test (FSIGT); (ii) examine the association of insulin sensitivity derived from each test with measures of body composition, fat distribution and metabolic health (lipids, fasting insulin and glucose, and surrogate indices of insulin sensitivity); and (iii) examine the associations of indices of β-cell function derived from each test with total and regional adiposity. Forty-seven children (7-12 years) underwent both a liquid meal test and an FSIGT. The insulin sensitivity index derived from the meal test (SI-meal) was positively associated with that from the FSIGT (SI-FSIGT; r = 0.63; P < 0.001), and inversely with all measures of insulin secretion derived from the meal test. Both SI-meal and SI-FSIGT were associated with measures of total and regional adiposity. SI-meal, but not SI-FSIGT, was associated with triglycerides and fasting insulin, after adjusting for ethnicity, gender, pubertal stage and fat mass. Basal insulin secretion measured during the meal test was positively associated with all measures of adiposity, independent of insulin sensitivity. In conclusion, a liquid meal offers a valid and sensitive means of assessing insulin sensitivity and β-cell responsivity in young children.
[Show abstract][Hide abstract] ABSTRACT: What is already known about this subject Children born to women with gestational diabetes have greater risk for obesity. Obesity in adults and children is associated with blunted postprandial gut hormone responses. What this study adds Children of women with gestational diabetes have a blunted postprandial response of GLP-1. Children of women with gestational diabetes have high fasting PYY concentrations. BACKGROUND: Intrauterine exposure to gestational diabetes mellitus (GDM) increases risk for obesity. Obesity is associated with a blunted postprandial gut hormone response, which may impair satiety and thereby contribute to weight gain. The postprandial response of gut hormones among children of women with GDM has not previously been investigated. OBJECTIVE: To examine whether children of women with GDM have suppressed peptide-tyrosine-tyrosine (PYY) and glucagon-like-peptide-1 (GLP-1), and higher concentrations of ghrelin, following a meal challenge. A secondary objective was to investigate associations of these hormones with children's free-living energy intake. METHODS: Children (n = 42) aged 5-10 years were stratified into two groups: offspring of GDM mothers (OGD) and of non-diabetic mothers (CTRL). Body composition was measured by dual-energy X-ray absorptiometry, and circulating PYY, GLP-1 and total ghrelin were measured during a liquid meal challenge. Energy intake was assessed by three 24-h diet recalls. RESULTS: Between-groups analyses of fasting and incremental area under the curve (AUC) found no differences in ghrelin. Incremental AUC for GLP-1 was greater among the CTRL vs. OGD (P < 0.05), and fasting PYY, but not incremental AUC, was higher among OGD vs. CTRL (P < 0.01). Associations of fasting and incremental AUC for each gut hormone with children's usual energy intake did not differ significantly by group. CONCLUSIONS: Further research is needed to more fully examine the potential role of postprandial GLP-1 suppression and high-fasting PYY concentrations on the feeding behaviour and risk for obesity among children exposed to GDM in utero.
[Show abstract][Hide abstract] ABSTRACT: BACKGROUND: Risk for obesity differs with ethnicity/race and is associated with insulin sensitivity (SI), insulin responsiveness, and dietary glycemic load (GL). The objective of this study was to test the hypotheses that, 1) obesity-prone, normal weight, African-American (AA) women would be more insulin sensitive than BMI-matched, never overweight AA women; 2) increased adiposity over time would be associated with greater baseline SI and higher dietary GL in AA but not European-American (EA) women; and 3) increased adiposity over time would be predicted by SI in women with high but not low acute insulin response to glucose (AIRg). METHODS: Two controlled weight loss interventions were conducted involving overweight (BMI 25.0-29.9 kg/m2) premenopausal AA and EA women. The first included matching with normal-weight (BMI <25.0 kg/m2) controls following weight loss, and then comparing SI. The second included a 1-year follow-up of weight-reduced participants to identify predictors of change in %body fat. Main outcome measure in the first study was insulin sensitivity (SI) as assessed with intravenous glucose tolerance test (IVGTT), and in the second study was change in %fat, as assessed with DXA, over one year. AIRg was assessed during IVGTT, and free-living diet was determined by food record. RESULTS: In the first study, formerly overweight AA women were 43% more insulin sensitive than BMI-matched never overweight AA (P < 0.05). In the second study, SI was positively associated with change in %fat over 1 year only in AA women (P < 0.05) and women with high AIRg (P < 0.05). In addition, AA who were insulin sensitive and who consumed a higher GL diet tended to gain greater %fat (P = 0.086 for diet x SI interaction). In both studies, AA women had higher AIRg (P < 0.001) than EA women. CONCLUSIONS: Formerly overweight (obesity-prone) AA women were more insulin sensitive than never overweight AA women, a quality that may predispose to adiposity, particularly when combined with a high GL diet. This ethnicity/race-specific effect may be due to high insulin responsiveness among AA.
[Show abstract][Hide abstract] ABSTRACT: Excess weight gain during both pre- and postnatal life increases risk for obesity in later life. Although a number of gestational and early life contributors to this effect have been identified, there is a dearth of research to examine whether gestational factors and weight gain velocity in infancy exert independent effects on subsequent body composition and fat distribution.
To test the hypothesis that birth weight, as a proxy of prenatal weight gain, and rate of weight gain before 6 months would be associated with total and truncal adiposity at 12 months of age.
Healthy, term infants (N = 47) were enrolled in the study and rate of weight gain (g/day) was assessed at 0-3 months, 3-6 months, and 6-12 months.
Total and regional body composition were measured by dual-energy X-ray absorptiometry (DXA) at 12 months. Stepwise linear regression modeling indicated that lean mass at 12 months, after adjusting for child length, was predicted by rate of weight gain during each discrete period of infancy (P < 0.05), and by maternal pre-pregnancy BMI (P < 0.05). Total fat mass at 12 months was predicted by rate of weight gain during each discrete period (P < 0.01), and by older maternal age at delivery (P < 0.05). Trunk fat mass at 12 months, after adjusting for leg fat mass, was predicted by rate of weight gain from 0-3 months and 3-6 months (P < 0.05).
Results suggest that growth during early infancy may be a critical predictor of subsequent body composition and truncal fat distribution.
[Show abstract][Hide abstract] ABSTRACT: Abstract Background: This study aimed to determine whether oxidative stress was related to cardiovascular risk indices in children, and whether an exercise intervention would reduce oxidative stress. Methods: A randomized trial of two different doses of exercise and a no-exercise control group included 112 overweight and obese children, 7-11 years old. Plasma isoprostane levels were obtained at baseline and after the intervention. Cross-sectional analysis of oxidative stress and metabolic markers at baseline was performed. The effect of the exercise training on oxidative stress was tested. Results: Lower isoprostane levels were observed in blacks. At baseline, isoprostane was positively related to measures of fatness (BMI, waist circumference, percent body fat), insulin resistance and β-cell function (fasting insulin, insulin area under the curve, Matsuda index, disposition index, oral disposition index), and several lipid markers (low-density lipoprotein, triglycerides, total cholesterol), and inversely with fitness [peak oxygen consumption (VO(2))], independent of race, sex, and cohort. No relation was found with visceral fat, blood pressure, or glycemia. Independent of percent body fat, isoprostane predicted triglycerides, β=0.23, total cholesterol-to-high-density lipoprotein (TC/HDL) ratio, β=0.23, and insulin resistance (insulin area under the curve, β=0.24, Matsuda index, β=-0.21, oral disposition index, β=0.33). Exercise did not reduce oxidative stress levels, despite reduced fatness and improved fitness in these children. Conclusions: Isoprostane levels were related to several markers of cardiovascular risk at baseline; however, despite reduced fatness and improved fitness, no effect of exercise was observed on isoprostane levels. To our knowledge, this is the first report in children to demonstrate a correlation of oxidative stress with disposition index, fitness, and TC/HDL ratio, the first to test the effect on oxidative stress of an exercise intervention that reduced body fat, and the first such exercise intervention study to include a substantial proportion of black children.
[Show abstract][Hide abstract] ABSTRACT: The purpose of this study was to examine food preferences of older adults living in the Black Belt Region of the Southeastern United States and the extent to which food preferences vary according to ethnicity, gender, and educational level. 270 older adults who were receiving home health services were interviewed in their home and were queried regarding their favorite foods. Descriptive statistics were used to characterize the sample. Chi-square analysis or one-way analyses of variance was used, where appropriate, in bivariate analyses, and logistic regression models were used in multivariate analyses. A total of 1,857 favorite foods were reported (mean per person = 6.88). The top ten favorite foods reported included: 1) chicken (of any kind), 2) collard greens, 3) cornbread, 4) green or string beans, 5) fish (fried catfish is implied), 6) turnip greens, 7) potatoes, 8) apples, 9) tomatoes, fried chicken, and eggs tied, and 10) steak and ice cream tied. African Americans and those with lower levels of education were more likely to report traditional Southern foods among their favorite foods and had a more limited repertoire of favorite foods. Findings have implications for understanding health disparities that may be associated with diet and development of culturally-appropriate nutrition interventions.
[Show abstract][Hide abstract] ABSTRACT: OBJECTIVE: Qualitative aspects of diet may affect body composition and propensity for weight gain or loss. We tested the hypothesis that consumption of a relatively low glycemic load (GL) diet would reduce total and visceral adipose tissue under both eucaloric and hypocaloric conditions. DESIGN AND METHODS: Participants were 69 healthy overweight men and women. Body composition was assessed by DXA and fat distribution by CT scan at baseline, after 8 weeks of a eucaloric diet intervention, and after 8 weeks of a hypocaloric (1000 kcal/day deficit) diet intervention. Participants were provided all food for both phases, and randomized to either a low GL diet (<45 points per 1000 kcal; n = 40) or high GL diet (>75 points per 1000 kcal, n = 29). RESULTS: After the eucaloric phase, participants who consumed the low GL diet had 11% less intra-abdominal fat (IAAT) than those who consumed the high GL diet (P < 0.05, adjusted for total fat mass and baseline IAAT). Participants lost an average of 5.8 kg during the hypocaloric phase, with no differences in the amount of weight loss with diet assignment (P = 0.39). Following weight loss, participants who consumed the low GL diet had 4.4% less total fat mass than those who consumed the high GL diet (P < 0.05, adjusted for lean mass and baseline fat mass). CONCLUSIONS: Consumption of a relatively low GL diet may affect energy partitioning, both inducing reduction in IAAT independent of weight change, and enhancing loss of fat relative to lean mass during weight loss.
[Show abstract][Hide abstract] ABSTRACT: Heavier individuals have higher bone mineral density (BMD) than individuals of lower body weight, but it is unclear whether BMD changes in proportion to body weight during weight loss. This study compared BMD relative to body weight following a six month weight loss program and a one year weight maintenance phase in premenopausal women and determined whether African American (AA) and European-American (EA) women's BMD respond similarly during weight loss. Premenopausal women (n=115, 34 ± 5 yrs.) were evaluated in an overweight state (BMI between 27-30 kg/m(2) ), following an 800 kcal/day diet/exercise program designed to reduce BMI <25 kg/m(2) , and one year following weight loss. Results indicated that BMD relative to body weight (Z-scores) increased after weight loss, but decreased during the one year weight maintenance phase. All one year follow up BMD Z-scores were increased (except L1) compared to baseline measurements (P < 0.05). These sites included the hip neck (0.088, P=0.014), total hip (0.099, P=0.001), L2 (0.127, P=0.013), L3 (0.135, P=0.014), and L4 (0.199, P=0.002). AAs had significantly higher absolute BMD at all sites (P<0.05) compared to EAs, but no time by race interactions were evident during weight loss (except in L3). These results may indicate that weight loss is safe with regard to bone health for overweight premenopausal women.
[Show abstract][Hide abstract] ABSTRACT: Pediatric studies have shown that aerobic exercise reduces metabolic risk, but dose-response information is not available.
To test the effect of different doses of aerobic training on insulin resistance, fatness, visceral fat, and fitness in overweight, sedentary children and to test moderation by sex and race.
Randomized controlled efficacy trial conducted from 2003 through 2007 in which 222 overweight or obese sedentary children (mean age, 9.4 years; 42% male; 58% black) were recruited from 15 public schools in the Augusta, Georgia, area.
Children were randomly assigned to low-dose (20 min/d; n = 71) or high-dose (40 min/d; n = 73) aerobic training (5 d/wk; mean duration, 13 [SD, 1.6] weeks) or a control condition (usual physical activity; n = 78).
The prespecified primary outcomes were postintervention type 2 diabetes risk assessed by insulin area under the curve (AUC) from an oral glucose tolerance test, aerobic fitness (peak oxygen consumption [VO2]), percent body fat via dual-energy x-ray absorptiometry, and visceral fat via magnetic resonance, analyzed by intention to treat.
The study had 94% retention (n = 209). Most children (85%) were obese. At baseline, mean body mass index was 26 (SD, 4.4). Reductions in insulin AUC were larger in the high-dose group (adjusted mean difference, -3.56 [95% CI, -6.26 to -0.85] × 10(3) μU/mL; P = .01) and the low-dose group (adjusted mean difference, -2.96 [95% CI, -5.69 to -0.22] × 10(3) μU/mL; P = .03) than the control group. Dose-response trends were also observed for body fat (adjusted mean difference, -1.4% [95% CI, -2.2% to -0.7%]; P < .001 and -0.8% [95% CI, -1.6% to -0.07%]; P = .03) and visceral fat (adjusted mean difference, -3.9 cm3 [95% CI, -6.0 to -1.7 cm3]; P < .001 and -2.8 cm3 [95% CI, -4.9 to -0.6 cm3]; P = .01) in the high- and low-dose vs control groups, respectively. Effects in the high- and low-dose groups vs control were similar for fitness (adjusted mean difference in peak VO2, 2.4 [95% CI, 0.4-4.5] mL/kg/min; P = .02 and 2.4 [95% CI, 0.3-4.5] mL/kg/min; P = .03, respectively). High- vs low-dose group effects were similar for these outcomes. There was no moderation by sex or race.
In this trial, after 13 weeks, 20 or 40 min/d of aerobic training improved fitness and demonstrated dose-response benefits for insulin resistance and general and visceral adiposity in sedentary overweight or obese children, regardless of sex or race.
clinicaltrials.gov Identifier: NCT00108901.
JAMA The Journal of the American Medical Association 09/2012; 308(11):1103-12. · 29.98 Impact Factor