Effects of a reduced-glycemic-load diet on body weight, body composition, and cardiovascular disease risk markers in overweight and obese adults

Low glycaemic index or low glycaemic load diets for people with overweight or obesity

BACKGROUND

The prevalence of obesity is increasing worldwide, yet nutritional management remains contentious. It has been suggested that low glycaemic index (GI) or low glycaemic load (GL) diets may stimulate greater weight loss than higher GI/GL diets or other weight reduction diets. The previous version of this review, published in 2007, found mainly short-term intervention studies. Since then, randomised controlled trials (RCTs) with longer-term follow-up have become available, warranting an update of this review.

OBJECTIVES

To assess the effects of low glycaemic index or low glycaemic load diets on weight loss in people with overweight or obesity.

SEARCH METHODS

We searched CENTRAL, MEDLINE, one other database, and two clinical trials registers from their inception to 25 May 2022. We did not apply any language restrictions.

SELECTION CRITERIA

We included RCTs with a minimum duration of eight weeks comparing low GI/GL diets to higher GI/GL diets or any other diets in people with overweight or obesity.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. We conducted two main comparisons: low GI/GL diets versus higher GI/GL diets and low GI/GL diets versus any other diet. Our main outcomes included change in body weight and body mass index, adverse events, health-related quality of life, and mortality. We used GRADE to assess the certainty of the evidence for each outcome.

MAIN RESULTS

In this updated review, we included 10 studies (1210 participants); nine were newly-identified studies. We included only one study from the previous version of this review, following a revision of inclusion criteria. We listed five studies as 'awaiting classification' and one study as 'ongoing'. Of the 10 included studies, seven compared low GI/GL diets (233 participants) with higher GI/GL diets (222 participants) and three studies compared low GI/GL diets (379 participants) with any other diet (376 participants). One study included children (50 participants); one study included adults aged over 65 years (24 participants); the remaining studies included adults (1136 participants). The duration of the interventions varied from eight weeks to 18 months. All trials had an unclear or high risk of bias across several domains.  Low GI/GL diets versus higher GI/GL diets Low GI/GL diets probably result in little to no difference in change in body weight compared to higher GI/GL diets (mean difference (MD) -0.82 kg, 95% confidence interval (CI) -1.92 to 0.28; I2 = 52%; 7 studies, 403 participants; moderate-certainty evidence). Evidence from four studies reporting change in body mass index (BMI) indicated low GI/GL diets may result in little to no difference in change in BMI compared to higher GI/GL diets (MD -0.45 kg/m2, 95% CI -1.02 to 0.12; I2 = 22%; 186 participants; low-certainty evidence)at the end of the study periods. One study assessing participants' mood indicated that low GI/GL diets may improve mood compared to higher GI/GL diets, but the evidence is very uncertain (MD -3.5, 95% CI -9.33 to 2.33; 42 participants; very low-certainty evidence). Two studies assessing adverse events did not report any adverse events; we judged this outcome to have very low-certainty evidence. No studies reported on all-cause mortality.    For the secondary outcomes, low GI/GL diets may result in little to no difference in fat mass compared to higher GI/GL diets (MD -0.86 kg, 95% CI -1.52 to -0.20; I2 = 6%; 6 studies, 295 participants; low certainty-evidence). Similarly, low GI/GL diets may result in little to no difference in fasting blood glucose level compared to higher GI/GL diets (MD 0.12 mmol/L, 95% CI 0.03 to 0.21; I2 = 0%; 6 studies, 344 participants; low-certainty evidence).  Low GI/GL diets versus any other diet Low GI/GL diets probably result in little to no difference in change in body weight compared to other diets (MD -1.24 kg, 95% CI -2.82 to 0.34; I2 = 70%; 3 studies, 723 participants; moderate-certainty evidence). The evidence suggests that low GI/GL diets probably result in little to no difference in change in BMI compared to other diets (MD -0.30 kg in favour of low GI/GL diets, 95% CI -0.59 to -0.01; I2 = 0%; 2 studies, 650 participants; moderate-certainty evidence). Two adverse events were reported in one study: one was not related to the intervention, and the other, an eating disorder, may have been related to the intervention. Another study reported 11 adverse events, including hypoglycaemia following an oral glucose tolerance test. The same study reported seven serious adverse events, including kidney stones and diverticulitis. We judged this outcome to have low-certainty evidence. No studies reported on health-related quality of life or all-cause mortality. For the secondary outcomes, none of the studies reported on fat mass. Low GI/GL diets probably do not reduce fasting blood glucose level compared to other diets (MD 0.03 mmol/L, 95% CI -0.05 to 0.12; I2 = 0%; 3 studies, 732 participants; moderate-certainty evidence).  AUTHORS' CONCLUSIONS: The current evidence indicates there may be little to no difference for all main outcomes between low GI/GL diets versus higher GI/GL diets or any other diet. There is insufficient information to draw firm conclusions about the effect of low GI/GL diets on people with overweight or obesity. Most studies had a small sample size, with only a few participants in each comparison group. We rated the certainty of the evidence as moderate to very low. More well-designed and adequately-powered studies are needed. They should follow a standardised intervention protocol, adopt objective outcome measurement since blinding may be difficult to achieve, and make efforts to minimise loss to follow-up. Furthermore, studies in people from a wide range of ethnicities and with a wide range of dietary habits, as well as studies in low- and middle-income countries, are needed.

Encapsulated starch characteristics and its shell matrix mechanisms controlling starch digestion

Encapsulated starch can be classified as physically inaccessible starch or type 1 resistant starch (RS1), which is produced by encapsulating starch granules within food matrices using various encapsulation techniques. Encapsulated starch has the potential to be used as a functional ingredient in low-/medium-glycemic index (GI) foods as it can help control glycemic and insulin responses. Despite its remarkable benefits, the relevant information related to entrapped starch and its application is still insufficient and needs further elucidation. The objective of this work is to present a comprehensive overview of the current techniques utilized for the preparation of encapsulated starch and its characteristics, thereby extending the fundamental knowledge. Furthermore, this review delves into the mechanisms governing starch hydrolysis regulated by shell matrices and provides the prospective utilization of encapsulated starch in food production.

Low-Glycemic Index Diets as an Intervention in Metabolic Diseases: A Systematic Review and Meta-Analysis

We aimed to investigate the effects of a low-glycemic index (GI) diet on the body mass and blood glucose of patients with four common metabolic diseases by conducting a systematic review and meta-analysis of studies comparing a low-GI diet (LGID) and other types of diet. Search terms relating to population, intervention, comparator, outcomes, and study design were used to search three databases: PubMed, Embase, and the Cochrane Library. We identified 24 studies involving 2002 participants. Random-effects models were used for 16 studies in the meta-analysis and stratified analyses were performed according to the duration of the intervention. The systematic review showed that LGIDs slightly reduced body mass and body mass index (BMI) (p < 0.05). BMI improved more substantially after interventions of >24 weeks and there was no inter-study heterogeneity (I² = 0%, p = 0.48; mean difference (MD) = -2.02, 95% confidence interval (CI): -3.05, -0.98). Overall, an LGID had superior effects to a control diet on fasting blood glucose (FBG) and glycosylated hemoglobin. When the intervention exceeded 30 days, an LGID reduced FBG more substantially (MD = -0.34, 95% CI: -0.55, -0.12). Thus, for patients with metabolic diseases, an LGID is more effective at controlling body mass and blood glucose than a high-GI or other diet.

Associations between Dietary Glycemic Index and Glycemic Load Values and Cardiometabolic Risk Factors in Adults: Findings from the China Health and Nutrition Survey

Studies investigating the associations between dietary glycemic index (GI) and glycemic load (GL) values and cardiometabolic risk factors (CMRF) among Chinese populations are strikingly limited. To assess the associations between dietary GI and GL values and CMRF, including dyslipidemia, hyperglycemia, and hyperuricemia in Chinese adults, we extracted data of 7886 apparently healthy adults from the 2009 wave of the China Health and Nutrition Survey. Dietary GI and GL values were calculated using data collected from three consecutive 24 h dietary recalls. Fasting lipid, glucose, and uric acid concentrations were measured and CMRF were defined on the basis of established criteria. There were no significant associations between dietary GI values and CMRF, and analyzing the data by age, sex, body mass index (BMI), and region did not alter these results. Dietary GL values were positively associated with prevalence of hyperuricemia in all participants (Q4 compared with Q1: odds ratio (OR) = 1.46; 95% CI: 1.14, 1.87; p-trend = 0.0030) and prevalence of hypercholesterolemia in participants ≥ 60 years old (Q5 compared with Q1: OR = 1.72; 95% CI: 1.11, 2.68; p-trend < 0.0010). Higher dietary GL but not GI values were associated with increased prevalence of hyperuricemia in apparently healthy Chinese adults and hypercholesterolemia in older Chinese adults. Further studies are required to confirm the public health implication of these findings.

Associations between preconception macronutrient intake and birth weight across strata of maternal BMI

INTRODUCTION

Maternal nutrition during pregnancy is linked with birth outcomes including fetal growth, birth weight, congenital anomalies and long-term health through intra-uterine programming. However, a woman's nutritional status before pregnancy is a strong determinant in early embryo-placental development, and subsequently outcomes for both mother and child. Therefore, the aim of this study was to investigate the association between dietary macronutrient intake in the preconception period with birth weight.

METHODS

We studied a group of 1698 women from the Dutch Perined-Lifelines linked birth cohort with reliable detailed information on preconception dietary macronutrient intake (using a semi quantitative food frequency questionnaire) and data available on birth weight of the offspring. Birth weight was converted into gestational age adjusted z-scores, and macronutrient intake was adjusted for total energy intake using the nutrient residual method. Preconception BMI was converted into cohort-based quintiles. Multivariable linear regression was performed, adjusted for other macronutrients and covariates.

RESULTS

Mean maternal age was 29.5 years (SD 3.9), preconception BMI: 24.7 kg/m2 (SD 4.2) and median daily energy intake was 1812 kcal (IQR 1544-2140). Mean birth weight was 3578 grams (SD 472). When adjusted for covariates, a significant association (adjusted z score [95% CI], P) between polysaccharides and birth weight was shown (0.08 [0.01-0.15], 0.03). When linear regression analyses were performed within cohort-based quintiles of maternal BMI, positive significant associations between total protein, animal protein, fat, total carbohydrates, mono-disaccharides and polysaccharides with birth weight were shown in the lowest quintile of BMI independent of energy intake, intake of other macronutrients and covariates.

CONCLUSION

Out of all macronutrients studied, polysaccharides showed the strongest association with birth weight, independent of energy intake and other covariates. Our study might suggest that specifically in women with low preconception BMI a larger amount of macronutrient intake was associated with increased birth weight. We recommend that any dietary assessment and advise during preconception should be customized to preconception weight status of the women.

The association of glycemic index and glycemic load with elevated blood pressure in Iranian women

Introduction: Dietary intake is a risk factor related to elevated blood pressure (EBP). Few studies have investigated an association of dietary glycemic index (GI) and glycemic load (GL) with the EBP. The aim of the current study was to examine the association of dietary GI and GL with the EBP among a group of healthy women. Methods: This population-based cross-sectional study was conducted on 306 healthy women. Dietary GI and GL were measured using a validated semi-quantitative food frequency questionnaire (FFQ). Blood pressure (BP) was measured twice by a mercury sphygmomanometer from the right arm. Anthropometric measurements were also assessed according to the standard protocols. Results: Before controlling for potential confounders, no significant association was seen between dietary GI/GL and SBP/DBP. Also after controlling for potential confounders, the associations did not change between dietary GI and SBP (odds ratio [OR]: 0.96; 95% CI: 0.42-2.17, P = 0.87), between GI and DBP (OR: 0.72; 95% CI: 0.35-1.45, P = 0.37), as well as between GL and SBP (OR: 1.04; 95% CI: 0.43-2.49, P = 1.00) and between GL and DBP (OR: 1.20; 95% CI: 0.56-2.00, P = 0.61). In a stratified analysis by obesity and overweight, differences between tertiles of GI were not significant (OR: 0.75; 95% CI: 0.42-1.31, P = 0.31), even after adjustment for the potential confounders (OR: 1.54; 95% CI: 0.70-3.40, P = 0.26). Conclusion: This study did not show a significant association between dietary GI/GL and the risk of high SBP/DBP. In addition, no significant association was found between dietary GI/GL and odds of overweight or obesity in adult women.

Low glycaemic index diets as an intervention for obesity: a systematic review and meta-analysis

OBJECTIVES

Low glycaemic index (GI) diets may aid in weight loss by reducing postprandial blood glucose excursions, leading to more stable blood glucose concentrations and therefore a reduction in hunger. To test this hypothesis, we conducted a systematic review and meta-analysis of randomized controlled trials comparing low GI diets with other diet types.

METHODS

We included 101 studies involving 109 study arms and 8,527 participants. We meta-analysed the studies using a random-effects model and conducted subgroup analyses and meta-regression based on control diet, blood glucose control, baseline BMI and dietary GI.

RESULTS

Low GI diets resulted in small but significant improvements in body weight, BMI, LDL and total cholesterol overall, although no individual control diet was significantly different from low GI diets. Studies in people with normal blood glucose who achieved a difference in GI of 20 points or more resulted in a larger reduction in body weight (SMD = -0.26; 95% CIs [-0.43, -0.09]), and total cholesterol (SMD = -0.24; 95% CIs [-0.42, -0.05]) than studies that only achieved a smaller reduction in GI.

CONCLUSIONS

Low GI diets, especially diets achieving a substantial decrease in GI, were moderately effective in lowering body weight. However, efforts should be made to increase compliance with low GI diets, in order for them to be effective in people with overweight and obesity.

Dietary patterns and physical activity in the metabolically (un)healthy obese: the Dutch Lifelines cohort study

BACKGROUND

Diversity in the reported prevalence of metabolically healthy obesity (MHO), suggests that modifiable factors may be at play. We evaluated differences in dietary patterns and physical activity between MHO and metabolically unhealthy obesity (MUO).

METHODS

Cross-sectional data of 9270 obese individuals (30-69 years) of the Lifelines Cohort Study was used. MHO was defined as obesity and no metabolic syndrome risk factors and no cardiovascular disease history. MUO was defined as obesity and ≥2 metabolic syndrome risk factors. Sex-specific associations of dietary patterns (identified by principal component analysis) and physical activity with MHO were assessed by multivariable logistic regression (reference group: MUO). Analyses were adjusted for multiple covariates.

RESULTS

Among 3442 men and 5828 women, 10.2% and 24.4% had MHO and 56.9% and 35.3% MUO, respectively. We generated four obesity-specific dietary patterns. Two were related to MHO, and in women only. In the highest quartile (Q) of 'bread, potatoes and sweet snacks' pattern, odds ratio (OR) (95% CI) for MHO was 0.52 (0.39-0.70). For the healthier pattern 'fruit, vegetables and fish', an OR of 1.36 (1.09-1.71) in Q3 and 1.55 (1.21-1.97) in Q4 was found for MHO. For physical activity, there was a positive association between moderate physical activity and vigorous physical activity in the highest tertile and MHO in women and men, respectively (OR 1.19 (1.01-1.41) and OR 2.02 (1.50-2.71)).

CONCLUSION

The healthier diet -characterized by 'fruit, vegetables and fish'- and moderate physical activity in women, and vigorous physical activity in men may be related to MHO. The (refined) carbohydrate-rich 'bread, potatoes and sweet snacks' dietary pattern was found to counteract MHO in women.

The Effect of Dietary Glycemic Properties on Markers of Inflammation, Insulin Resistance, and Body Composition in Postmenopausal American Women: An Ancillary Study from a Multicenter Protein Supplementation Trial

Controversy exists as to whether high glycemic index/glycemic load (GI/GL) diets increase the risk of chronic inflammation, which has been postulated as a pathogenic intermediary between such diets and age-related alterations in body composition and insulin resistance. We conducted an ancillary study to a randomized, double-blind trial comparing the effects of a whey protein supplement (PRO, n = 38) and a maltodextrin supplement (CHO, n = 46) on bone density to evaluate the impact of a calibrated increase in GI/GL on inflammation, insulin resistance, and body composition in a healthy aging population. Markers of inflammation, HOMA, body composition, and GI/GL (estimated from 3-day food records) were assessed at baseline and 18 months. By 18 months, the GL in the CHO group increased by 34%, 88.4 ± 5.2 → 118.5 ± 4.9 and did not change in the PRO group, 86.5 ± 4.1 → 82.0 ± 3.6 (p < 0.0001). Despite this change there were no differences in serum CRP, IL-6, or HOMA at 18 months between the two groups, nor were there significant associations between GL and inflammatory markers. However, trunk lean mass (p = 0.0375) and total lean mass (p = 0.038) were higher in the PRO group compared to the CHO group at 18 months There were also significant associations for GL and change in total fat mass (r = 0.3, p = 0.01), change in BMI (r = 0.3, p = 0.005), and change in the lean-to-fat mass ratio (r = −0.3, p = 0.002). Our data suggest that as dietary GL increases within the moderate range, there is no detectable change in markers of inflammation or insulin resistance, despite which there is a negative effect on body composition.

Glycemic index, glycemic load, and blood pressure: a systematic review and meta-analysis of randomized controlled trials

Background: High blood pressure is a strong risk factor for cardiovascular disease.Objective: The aim of this study was to determine the associations of dietary glycemic index (GI) and glycemic load (GL) with systolic blood pressure (SBP) and diastolic blood pressure (DBP) in healthy individuals.Design: A systematic review and meta-analysis of randomized controlled trials (RCTs) was carried out. Databases were searched for eligible RCTs in 2 phases. MEDLINE, Embase, CAB Abstracts, BIOSIS, ISI Web of Science, and the Cochrane Library were searched from January 1990 to December 2009. An updated search was undertaken with the use of MEDLINE and Embase from January 2010 to September 2016. Trials were included if they reported author-defined high- and low-GI or -GL diets and blood pressure, were of ≥6 wk duration, and comprised healthy participants without chronic conditions. Data were extracted and analyzed with the use of Stata statistical software. Pooled estimates and 95% CIs were calculated with the use of weighted mean differences and random-effects models.Results: Data were extracted from 14 trials comprising 1097 participants. Thirteen trials provided information on differences in GI between control and intervention arms. A median reduction in GI of 10 units reduced the overall pooled estimates for SBP and DBP by 1.1 mm Hg (95% CI: -0.3, 2.5 mm Hg; P = 0.11) and 1.3 mm Hg (95% CI: 0.2 mm Hg, 2.3; P = 0.02), respectively. Nine trials reported information on differences in GL between arms. A median reduction in GL of 28 units reduced the overall pooled estimates for SBP and DBP by 2.0 mm Hg (95% CI: 0.2, 3.8 mm Hg; P = 0.03) and 1.4 mm Hg (95% CI: 0.1, 2.6 mm Hg; P = 0.03), respectively.Conclusions: This review of healthy individuals indicated that a lower glycemic diet may lead to important reductions in blood pressure. However, many of the trials included in the analysis reported important sources of bias. This trial was registered at PROSPERO as CRD42016049026.

Glycemic load and coronary heart disease in a Mediterranean population: the EPIC Greek cohort study

BACKGROUND AND AIMS

High glycemic load (GL) has been associated with increased coronary heart disease (CHD) risk. We evaluated whether preference of low-GL foods conveys incremental benefits with respect to CHD, especially to people adhering to the traditional Mediterranean diet (MD).

METHODS AND RESULTS

We analyzed data from the Greek European Prospective Investigation into Cancer and Nutrition, including 20,275 participants free of cardiovascular diseases, cancer, or diabetes at baseline and without incident diabetes. Subjects completed a validated, semi-quantitative food frequency questionnaire at enrollment. We calculated a 10-point MD adherence score and the dietary GL, and estimated hazard ratios (HRs) for CHD incidence and mortality through Cox proportional hazard regression. After a median follow-up of 10.4 years, 417 participants developed CHD, and 162 died from the disease. A significant positive association of GL with CHD incidence emerged (HR for the highest versus the lowest tertile = 1.41, 95% confidence interval, CI: 1.05-1.90). HRs for CHD mortality exceeded unity but were not statistically significant. The association with GL was stronger among subjects with higher body mass index. High adherence to MD with low/moderate GL was associated with lower risk of CHD incidence (HR = 0.61, CI: 0.39-0.95) and mortality (HR = 0.47, 95% CI: 0.23-96).

CONCLUSION

High dietary GL increases the risk of CHD. Compared to a high GL diet with suboptimal adherence to the traditional Mediterranean pattern, a low/moderate GL diet that also conforms to the traditional MD principles could lead to a 40% reduced risk for CHD, and over 50% reduced risk for death from CHD.

A randomized, controlled, crossover trial to assess the acute appetitive and metabolic effects of sausage and egg-based convenience breakfast meals in overweight premenopausal women

Background

Dietary protein at breakfast has been shown to enhance satiety and reduce subsequent energy intake more so than carbohydrate or fat. However, relatively few studies have assessed substitution of protein for carbohydrate on indicators of appetite and glucose homeostasis simultaneously.

Methods

The acute appetitive and metabolic effects of commercially-prepared sausage and egg-based breakfast meals at two different protein levels (30 g and 39 g/serving), vs. a low-protein pancake breakfast (3 g protein) and no breakfast (water), were examined in premenopausal women (N = 35; age 32.5 ± 1.6 yr; BMI 24.8 ± 0.5 kg/m²). Test products provided ~280 kcal/serving and similar fat (12–14 g) and fiber contents (0–1 g). Visual Analog Scale ratings for appetite (hunger, fullness, prospective consumption, desire to eat) and repeated blood sampling for plasma glucose and insulin concentrations were assessed throughout each test day. Energy intake was recorded at an ad libitum lunch meal at 240 min.

Results

Results showed increased satiety ratings for both the 30 and 39 g protein meals vs. the low-protein and no breakfast conditions (p < 0.001 for all). Postprandial glucose and insulin excursions were lower following the 30 g and 39 g protein conditions vs. the low-protein condition, with smaller responses following the 39 g vs. 30 g protein condition (p < 0.05 for all). Energy intake at lunch was significantly less (p < 0.001) following the 39 g protein meal (692 kcal) vs. the low-protein and no breakfast conditions (789 and 810 kcal, respectively). Total energy intake from the test condition + lunch was higher (p < 0.01) for the 30 and 39 g meals (982 and 983 kcal, respectively) vs. no breakfast (810 kcal), and less than the low protein breakfast (1064 kcal; p < 0.01 vs. 39 g condition only).

Conclusions

Results suggest that convenience meals providing 30 or 39 g protein/serving produce greater appetite control, lower postprandial glycemia and insulinemia, and reduced subsequent intake at lunch relative to a low-protein control, or no breakfast.

Trial registration

NCT01713114

Dietary substitutions for refined carbohydrate that show promise for reducing risk of type 2 diabetes in men and women

Both genetics and lifestyle contribute to type 2 diabetes (T2D), a condition of elevated circulating glucose induced by a collection of metabolic defects including peripheral insulin resistance, elevated hepatic glucose output, and impaired pancreatic insulin secretion. Because the prevalence of T2D and its modifiable risk factors (overweight/obesity, dyslipidemia, hypertension, and physical inactivity) have been increasing in recent decades, there has been growing interest in lifestyle interventions that target T2D management and prevention. Although it is increasingly recognized that lifestyle interventions aimed at encouraging physical activity and reducing body weight can improve insulin sensitivity, nutritional contributions to T2D risk reduction are less clear. Evidence from prospective cohort and randomized controlled trials suggests that diets rich in refined dietary carbohydrate [particularly those with a high glycemic index (GI)] may elevate T2D risk; however, the appropriate combination of macronutrients to optimize metabolic health has not been fully described. To date, the collective evidence suggests that diets rich in low-GI carbohydrates, cereal fiber, resistant starch, fat from vegetable sources (unsaturated fat), and lean sources of protein should be emphasized, whereas refined sugars and grains (high-GI carbohydrates) are to be avoided in order to lower risk of T2D and its related risk factors and comorbidities.

Mediterranean diet and glycaemic load in relation to incidence of type 2 diabetes: results from the Greek cohort of the population-based European Prospective Investigation into Cancer and Nutrition (EPIC)

AIMS/HYPOTHESIS

The role of diet in the prevention of diabetes remains uncertain. The aim of this study was to investigate two different dietary aspects, i.e. adherence to the Mediterranean diet and glycaemic load (GL), in relation to diabetes occurrence.

METHODS

We analysed data from the Greek cohort of the population-based European Prospective Investigation into Cancer and Nutrition (EPIC). From a total of 22,295 participants, actively followed for a median of 11.34 years, 2,330 cases of incident type 2 diabetes were recorded. All participants completed a validated, interviewer-administered semi-quantitative food frequency questionnaire at enrolment. From this information, we calculated a ten point Mediterranean diet score (MDS), reflecting adherence to the traditional Mediterranean diet, as well as the dietary GL. We estimated HRs and the corresponding 95% CIs of diabetes using Cox proportional hazards regression models adjusted for potential confounders.

RESULTS

A higher MDS was inversely associated with diabetes risk (HR 0.88 [95% CI 0.78, 0.99] for MDS ≥ 6 vs MDS ≤ 3). GL was positively associated with diabetes (HR 1.21 [95% CI 1.05, 1.40] for the highest vs the lowest GL quartile). A significant protection of about 20% was found for a diet with a high MDS and a low GL.

CONCLUSIONS/INTERPRETATION

A low GL diet that also adequately adheres to the principles of the traditional Mediterranean diet may reduce the incidence of type 2 diabetes.

Long-term effects of low glycemic index/load vs. high glycemic index/load diets on parameters of obesity and obesity-associated risks: a systematic review and meta-analysis

AIM

The aim of the present meta-analysis was to investigate the long-term effects of glycemic index-related diets in the management of obesity with a special emphasis on the potential benefits of low glycemic index/load (GI/GL) in the prevention of obesity-associated risks.

DATA SYNTHESIS

Electronic searches for randomized controlled trials (RCTs) comparing low glycemic index/load versus high glycemic index/load diets were performed in MEDLINE, EMBASE and the Cochrane Library. Outcome of interest markers included anthropometric data as well as biomarkers of CVD and glycemic control. Study specific weighted mean differences were pooled using a random effect model. 14 studies were included in the primary meta-analysis. Weighted mean differences in change of C-reactive protein [WMD: -0.43 mg/dl, (95% CI -0.78 to -0.09), p = 0.01], and fasting insulin [WMD: -5.16 pmol/L, (95% CI -8.45 to -1.88), p = 0.002] were significantly more pronounced in benefit of low GI/GL diets. However decrease in fat free mass [WMD: -1.04 kg (95% CI -1.73 to -0.35), p = 0.003] was significantly more pronounced following low GI/GL diets as well. No significant changes were observed for blood lipids, anthropometric measures, HbA1c and fasting glucose. Sensitivity analysis was performed for RCTs excluding subjects with type 2 diabetes. Decreases in C-reactive protein and fasting insulin remained statistically significant in the low GI/GL subgroups.

CONCLUSIONS

The present systematic review provides evidence for beneficial effects of long-term interventions administering a low glycemic index/load diet with respect to fasting insulin and pro-inflammatory markers such as C-reactive protein which might prove to be helpful in the primary prevention of obesity-associated diseases.

Dietary strategies to increase satiety

Obesity has a multifactorial etiology. Although obesity is widespread and associated with serious health hazards, its effective prevention and treatment have been challenging. Among the currently available treatment approaches, lifestyle modification to induce a negative energy balance holds a particularly larger appeal due to its wider reach and relative safety. However, long-term compliance with dietary modifications to reduce energy intake is not effective for the majority. The role of many individual nutrients, foods, and food groups in inducing satiety has been extensively studied. Based on this evidence, we have developed sample weight-loss meal plans that include multiple satiating foods, which may collectively augment the satiating properties of a meal. Compared to a typical American diet, these meal plans are considerably lower in energy density and probably more satiating. A diet that exploits the satiating properties of multiple foods may help increase long-term dietary compliance and consequentially enhance weight loss.

Dietary glycemic index, glycemic load, and risk of coronary heart disease, stroke, and stroke mortality: a systematic review with meta-analysis

BACKGROUND

The relationship between dietary glycemic index, glycemic load and risk of coronary heart disease (CHD), stroke, and stroke-related mortality is inconsistent.

METHODS

We systematically searched the MEDLINE, EMBASE, and Science Citation Index Expanded databases using glycemic index, glycemic load, and cardiovascular disease and reference lists of retrieved articles up to April 30, 2012. We included prospective studies with glycemic index and glycemic load as the exposure and incidence of fatal and nonfatal CHD, stroke, and stroke-related mortality as the outcome variable. Pooled relative risks (RR) and 95% confidence intervals (CI) were calculated using random-effects models.

RESULTS

Fifteen prospective studies with a total of 438,073 participants and 9,424 CHD cases, 2,123 stroke cases, and 342 deaths from stroke were included in the meta-analysis. Gender significantly modified the effects of glycemic index and glycemic load on CHD risk, and high glycemic load level was associated with higher risk of CHD in women (RR=1.49, 95%CI 1.27-1.73), but not in men (RR=1.08, 95%CI 0.91-1.27). Stratified meta-analysis by body mass index indicated that among overweight and obese subjects, dietary glycemic load level were associated with increased risk of CHD (RR=1.49, 95%CI 1.27-1.76; P for interaction=0.003). Higher dietary glycemic load, but not glycemic index, was positively associated with stroke (RR=1.19, 95% CI 1.00-1.43). There is a linear dose-response relationship between dietary glycemic load and increased risk of CHD, with pooled RR of 1.05 (95%CI 1.02-1.08) per 50-unit increment in glycemic load level.

CONCLUSION

High dietary glycemic load is associated with a higher risk of CHD and stroke, and there is a linear dose-response relationship between glycemic load and CHD risk. Dietary glycemic index is slightly associated with risk of CHD, but not with stroke and stroke-related death. Further studies are needed to verify the effects of gender and body weight on cardiovascular diseases.

Impact of postprandial glycaemia on health and prevention of disease

Postprandial glucose, together with related hyperinsulinemia and lipidaemia, has been implicated in the development of chronic metabolic diseases like obesity, type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD). In this review, available evidence is discussed on postprandial glucose in relation to body weight control, the development of oxidative stress, T2DM, and CVD and in maintaining optimal exercise and cognitive performance. There is mechanistic evidence linking postprandial glycaemia or glycaemic variability to the development of these conditions or in the impairment in cognitive and exercise performance. Nevertheless, postprandial glycaemia is interrelated with many other (risk) factors as well as to fasting glucose. In many studies, meal-related glycaemic response is not sufficiently characterized, or the methodology with respect to the description of food or meal composition, or the duration of the measurement of postprandial glycaemia is limited. It is evident that more randomized controlled dietary intervention trials using effective low vs. high glucose response diets are necessary in order to draw more definite conclusions on the role of postprandial glycaemia in relation to health and disease. Also of importance is the evaluation of the potential role of the time course of postprandial glycaemia.

Body composition, dietary composition, and components of metabolic syndrome in overweight and obese adults after a 12-week trial on dietary treatments focused on portion control, energy density, or glycemic index

BACKGROUND

Given the rise in obesity and associated chronic diseases, it is critical to determine optimal weight management approaches that will also improve dietary composition and chronic disease risk factors. Few studies have examined all these weight, diet, and disease risk variables in subjects participating in recommended multi-disciplinary weight loss programs using different dietary strategies.

METHODS

This study compared effects of three dietary approaches to weight loss on body composition, dietary composition and risk factors for metabolic syndrome (MetS). In a 12-week trial, sedentary but otherwise healthy overweight and obese adults (19 M & 138 F; 38.7±6.7 y; BMI 31.8±2.2) who were attending weekly group sessions for weight loss followed either portion control, low energy density, or low glycemic index diet plans. At baseline and 12 weeks, measures included anthropometrics, body composition, 3-day food diaries, blood pressure, total lipid profile, HOMA, C-reactive protein, and fasting blood glucose and insulin. Data were analyzed by repeated measures analysis of variance.

RESULTS

All groups significantly reduced body weight and showed significant improvements in body composition (p<0.001), and components of metabolic syndrome (p<0.027 to 0.002), although HDL decreased (p<0.001). Dietary energy, %fat and %saturated fat decreased while protein intake increased significantly (p<0.001). There were no significant differences among the three groups in any variable related to body composition, dietary composition, or MetS components.

CONCLUSION

Different dietary approaches based on portion control, low energy density, or low glycemic index produced similar, significant short-term improvements in body composition, diet compositin, and MetS components in overweight and obese adults undergoing weekly weight loss meetings. This may allow for flexibility in options for dietary counseling based on patient preference.

Dietary fiber, carbohydrate quality and quantity, and mortality risk of individuals with diabetes mellitus

BACKGROUND

Dietary fiber, carbohydrate quality and quantity are associated with mortality risk in the general population. Whether this is also the case among diabetes patients is unknown.

OBJECTIVE

To assess the associations of dietary fiber, glycemic load, glycemic index, carbohydrate, sugar, and starch intake with mortality risk in individuals with diabetes.

METHODS

This study was a prospective cohort study among 6,192 individuals with confirmed diabetes mellitus (mean age of 57.4 years, and median diabetes duration of 4.4 years at baseline) from the European Prospective Investigation into Cancer and Nutrition (EPIC). Dietary intake was assessed at baseline (1992-2000) with validated dietary questionnaires. Cox proportional hazards analysis was performed to estimate hazard ratios (HRs) for all-cause and cardiovascular mortality, while adjusting for CVD-related, diabetes-related, and nutritional factors.

RESULTS

During a median follow-up of 9.2 y, 791 deaths were recorded, 306 due to CVD. Dietary fiber was inversely associated with all-cause mortality risk (adjusted HR per SD increase, 0.83 [95% CI, 0.75-0.91]) and CVD mortality risk (0.76[0.64-0.89]). No significant associations were observed for glycemic load, glycemic index, carbohydrate, sugar, or starch. Glycemic load (1.42[1.07-1.88]), carbohydrate (1.67[1.18-2.37]) and sugar intake (1.53[1.12-2.09]) were associated with an increased total mortality risk among normal weight individuals (BMI≤25 kg/m(2); 22% of study population) but not among overweight individuals (P interaction≤0.04). These associations became stronger after exclusion of energy misreporters.

CONCLUSIONS

High fiber intake was associated with a decreased mortality risk. High glycemic load, carbohydrate and sugar intake were associated with an increased mortality risk in normal weight individuals with diabetes.

Role of carbohydrate modification in weight management among obese children: a randomized clinical trial

OBJECTIVE

To compare the effectiveness and safety of carbohydrate (CHO)-modified diets with a standard portion-controlled (PC) diet in obese children.

STUDY DESIGN

Obese children (n=102) aged 7-12 years were randomly assigned to a 3-month intervention of a low-CHO (LC), reduced glycemic load (RGL), or standard PC diet, along with weekly dietary counseling and biweekly group exercise. Anthropometry, dietary adherence, and clinical measures were evaluated at baseline and 3, 6, and 12 months. Analyses applied intention-to-treat longitudinal mixed models.

RESULTS

Eighty-five children (83%) completed the 12-month assessment. Daily caloric intake decreased from baseline to all time points for all diet groups (P<.0001), although LC diet adherence was persistently lower (P<.0002). At 3 months, body mass index z score was lower in all diet groups (LC, -0.27 ± 0.04; RGL, -0.20 ± 0.04; PC, -0.21 ± 0.04; P<.0001) and was maintained at 6 months, with similar results for waist circumference and percent body fat. At 12 months, participants in all diet groups had lower body mass index z scores than at baseline (LC, -0.21 ± 0.04; RGL, -0.28 ± 0.04; PC, -0.31 ± 0.04; P<.0001), and lower percent body fat, but no reductions in waist circumference were maintained. All diets demonstrated some improved clinical measures.

CONCLUSION

Diets with modified CHO intake were as effective as a PC diet for weight management in obese children. However, the lower adherence to the LC diet suggests that this regimen is more difficult for children to follow, particularly in the long term.

Tailoring dietary approaches for weight loss

Although the ‘Low-Fat' diet was the predominant public health recommendation for weight loss and weight control for the past several decades, the obesity epidemic continued to grow during this time period. An alternative ‘low-carbohydrate' (Low-Carb) approach, although originally dismissed and even vilified, was comparatively tested in a series of studies over the past decade, and has been found in general to be as effective, if not more, as the Low-Fat approach for weight loss and for several related metabolic health measures. From a glass half full perspective, this suggests that there is more than one choice for a dietary approach to lose weight, and that Low-Fat and Low-Carb diets may be equally effective. From a glass half empty perspective, the average amount of weight lost on either of these two dietary approaches under the conditions studied, particularly when followed beyond 1 year, has been modest at best and negligible at worst, suggesting that the two approaches may be equally ineffective. One could resign themselves at this point to focusing on calories and energy intake restriction, regardless of macronutrient distributions. However, before throwing out the half-glass of water, it is worthwhile to consider that focusing on average results may mask important subgroup successes and failures. In all weight-loss studies, without exception, the range of individual differences in weight change within any particular diet groups is orders of magnitude greater than the average group differences between diet groups. Several studies have now reported that adults with greater insulin resistance are more successful with weight loss on a lower-carbohydrate diet compared with a lower-fat diet, whereas adults with greater insulin sensitivity are equally or more successful with weight loss on a lower-fat diet compared with a lower-carbohydrate diet. Other preliminary findings suggest that there may be some promise with matching individuals with certain genotypes to one type of diet over another for increasing weight-loss success. Future research to address the macronutrient intake component of the obesity epidemic should build on these recent insights and be directed toward effectively classifying individuals who can be differentially matched to alternate types of weight-loss diets that maximize weight-loss and weight-control success.

Treatment Heterogeneity and Individual Qualitative Interaction

Plausibility of high variability in treatment effects across individuals has been recognized as an important consideration in clinical studies. Surprisingly, little attention has been given to evaluating this variability in design of clinical trials or analyses of resulting data. High variation in a treatment's efficacy or safety across individuals (referred to herein as treatment heterogeneity) may have important consequences because the optimal treatment choice for an individual may be different from that suggested by a study of average effects. We call this an individual qualitative interaction (IQI), borrowing terminology from earlier work - referring to a qualitative interaction (QI) being present when the optimal treatment varies across a"groups" of individuals. At least three techniques have been proposed to investigate treatment heterogeneity: techniques to detect a QI, use of measures such as the density overlap of two outcome variables under different treatments, and use of cross-over designs to observe "individual effects." We elucidate underlying connections among them, their limitations and some assumptions that may be required. We do so under a potential outcomes framework that can add insights to results from usual data analyses and to study design features that improve the capability to more directly assess treatment heterogeneity.

Glycemic index and glycemic load are associated with some cardiovascular risk factors among the PREMIER study participants

BACKGROUND

The clinical significance of glycemic index (GI) and glycemic load (GL) is inconclusive.

OBJECTIVE

This study was conducted to examine the association of GI and GL with clinical cardiovascular disease (CVD) risk factors including body weight, blood pressure (BP), serum lipids, fasting glucose, insulin and homocysteine over time among the PREMIER participants.

DESIGN

PREMIER was an 18-month randomized lifestyle intervention trial, conducted from 2000 to 2002, designed to help participants reduce BP by following the Dietary Approaches to Stop Hypertension (DASH) dietary pattern, losing weight, reducing sodium and increasing physical activity. GI and GL were estimated from 24 h diet recall data at baseline, 6 and 18 months after intervention. PROC MIXED model was used to examine the association of changes in GI or GL with changes in CVD risk factors.

RESULTS

A total of 756 randomized participants, 62% females and 34% African Americans and who averaged 50.0±0.3 years old and 95.3±0.7 kg, were included in this report. Neither GI nor GL changes was associated with changes in any risk factors at 6 months. At 18 months, however, the GI change was significantly and positively associated with total cholesterol (TC) change only (p<0.05, β=23.80±12.11 mg/dL or 0.62±0.31 mmol/L) with a significant age interaction. The GL change was significantly associated with TC (p=0.02, β=0.28±0.15 mg/dL or 0.01±0.00 mmol/L) positively and with low density lipoprotein cholesterol (LDL-C) changes negatively (p=0.03, β=-0.01±0.00 mg/dL or -0.00±0.00 mmol/L), and significant age interactions were observed for both.

CONCLUSIONS

GI and GL was associated with TC and LDL-C after controlling for energy, fat and fiber intake and other potential confounders and the associations were modified by age. Further investigation into this relationship is important because of its potential clinical impact.

Meta-analysis of dietary glycemic load and glycemic index in relation to risk of coronary heart disease

A high glycemic diet may increase cardiovascular risk, yet whether the risk differs by gender or adiposity is inconclusive. Our goal was to determine the associations between dietary glycemic load (GL) and glycemic index (GI), and coronary heart disease (CHD) risk by conducting a meta-analysis of prospective studies. We searched the PubMed and Embase databases in July 2011 to identify eligible studies. The random-effects model was used to calculate pooled relative risks (RRs) comparing the highest categories of exposure to the lowest. Prespecified subgroup analyses were performed by gender and body mass index. We identified 8 prospective studies for meta-analysis, consisting of 220,050 participants and 4,826 incident CHD cases. Pooled RRs of CHD in relation to dietary GL were 1.08 (95% confidence interval [CI] 0.92 to 1.27) for men, 1.69 (95% CI 1.32 to 2.16) for women, and 1.36 (95% CI 1.13 to 1.63) for men and women combined. For dietary GI, corresponding pooled RRs were 0.99 (95% CI 0.84 to 1.16), 1.26 (95% CI 1.12 to 1.43), and 1.13 (95% CI 1.00 to 1.28), respectively. Limited evidence suggested the associations appeared more evident in the overweight and obese. There was no indication of publication bias. In conclusion, high dietary GL and GI significantly increased the risk of CHD in women but not in men, and the unfavorable effects may be more pronounced in overweight and obese patients. Further studies are needed to verify these findings and elucidate the underlying mechanisms.

Dietary glycemic load and glycemic index and risk of coronary heart disease and stroke in Dutch men and women: the EPIC-MORGEN study

BACKGROUND

The associations of glycemic load (GL) and glycemic index (GI) with the risk of cardiovascular diseases (CVD) are not well-established, particularly in men, and may be modified by gender.

OBJECTIVE

To assess whether high dietary GL and GI increase the risk of CVD in men and women.

METHODS

A large prospective cohort study (EPIC-MORGEN) was conducted within the general Dutch population among 8,855 men and 10,753 women, aged 21-64 years at baseline (1993-1997) and free of diabetes and CVD. Dietary intake was assessed with a validated food-frequency questionnaire and GI and GL were calculated using Foster-Powell's international table of GI. Information on morbidity and mortality was obtained through linkage with national registries. Cox proportional hazards analysis was performed to estimate hazard ratios (HRs) for incident coronary heart disease (CHD) and stroke, while adjusting for age, CVD risk factors, and dietary factors.

RESULTS

During a mean follow-up of 11.9 years, 581 CHD cases and 120 stroke cases occurred among men, and 300 CHD cases and 109 stroke cases occurred among women. In men, GL was associated with an increased CHD risk (adjusted HR per SD increase, 1.17 [95% CI, 1.02-1.35]), while no significant association was found in women (1.09 [0.89-1.33]). GI was not associated with CHD risk in both genders, while it was associated with increased stroke risk in men (1.27 [1.02-1.58]) but not in women (0.96 [0.75-1.22]). Similarly, total carbohydrate intake and starch intake were associated with a higher CHD risk in men (1.23 [1.04-1.46]; and 1.24 [1.07-1.45]), but not in women.

CONCLUSION

Among men, high GL and GI, and high carbohydrate and starch intake, were associated with increased risk of CVD.

Meta-analysis of studies of a specific delivery mode for a modified-carbohydrate diet

BACKGROUND

Obesity is highly prevalent throughout the world. Although modified-carbohydrate diets (MCDs) comprise one popular approach, questions remain about their utility for weight loss. The objective of the present study was to conduct a meta-analysis of randomised controlled trials (RCTs) of a specific MCD compared with various control diets on weight loss.

METHODS

Data from four RCTs (three obtained from the sponsor and one indentified through literature searches) were included. Intent-to-treat analyses were conducted using multiple imputation to handle missing data, where possible. Because inter-study heterogeneity was demonstrated with fixed-effects meta-analysis, a random-effects meta-analysis also was conducted.

RESULTS

When considered separately, all four studies showed greater reduction in body weight with the MCD compared to control diets at 12-week follow-up; the results at 24 weeks (available for three of the studies) were not as consistent. Results for body mass index (BMI) were similar. Greater reductions in waist circumference with the MCD were seen at either time point in only one study. When fixed-effects meta-analysis was applied, significantly greater reductions in weight, BMI and waist circumference with the MCD at both 12 weeks (1.66 kg, 0.53 kg m(-2) and 1.02 cm, respectively) and 24 weeks (1.20 kg, 0.43 kg m(-2) and 0.69 cm, respectively) were evident. Random-effects meta-analysis revealed similar results; however, the 24-week difference for a reduction in waist circumference was no longer statistically significant.

CONCLUSIONS

Meta-analysis of individual RCT results demonstrated consistent benefits of this MCD compared to control diets on weight loss up to 24 weeks and waist circumference up to 12 weeks.

Incorporation of whole, ancient grains into a modern Asian Indian diet to reduce the burden of chronic disease

Refined carbohydrates, such as white rice and white flour, are the mainstay of the modern Asian Indian diet, and may contribute to the rising incidence of type 2 diabetes and cardiovascular disease in this population. Prior to the 1950s, whole grains such as amaranth, barley, brown rice, millet, and sorghum were more commonly used in Asian Indian cooking. These grains and other non-Indian grains such as couscous, quinoa, and spelt are nutritionally advantageous and may be culturally acceptable carbohydrate substitutes for Asian Indians. This review focuses on practical recommendations for culturally sensitive carbohydrate modification in a modern Asian Indian diet to reduce type 2 diabetes and cardiovascular disease in this population.

Glycemic index differences of high-fat diets modulate primarily lipid metabolism in murine adipose tissue

A low vs. high glycemic index of a high-fat (HF) diet (LGI and HGI, respectively) significantly retarded adverse health effects in adult male C57BL/6J mice, as shown recently (Van Schothorst EM, Bunschoten A, Schrauwen P, Mensink RP, Keijer J. FASEB J 23: 1092–1101, 2009). The LGI diet enhanced whole body insulin sensitivity and repressed HF diet-induced body and white adipose tissue (WAT) weight gain, resulting in significantly reduced serum leptin and resistin levels and increased adiponectin levels. We questioned how WAT is modulated and characterized the molecular mechanisms underlying the glycemic index-mediated effects using whole genome microarrays. This showed that the LGI diet mainly exerts its beneficial effects via substrate metabolism, especially fatty acid metabolism. In addition, cell adhesion and cytoskeleton remodeling showed reduced expression, in line with lower WAT mass. An important transcription factor showing enhanced expression is PPAR-γ. Furthermore, serum levels of triglycerides, total cholesterol, and HDL- and LDL-cholesterol were all significantly reduced by LGI diet, and simultaneously muscle insulin sensitivity was significantly increased as analyzed by protein kinase B/Akt phosphorylation. Cumulatively, even though these mice were fed an HF diet, the LGI diet induced significantly favorable changes in metabolism in WAT. These effects suggest a partial overlap with pharmacological approaches by thiazolidinediones to treat insulin resistance and statins for hypercholesterolemia. It is therefore tempting to speculate that such a dietary approach might beneficially support pharmacological treatment of insulin resistance or hypercholesterolemia in humans.

Decreases in dietary glycemic index are related to weight loss among individuals following therapeutic diets for type 2 diabetes

This study assessed the effect of changes in glycemic index (GI) and load (GL) on weight loss and glycated hemoglobin (HbA1c) among individuals with type 2 diabetes beginning a vegan diet or diet following the 2003 American Diabetes Association (ADA) recommendations. The study was a 22-wk, randomized trial of 99 participants with type 2 diabetes who were counseled to follow 1 of 2 diet treatments. GI and GL changes were assessed based on 3-d dietary records. The relationships between GI/GL and changes in weight and HbA1C were calculated. In an intention-to-treat analysis (n = 99), the vegan group reduced GI to a greater extent than the ADA group (P < 0.05), but GL was reduced further in the ADA than the vegan group (P < 0.001). GI predicted changes in weight (P = 0.001), adjusting for changes in fiber, carbohydrate, fat, alcohol, energy intake, steps per day, group, and demographics, such that for every point decrease in GI, participants lost ~0.2 kg (0.44 lb). GI was not a predictor for changes in HbA1C after controlling for weight loss (P = 0.33). Weight loss was a predictor of changes in HbA1C (P = 0.047). GL was not related to weight loss or changes in HbA1C. A low-GI diet appears to be one of the determinants of success of a vegan or ADA diet in reducing body weight among people with type 2 diabetes. The reduction of body weight, in turn, was predictive of decreasing HbA1C.

Targeting dietary fat or glycemic load in the treatment of obesity and type 2 diabetes: a randomized controlled trial

AIMS

To compare the effects of lifestyle modification programs that prescribe low-glycemic load (GL) vs. low-fat diets in a randomized trial.

METHODS

Seventy-nine obese adults with type 2 diabetes received low-fat or low-GL dietary instruction, delivered in 40-week lifestyle modification programs with identical goals for calorie intake and physical activity. Changes in weight, HbA(1c), and other metabolic parameters were compared at weeks 20 and 40.

RESULTS

Weight loss did not differ between groups at week 20 (low-fat: -5.7±3.7%; low-GL: -6.7±4.4%, p=.26) or week 40 (low-fat: -4.5±7.5%; low-GL: -6.4±8.2%, p=.28). Adjusting for changes in antidiabetic medications, subjects on the low-GL diet had larger reductions in HbA(1c) than those on the low-fat diet at week 20 (low-fat: -0.3±0.6%; low-GL: -0.7±0.6%, p=.01), and week 40 (low-fat: -0.1±1.2%; low-GL: -0.8±1.3%; p=.01). Groups did not differ significantly on any other metabolic outcomes (p≥.06).

CONCLUSIONS

Results suggest that targeting GL, rather than dietary fat, in a low-calorie diet can significantly enhance the effect of weight loss on HbA(1c) in patients with type 2 diabetes.

Program adherence and effectiveness of a commercial nutrition program: the metabolic balance study

Objective. To assess the effectiveness of a commercial nutrition program in improving weight, blood lipids, and health-related quality of life (HRQOL). Methods. Prospective observational study with followup after 1, 3, 6, and 12 months with data from questionnaires and blood samples. Subjects. After 12 months, we had data from 524 subjects (= 60.6% of the initial samples). 84.1% of the subjects were women. The average BMI at baseline was 30.3 (SD = 5.7). Results. After 12 months, the average weight loss was 6.8 kg (SD = 7.1 kg). Program adherence declined over time but was still high after 12 months and showed a positive linear correlation with weight loss. Relevant blood parameters as well as HRQOL improved significantly. Conclusion. After 12 months, nearly two thirds of the samples had achieved >5% reduction of their initial weights. The high degree of program adherence is probably due to personal counseling and individually designed nutrition plans provided by the program.

Low glycemic diet for weight loss in hypertriglyceridemic patients attending a lipid clinic

PURPOSE

To assess the effectiveness of low glycemic dietary counseling for weight loss among moderately hypertriglyceridemic patients in an academic referral lipid clinic.

METHODS

During 1998 to 2000, weight loss advice followed traditional guidelines. Beginning in 2001, hypertriglyceridemic patients were advised to greatly reduce intake of high glycemic carbohydrates. The clinic database was queried for all patients initiating consultative treatment from 1998 through 2004. Subjects were included if initial fasting triglyceride was 200 to 800 mg/dL and if at least two follow-up visits were made during a period of 365 days or more. Mean percent changes from baseline in weight and lipid/lipoproteins beyond 1 year were calculated. Macronutrient composition was determined 3- to 5-day food diaries submitted by subjects from the highest quartile of weight loss.

RESULTS

Patients (n = 56) first seen in 1998-2000 had 0.2 ± 0.7% mean weight gain beyond one year compared with 3.0 ± 0.5% weight loss for patients (n = 141) initially seen in 2001 to 2004 (P < .001 comparing groups). Weight loss correlated with triglyceride reduction (-2.6 mg/dL per kilogram body weight, r = 0.29, P < .001) and with HDL-C increase (0.22 mg/dL per kilogram body weight, r = 0.16; P = .038). Highest quartile weight losers in the low glycemic group (n = 15) reported consuming 44% carbohydrate calories, 32% fat, 22% protein, and 2% alcohol.

CONCLUSION

Hypertriglyceridemic patients who received low glycemic dietary counseling and maintained clinic attendance more than 1 year achieved mean 3.0% weight loss. This was improved compared with historical controls with traditional dietary counseling. Food diaries from successful weight losers suggested compliance with a low glycemic, moderately reduced carbohydrate diet plan.

A high legume low glycemic index diet improves serum lipid profiles in men

Clinical studies have shown that fiber consumption facilitates weight loss and improves lipid profiles; however, the beneficial effects of high fermentable fiber low glycemic index (GI) diets under conditions of weight maintenance are unclear. In the Legume Inflammation Feeding Experiment, a randomized controlled cross-over feeding study, 64 middle-aged men who had undergone colonoscopies within the previous 2 years received both a healthy American (HA) diet (no legume consumption, fiber consumption = 9 g/1,000 kcal, and GI = 69) and a legume enriched (1.5 servings/1,000 kcal), high fiber (21 g/1,000 kcal), low GI (GI = 38) diet (LG) in random order. Diets were isocaloric and controlled for macronutrients including saturated fat; they were consumed each for 4 weeks with a 2-4 week break separating dietary treatments. Compared to the HA diet, the LG diet led to greater declines in both fasting serum total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C) (P < 0.001 and P < 0.01, respectively). Insulin-resistant (IR) subjects had greater reductions in high density lipoprotein cholesterol (HDL-C; P < 0.01), and triglycerides (TAG)/HDL-C (P = 0.02) after the LG diet, compared to the HA diet. Insulin-sensitive (IS) subjects had greater reductions in TC (P < 0.001), LDL-C (P < 0.01), TC/HDL-C (P < 0.01), and LDL-C/HDL-C (P = 0.02) after the LG diet, compared to the HA diet. In conclusion, a high legume, high fiber, low GI diet improves serum lipid profiles in men, compared to a healthy American diet. However, IR individuals do not achieve the full benefits of the same diet on cardiovascular disease (CVD) lipid risk factors.

The glycemic index: physiological significance

The glycemic index (GI) is a physiological assessment of a food's carbohydrate content through its effect on postprandial blood glucose concentrations. Evidence from trials and observational studies suggests that this physiological classification may have relevance to those chronic Western diseases associated with overconsumption and inactivity leading to central obesity and insulin resistance. The glycemic index classification of foods has been used as a tool to assess potential prevention and treatment strategies for diseases where glycemic control is of importance, such as diabetes. Low GI diets have also been reported to improve the serum lipid profile, reduce C-reactive protein (CRP) concentrations, and aid in weight control. In cross-sectional studies, low GI or glycemic load diets (mean GI multiplied by total carbohydrate) have been associated with higher levels of high-density lipoprotein cholesterol (HDL-C), with reduced CRP concentrations, and, in cohort studies, with decreased risk of developing diabetes and cardiovascular disease. In addition, some case-control and cohort studies have found positive associations between dietary GI and risk of various cancers, including those of the colon, breast, and prostate. Although inconsistencies in the current findings still need to be resolved, sufficient positive evidence, especially with respect to renewed interest in postprandial events, suggests that the glycemic index may have a role to play in the treatment and prevention of chronic diseases.

Low-fat dietary pattern and lipoprotein risk factors: the Women's Health Initiative Dietary Modification Trial

BACKGROUND

The Women's Health Initiative Dietary Modification Trial tested the effects on chronic disease of a dietary pattern lower in fat and higher in vegetables, fruit, and grains.

OBJECTIVE

The objective was to evaluate the effects of dietary carbohydrate changes on lipids and lipoprotein composition.

DESIGN

Postmenopausal women were randomly assigned to an intervention or a comparison group for a mean of 8.1 y. Lipoprotein analyses and subclasses were based on subsamples of 2730 and 209 participants, respectively.

RESULTS

At year 6, the total reported fat intake was 7.8% lower and carbohydrate intake was 7.6% higher in the intervention group than in the comparison group. Triglyceride change between groups differed by 2.3, 3.8, and -0.8 mg/dL at 1, 3, and 6 y, respectively, and HDL-cholesterol change differed by -1.6, -0.7, and -1.0 mg/dL at 1, 3, and 6 y, respectively. Changes did not differ by age, ethnicity, or obesity. In diabetic intervention women who were white, the triglyceride difference between the intervention and comparison groups was 33.8 mg/dL, whereas in black women with diabetes (n = 50 in the intervention group; n = 83 in the comparison group), the triglyceride difference was 6.4 mg/dL (P for 3-factor interaction = 0.049). No significant changes were observed in apolipoprotein or lipoprotein particles. Reductions in LDL cholesterol varied by quartile of reported lowering of saturated or trans fat.

CONCLUSIONS

The replacement of 7-8% of fat intake with complex carbohydrates over 6 y was not associated with clinically adverse effects on triglycerides, HDL cholesterol, or lipoprotein subclasses. Diabetic white women with higher triglyceride concentrations may have greater increases in triglycerides.

Dietary glycemic index, dietary glycemic load, and incidence of heart failure events: a prospective study of middle-aged and elderly women

OBJECTIVE

Dietary glycemic index (GI) and glycemic load (GL), measures of the propensity of dietary carbohydrate to increase blood glucose, have been associated with risk of coronary heart disease, but their association with incidence of heart failure (HF) is unknown. The authors therefore assessed whether dietary GI and GL were associated with rates of HF events.

METHODS

The authors conducted a prospective, observational study of 36,019 women 48-83 years old without baseline HF, diabetes, or myocardial infarction who were participants in the Swedish Mammography Cohort, a prospective cohort study. Diet was measured using food-frequency questionnaires. Women were followed from January 1, 1998, through December 31, 2006, for HF hospitalization or death through the Swedish inpatient and cause-of-death registers. Cox proportional hazards models adjusted for age and other risk factors were used to estimate incidence rate ratios (RRs) and 95% confidence intervals (CIs).

RESULTS

Over 9 years of follow-up, 639 of 36,019 women died of HF (n = 54) or were hospitalized for HF for the first time (n = 585). The authors did not find statistically significant associations between dietary GI and HF events (RR comparing highest to lowest quartile = 1.12, 95% CI = 0.87-1.45, p for trend = 0.31) or between dietary GL and HF events (RR comparing highest to lowest quartile = 1.30, 95% CI = 0.87-1.93, p for trend = 0.16). Results were not significantly different in normal weight and overweight women.

CONCLUSIONS

In this population, dietary GI did not appear to be associated with incident HF events. There was a suggestion of an association between dietary GL and HF, which did not reach statistical significance.

Association of glycemic load with cardiovascular disease risk factors: the Women's Health Initiative Observational Study

OBJECTIVE

Associations between dietary glycemic load (GL) and cardiovascular disease risk factors, including plasma lipoprotein/lipid levels, blood pressure, and glucose metabolism factors, in the Women's Health Initiative Observational Study were examined.

METHODS

A random sample of 878 Observational Study participants (postmenopausal women 50-79 y of age) with baseline blood measurements (647 white, 104 black, 127 Hispanic) was included. Dietary GL was estimated from baseline food-frequency questionnaires, which assessed dietary intake over the previous 3 mo. At the baseline visit, participants completed demographic and health habit questionnaires, fasting blood samples were collected, anthropometric measurements were completed, and blood pressure was assessed.

RESULTS

In all participants combined, GL was inversely associated with high-density lipoprotein cholesterol (P for trend = 0.004) and positively associated with log(10)-transformed triacylglycerols (P = 0.008). Although there were no statistically significant interactions of race/ethnicity with associations between GL and cardiovascular disease risk factors, stratified results were suggestive, showing that GL was positively associated with total cholesterol (P = 0.018) and low-density lipoprotein cholesterol (P = 0.038) in Hispanics. In white subjects, there was a trend of reduced high-density lipoprotein cholesterol with higher GL (P = 0.003), whereas GL was positively associated with log(10)-transformed triacylglycerols (P = 0.015). Associations between GL and high-density lipoprotein cholesterol and between GL and triacylglycerols also differed by body mass index, although the interactions were not statistically significant.

CONCLUSION

Among these generally healthy postmenopausal women, GL was associated with high-density lipoprotein cholesterol and triacylglycerols. Suggestive effects of race/ethnicity and body mass index on these associations need to be confirmed in larger studies.