Dataset Information

Randomized trial on the effects of a 7-d low-glycemic diet and exercise intervention on insulin resistance in older obese humans.

ABSTRACT:

Background

The optimal combination of diet and exercise that produces the greatest reversal of obesity-related insulin resistance is unknown.

Objectives

We examined the effects of a combined 7-d low-glycemic index (low-GI) diet and exercise training intervention on insulin sensitivity in older obese humans.

Design

Participants [n = 32; mean (+/-SEM) age: 66 +/- 1 y; body mass index (in kg/m(2)): 33.8 +/- 0.7] were randomly assigned to a parallel, double-blind, controlled-feeding trial and underwent supervised aerobic exercise (EX; 60 min/d at 80-85% maximum heart rate) in combination with either a low-GI (LoGI + EX: 41.1 +/- 0.4) or a high-GI (HiGI + EX: 80.9 +/- 0.6) diet. All meals were provided and were isocaloric to individual energy requirements. Insulin sensitivity and hepatic glucose production were assessed with a 40-mU x m(-2) x min(-1) hyperinsulinemic euglycemic clamp combined with a [6,6-(2)H(2)]-glucose infusion.

Results

After the intervention, small decreases were observed in body weight (-1.6 +/- 0.2 kg; P < 0.0001) and fat mass (-1.7 +/- 0.9%; P = 0.004) in both groups. Maximal aerobic capacity ( O(2)max) also improved slightly (0.06 +/- 0.02 L/min; P = 0.004). Resting systolic blood pressure, fasting glucose, insulin, triglycerides, and cholesterol all decreased after the study (all P < 0.05). Larger changes in systolic blood pressure and O(2max) were seen in the LoGI + EX group. Insulin-stimulated glucose disposal (P < 0.001), insulin suppression of hepatic glucose production (P = 0.004), and postabsorptive fat oxidation (P = 0.03) improved equally in both groups after the intervention.

Conclusions

These findings suggest that the metabolic improvements after short-term exercise training in older obese individuals are dependent on increased physical activity and are not influenced by a low-GI diet. However, a low-GI diet has added benefit in alleviating hypertension, thus reducing the risk of diabetic and vascular complications.

SUBMITTER: Solomon TP

PROVIDER: S-EPMC2762157 | biostudies-literature | 2009 Nov

REPOSITORIES: biostudies-literature

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Publications

Randomized trial on the effects of a 7-d low-glycemic diet and exercise intervention on insulin resistance in older obese humans.

Solomon Thomas P J TP Haus Jacob M JM Kelly Karen R KR Cook Marc D MD Riccardi Michelle M Rocco Michael M Kashyap Sangeeta R SR Barkoukis Hope H Kirwan John P JP

The American journal of clinical nutrition 20090930 5

<h4>Background</h4>The optimal combination of diet and exercise that produces the greatest reversal of obesity-related insulin resistance is unknown.<h4>Objectives</h4>We examined the effects of a combined 7-d low-glycemic index (low-GI) diet and exercise training intervention on insulin sensitivity in older obese humans.<h4>Design</h4>Participants [n = 32; mean (+/-SEM) age: 66 +/- 1 y; body mass index (in kg/m(2)): 33.8 +/- 0.7] were randomly assigned to a parallel, double-blind, controlled-fe ...[more]

PMID: 19793849

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Project description:Abstract Objectives Obesity imposes risk to cardiometabolic health; however, intentional weight loss in obese older adults remains controversial. Using data from the CROSSROADS Study (clinicaltrials.gov #NCT00955903), this ancillary study investigated effects of exercise with and without intentional weight loss on changes in cardiometabolic risk assessed by four risk-scoring tools. Methods Participants (n = 134, 39% male, 23% African American, 70.2 ± 4.7 y) were randomized to exercise (n = 48), exercise + nutrient-dense weight maintenance diet (n = 44), or exercise + nutrient-dense caloric restriction of 500 kcals/day (n = 42). The following risk scores were calculated using baseline and 12-month data: Framingham risk assessment, Cardiometabolic Disease Staging (CMDS), metabolic syndrome classification by the International Diabetes Federation (IDF), and metabolic syndrome classification by the National Cholesterol Education Program's Adult Treatment Panel (ATP III). Generalized Estimating Equations were employed to determine differences between groups with ethnicity, sex, and age as covariates. Results Group-time interaction was not significant in application of IDF or ATPIII. Group-time interaction was significant for Framingham and CMDS (P = 0.005 and 0.041, respectively). Upon post-hoc analysis, significant within-group improvements in Framingham scores were observed for exercise + weight maintenance (P < 0.001, r = −1.682) and exercise + weight loss (P = 0.020, r = −0.881). In analysis of between-group differences in Framingham scores, a significant decrease was observed in the exercise + weight maintenance group (P = 0.001, r = −1.723) compared to the exercise group. For CMDS, the exercise + weight loss group had significant within-group improvements (P = 0.023, r = - 0.102). For between-group differences in CMDS, the exercise + weight loss group showed significant risk score reduction (P = 0.012, r = −0.142) compared to the exercise group. Conclusions Risk assessment by Framingham and CMDS showed greater sensitivity to change in cardiometabolic risk factors. Results suggest obese older adults can lower cardiometabolic risk by engaging in exercise + weight maintenance or exercise + weight loss by moderate caloric restriction. Funding Sources R01AG033094 NIA, K07AG043588 NIA, P30DK056336 NIDDK.

Project description:BackgroundLow glycemic index (LGI) diet has shown to be effective in reducing maternal and neonatal complications in high-risk pregnancies.ObjectiveThis trial aimed to examine the effectiveness of individualized LGI diet consultations based on the accurate diet glycemic load (GL) assessment tool on maternal and neonatal insulin resistance levels and diet behavior changes in overweight and obese pregnant women.MethodsOverweight and obese pregnant women were recruited before 16 weeks of gestation and randomized to the LGI diet arm or the control arm. All participants received standard dietary education according to the Chinese Dietary Guide for Pregnant Women. In the intervention arm, additional individualized dietary GL assessments were performed using an app and instructions of lowering diet glycemic index (GI) to achieve LGI diet were provided by a clinical dietitian at early, middle, and late gestation. Primary outcomes were serum insulin at late gestation, incidence of gestational diabetes mellitus (GDM) for mothers, and cord blood C-peptide level of neonates.ResultsIn total, 400 subjects were randomized and received different interventions. There were no significant differences in maternal serum insulin levels (13.2 [9.3-13.2] uU/mL vs 12.4 [10.5-12.4] uU/mL), incidence of GDM (45 [22.5%] vs 43 [21.5%]), or cord blood C-peptide levels (mean 0.9ng/mL [SD 0.7] vs mean 0.8ng/mL [SD 0.6]) in the intervention group compared with the controls. The diet GI at late gestation was similar (mean 63.2 [SD 10.4] vs mean 64.3 [SD 10.4]), whereas greater diet fiber intake was observed in the intervention group (mean 11.6 grams [SD 8.0] vs mean 9.0 grams [SD 5.6]; P=.006). Adherence measurements did not significantly differ between 2 groups.ConclusionsIndividualized LGI diet consultations for overweight and obese pregnant women failed to make a significant difference in maternal or neonatal insulin resistance compared with the standard gestational diet consultation.Trial registrationClinicalTrials.gov NCT01628835; http://clinicaltrials.gov/ct2/show/NCT01628835 (Archived by WebCite at http://www.webcitation.org/77LHgWP0k).

Project description:Abstract Objectives The Visceral Adiposity Index (VAI) was developed to estimate adipose tissue dysfunction as well as visceral fat distribution. In an ancillary analysis of the CROSSROADS Study (clinicaltrials.gov #NCT00955903), this study investigated the effects of exercise with and without intentional energy restriction on VAI changes among older adults with obesity. Methods Participants (n = 163, 37.4% male, 70.3 ± 4.7 years) were randomized to the following groups: exercise only, exercise + nutrient-dense weight maintenance diet, and exercise + nutrient-dense energy restriction of 500 kcal/d. Visceral adiposity determined by magnetic resonance imaging (MRI) and dual-energy X-ray absorptiometry (DXA), anthropometrics, and cardiometabolic biomarkers were assessed at baseline and 12 months. Waist circumference, body mass index, triglycerides, and high-density lipoprotein (HDL) cholesterol were used to compute VAI at both time points. Data were analyzed utilizing Spearman's correlations and general linear models to determine differences among groups following adjustment for covariates. Results Among all participants, significant correlations were observed between VAI and glucose, insulin, tumor necrosis factor-alpha (TNF-α), and the adiponectin: leptin ratio at baseline (r = 0.343, P < 0.001; r = 0.363, P < 0.001; r = 0.200, P = 0.011; r = −0.246, P = 0.002, respectively). DXA and MRI measures of visceral adiposity were not significantly correlated with VAI. Upon completion of the 12-month study period, there were significant differences in VAI among groups [F (2,137) = 5.957, P = 0.003)]. Post hoc analysis revealed that VAI was significantly lower in the exercise + nutrient-dense energy restriction group compared to the exercise only group (P = 0.002). Conclusions Results suggest that VAI may be an adequate measure of adipose tissue dysfunction, yet its ability to estimate levels of visceral adiposity warrants further investigation to determine clinical utility. Nonetheless, results suggest that an exercise + nutrient-dense energy restriction intervention may reduce VAI among older adults with obesity. Funding Sources NIH.

Project description:BACKGROUND:Obesity causes frailty in older adults; however, weight loss might accelerate age-related loss of muscle and bone mass and resultant sarcopenia and osteopenia. METHODS:In this clinical trial involving 160 obese older adults, we evaluated the effectiveness of several exercise modes in reversing frailty and preventing reduction in muscle and bone mass induced by weight loss. Participants were randomly assigned to a weight-management program plus one of three exercise programs - aerobic training, resistance training, or combined aerobic and resistance training - or to a control group (no weight-management or exercise program). The primary outcome was the change in Physical Performance Test score from baseline to 6 months (scores range from 0 to 36 points; higher scores indicate better performance). Secondary outcomes included changes in other frailty measures, body composition, bone mineral density, and physical functions. RESULTS:A total of 141 participants completed the study. The Physical Performance Test score increased more in the combination group than in the aerobic and resistance groups (27.9 to 33.4 points [21% increase] vs. 29.3 to 33.2 points [14% increase] and 28.8 to 32.7 points [14% increase], respectively; P=0.01 and P=0.02 after Bonferroni correction); the scores increased more in all exercise groups than in the control group (P<0.001 for between-group comparisons). Peak oxygen consumption (milliliters per kilogram of body weight per minute) increased more in the combination and aerobic groups (17.2 to 20.3 [17% increase] and 17.6 to 20.9 [18% increase], respectively) than in the resistance group (17.0 to 18.3 [8% increase]) (P<0.001 for both comparisons). Strength increased more in the combination and resistance groups (272 to 320 kg [18% increase] and 288 to 337 kg [19% increase], respectively) than in the aerobic group (265 to 270 kg [4% increase]) (P<0.001 for both comparisons). Body weight decreased by 9% in all exercise groups but did not change significantly in the control group. Lean mass decreased less in the combination and resistance groups than in the aerobic group (56.5 to 54.8 kg [3% decrease] and 58.1 to 57.1 kg [2% decrease], respectively, vs. 55.0 to 52.3 kg [5% decrease]), as did bone mineral density at the total hip (grams per square centimeter; 1.010 to 0.996 [1% decrease] and 1.047 to 1.041 [0.5% decrease], respectively, vs. 1.018 to 0.991 [3% decrease]) (P<0.05 for all comparisons). Exercise-related adverse events included musculoskeletal injuries. CONCLUSIONS:Of the methods tested, weight loss plus combined aerobic and resistance exercise was the most effective in improving functional status of obese older adults. (Funded by the National Institutes of Health; LITOE ClinicalTrials.gov number, NCT01065636 .).

Dataset Information

Randomized trial on the effects of a 7-d low-glycemic diet and exercise intervention on insulin resistance in older obese humans.

Background

Objectives

Design

Results

Conclusions

Publications

Randomized trial on the effects of a 7-d low-glycemic diet and exercise intervention on insulin resistance in older obese humans.

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