Search

An influential 2-wk cross-over feeding trial without a washout period purported to show advantages of a low-fat diet (LFD) compared with a low-carbohydrate diet (LCD) for weight control. In contrast to several other macronutrient trials, the diet order effect was originally reported as not significant. In light of a new analysis by the original investigative group identifying an order effect, we aimed to examine, in a reanalysis of publicly available data (16 of 20 original participants; 7 female; mean BMI, 27.8 kg/m 2 ), the validity of the original results and the claims that trial data oppose the carbohydrate-insulin model of obesity (CIM). We found that energy intake on the LCD was much lower when this diet was consumed first compared with second (a difference of -1164 kcal/d, P = 3.6 × 10 -13 ); the opposite pattern was observed for the LFD (924 kcal/d, P = 2.0 × 10 -16 ). This carry-over effect was significant (P interaction = 0.0004) whereas the net dietary effect was not (P = 0.4). Likewise, the between-arm difference (LCD - LFD) was -320 kcal/d in the first period and +1771 kcal/d in the second. Body fat decreased with consumption of the LCD first and increased with consumption of this diet second (-0.69 ± 0.33 compared with 0.57 ± 0.32 kg, P = 0.007). LCD-first participants had higher β-hydroxybutyrate levels while consuming the LCD and lower respiratory quotients while consuming LFD when compared with LFD-first participants on their respective diets. Change in insulin secretion as assessed by C-peptide in the first diet period predicted higher energy intake and less fat loss in the second period. These findings, which tend to support rather than oppose the CIM, suggest that differential (unequal) carry-over effects and short duration, with no washout period, preclude causal inferences regarding chronic macronutrient effects from this trial., (Copyright © 2023 The Author(s). Published by Elsevier Inc. All rights reserved.)

Background: The Diet Intervention Examining The Factors Interacting with Treatment Success (DIETFITS) trial demonstrated that meaningful weight loss can be achieved with either a "healthy low-carbohydrate diet" (LCD) or "healthy low-fat diet" (LFD). However, because both diets substantially decreased glycemic load (GL), the dietary factors mediating weight loss remain unclear., Objectives: We aimed to explore the contribution of macronutrients and GL to weight loss in DIETFITS and examine a hypothesized relationship between GL and insulin secretion., Design: This study is a secondary data analysis of the DIETFITS trial, in which participants with overweight or obesity (aged 18-50 y) were randomized to a 12-mo LCD (N = 304) or LFD (N = 305)., Results: Measures related to carbohydrate intake (total amount, glycemic index, added sugar, and fiber) showed strong associations with weight loss at 3-, 6-, and 12-mo time points in the full cohort, whereas those related to total fat intake showed weak to no associations. A biomarker of carbohydrate (triglyceride/HDL cholesterol ratio) predicted weight loss at all time points (3-mo: β [kg/biomarker z-score change] = 1.1, P = 3.5 × 10 -9 ; 6-mo: β = 1.7, P = 1.1 × 10 -9 ; and 12-mo: β = 2.6, P = 1.5 × 10 -15 ), whereas that of fat (low-density lipoprotein cholesterol + HDL cholesterol) did not (all time points: P = NS). In a mediation model, GL explained most of the observed effect of total calorie intake on weight change. Dividing the cohort into quintiles of baseline insulin secretion and GL reduction revealed evidence of effect modification for weight loss, with P = 0.0009 at 3 mo, P = 0.01 at 6 mo, and P = 0.07 at 12 mo., Conclusions: As predicted by the carbohydrate-insulin model of obesity, weight loss in both diet groups of DIETFITS seems to have been driven by the reduction of GL more so than dietary fat or calories, an effect that may be most pronounced among those with high insulin secretion. These findings should be interpreted cautiously in view of the exploratory nature of this study., Trial Registration: ClinicalTrials.gov (NCT01826591)., (Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved.)

Purpose: This study describes the association between frequency of bicycling for active transportation and modifiable cardiometabolic risk factors in the Minneapolis-Saint Paul (MSP) metropolitan area., Design: We conducted an online survey from a convenience sample of likely bicycle commuters., Setting: Participants were e-mailed invitations including a link to the online survey., Participants: Participants (n = 1450, 15.6% response rate) were residents of the 7-county MSP metropolitan area aged 20 to 64 years., Measures: Participants reported frequency of commute and destination cycling from April to September and October to March, prevalent cardiometabolic risk factors, and demographic covariates., Analysis: We performed logistic regressions for associations between average weekly transportation bicycling and self-reported prevalent obesity, high blood pressure, high cholesterol, low high-density lipoprotein cholesterol, and high triglycerides. We used Poisson regression for the count of cardiometabolic risk factors. All models were adjusted for age, sex, race, smoking, alcohol consumption, and other physical activity, with random intercepts by zip code., Results: Self-reported bicycling frequency is associated with significantly lower odds of prevalent obesity, hypertension, and high triglycerides. Three bicycling trips per week is associated with 20% fewer (95% confidence interval: 12%-28%) cardiometabolic risk factors., Conclusion: Bicycling frequency is inversely associated with cardiometabolic risk factors. These results provide empirical support for the promotion of active transportation as public health policy.

Background: Inverse associations between dairy intake and the risk of type 2 diabetes have been shown, but more studies are needed, especially from low- and middle-income countries., Objective: The objective was to describe the association between dairy products and direct measures of glycemic status in adults without known diabetes., Design: The Brazilian Longitudinal Study of Adult Health (ELSA-Brasil) includes 15,105 adults, aged 35-74 y, enrolled from universities and research institutions in 6 Brazilian capital cities. We excluded participants with a known diabetes diagnosis, cardiovascular diseases, and cancer. Dairy consumption was assessed by a food-frequency questionnaire, and we computed servings per day for total and subgroups of dairy. Associations with fasting blood glucose (FG) and fasting insulin, 2-h postload glucose (PG), 2-h postload insulin (PI), glycated hemoglobin (Hb A1c), and homeostasis model assessment of insulin resistance (HOMA-IR) were assessed through multivariable linear regression analysis with adjustment for demographic characteristics, behavioral risk factors, other dietary factors, and anthropometric measurements., Results: The sample size after exclusions was 10,010. The intake of total dairy was inversely associated with FG (linear β for dairy servings/d = -0.46 ± 0.2 mg/dL), PG (-1.25 ± 0.5 mg/dL), PI (-1.52 ± 0.6 mg/dL), Hb A1c (-0.02 ± 0.0%), and HOMA-IR (-0.04 ± 0.0) after adjustment for all covariates (P < 0.05 for all). The findings were consistent across categories of sex, race, obesity status, and dairy fat amount (reduced-fat vs. full-fat dairy). Fermented dairy products showed particularly strong inverse associations with the outcomes, with adjusted differences for a 1-serving/d increment of -0.24 (95% CI: -0.46, -0.02) mg/dL for FG, -0.86 (-1.42, -0.30) mg/dL for PG, and -0.01% (-0.02%, 0.00%) for Hb A1c. Myristic acid was the only nutrient that appeared to mediate the association between dairy intake and glycemia., Conclusion: Dairy intake, especially fermented dairy, was inversely associated with measures of glycemia and insulinemia in Brazilian adults without diagnosed diabetes. This trial was registered at clinicaltrials.com as NCT02320461., (© 2015 American Society for Nutrition.)

The goal of this review was to critically evaluate the scientific evidence in humans on the potential effect of sweetened beverages on weight gain and risk of obesity in youth and adults. Two categories of these beverages were reviewed. Sugar-sweetened beverages (SSBs) include soft drinks, colas, other sweetened carbonated beverages, and fruit drinks with added sugar. Artificially sweetened beverages (ASBs), also referred to as non-nutritive sweetened beverages, are marketed and used as a replacement for SSBs for those who want to reduce sugar and caloric intake. The totality of evidence to date demonstrates a pattern across observational and experimental studies of an increased risk of weight gain and obesity with higher intake of SSBs. However, it remains difficult to establish the strength of the association and the independence from other potentially confounding factors. The primary reason for unclear conclusions regarding the robustness of any effect of SSBs is due to the heterogeneity and methodologic limitations of both observational and experimental studies on this topic. Although some observational studies have suggested that ASBs may cause increased risk of obesity and cardiometabolic diseases, there is no clear mechanism for this pathway, and the epidemiologic studies are highly inconsistent. An important issue with the observational studies on ASBs and obesity or disease risk is reverse causality bias, with higher-quality studies demonstrating this possibility. The field needs higher-quality experimental studies in humans, with relevant direct comparisons between sweetened beverages and their sweetened solid-food alternatives., (© 2014 American Society for Nutrition.)

"Diet beverage" is a common term used to describe beverages that are sweetened with non-nutritive or artificial sweeteners (ASBs). Marketing strategies often imply that consuming these beverages holds promise for weight control or weight loss. The objective of the present review is to provide a synthesis of the literature on the effects of ASBs on body weight, cardiovascular disease, and type 2 diabetes. Consumption of diet beverages is much lower than that of sugar-sweetened beverages (SSBs), and people trying to lose weight report the highest levels of ASB consumption. To date, prospective observational studies have revealed mixed results, and it appears that reverse causality is a particular problem, since individuals who are at higher risk for weight gain may choose to consume ASBs in an attempt to control their weight or reduce disease risk. As for experimental studies, the evidence currently suggests that obesity risk may be lower when ASBs replace SSBs in the diet. Still, additional evidence from experimental studies is needed to more definitively determine the benefits and risks of frequent ASB consumption., (© 2013 International Life Sciences Institute.)

Objective: To compare BMI with abdominal skinfold thickness (ASF), waist circumference and waist-to-height ratio in the prediction of insulin resistance (IR) in prepubertal Colombian children., Design: We calculated age- and sex-specific Z-scores for BMI, ASF, waist circumference, waist-to-height ratio and three other skinfold-thickness sites. Logistic regression with stepwise selection (P = 0·80 for entry and P = 0·05 for retention) was performed to identify predictors of IR and extreme IR, which were determined by age- and sex-specific Z-scores to identify the ≥ 90th and ≥ 95th percentile of homeostasis model assessment (HOMAIR), respectively. We used receiver operating characteristic curves to compare the area under the curve between models., Setting: Bucaramanga, Colombia., Subjects: Children (n 1261) aged 6-10 years in Tanner stage 1 from a population-based study., Results: A total of 127 children (seventy girls and fifty-seven boys) were classified with IR, including sixty-three children (thirty-three girls and thirty boys) classified with extreme IR. Only ASF and BMI Z-scores were retained as predictors of IR by stepwise selection. Adding ASF Z-score to BMI Z-score improved the area under the curve from 0·794 (95 % CI 0·752, 0·837) to 0·811 (95 % CI 0·770, 0·851; P for contrast = 0·01). In predicting extreme IR, the addition of ASF Z-score to BMI Z-score improved the area under the curve from 0·837 (95 % CI 0·790, 0·884) to 0·864 (95 % CI 0·823, 0·905; P for contrast = 0·01)., Conclusions: ASF Z-score predicted IR independent of BMI Z-score in our population of prepubertal children. ASF and BMI Z-scores together improved IR risk stratification compared with BMI Z-score alone, opening new perspectives in the prediction of cardiometabolic risk in prepubertal children.

Certain aspects of the home environment as well as individuals' knowledge of energy balance are believed to be important correlates of various dietary and physical activity behaviors, but no known studies have examined potential relationships between these correlates. This study evaluated cross-sectional associations between characteristics of the home environment and energy balance knowledge among 349 youth/parent pairs recruited from the Minneapolis/St Paul, MN, metropolitan area from September 2006 to June 2007. Linear regression models adjusted for student grade and highest level of parental education were used to compare data from home food, physical activity, and media inventories (parent-reported) with energy balance knowledge scores from youth and parent questionnaires. Paired energy balance knowledge (average of youth and parent knowledge scores) was associated with all home food availability variables. Paired knowledge was also significantly associated with a media equipment availability and accessibility summary score (β=-1.40, P=0.005), as well as an activity-to-media ratio score (β=0.72, P=0.003). Youth and/or parent knowledge alone was not significantly associated with most characteristics of the home environment, supporting the importance of developing intervention strategies that target the family as a whole., (Copyright © 2011 American Dietetic Association. Published by Elsevier Inc. All rights reserved.)

Objectives: The health effects of added sugars have received much attention, but few studies have examined the association between foods that naturally contain sugar, such as 100% fruit juice, and risk of obesity and related conditions. Therefore, our purpose was to study the association between 100% fruit juice intake and risk of obesity and metabolic syndrome in a representative sample of the U.S. population., Methods: Cross-sectional analysis of a multiethnic sample of U.S. adults from the National Health and Nutrition Examination Survey 1999-2004 was undertaken to examine the association between 100% fruit juice consumption and the odds of obesity (body mass index [BMI] ≥ 30 kg/m2) and metabolic syndrome (Adult Treatment Panel [ATP] III definition). We used logistic regression analysis to estimate the odds of obesity and metabolic syndrome per category of fruit juice consumption exposure, while adjusting for covariates that may be confounders of this association., Results: Of 14,196 adults included in the sample, 3961 were consumers of fruit juice. Consumers of 100% fruit juice, relative to nonconsumers, had lower mean BMI, lower waist circumference, and lower homeostasis model assessment (HOMA) insulin resistance (p < 0.001). Level of intake (oz/d) had a linear inverse association with HOMA (p < 0.001), whereas the association with BMI and waist circumference was U-shaped (p < 0.001). Consumers relative to nonconsumers had 22% (95% confidence interval [CI] = 13%-30%) lower odds of obesity and 15% (95% CI = 10%-28%) lower odds of metabolic syndrome. After adjustment for demographics and lifestyle factors, the lower odds of obesity remained statistically significant, but a statistically significant reduction in odds of metabolic syndrome was no longer noted., Conclusions: Compared with nonconsumers, those who consumed 100% fruit juice were leaner, were more insulin sensitive, and had lower odds of obesity and metabolic syndrome. The association with metabolic syndrome was explained primarily by other lifestyle factors, while the association with obesity remained independent. Experimental studies are needed to determine whether any direct physiologic link exists between consumption of 100% fruit juice and lower risks for obesity and metabolic syndrome.

Background: The optimal range of relative weight for morbidity and mortality in Asian populations is an important question in need of more thorough investigation, especially as obesity rates increase. We aimed to examine the association between body mass index (BMI), all cause and cause-specific mortality to determine the optimal range of BMI in relation to mortality in Chinese men and women in Singapore., Methodology/principal Findings: We analyzed data from a prospective cohort study of 51,251 middle-aged or older (45-74) Chinese men and women in the Singapore Chinese Health Study. Participants were enrolled and data on body weight and covariates were collected in 1993-1998 and participants were followed through 2008. The analysis accounted for potential methodological issues through stratification on smoking and age, thorough adjustment of demographic and lifestyle confounders and exclusion of deaths early in the follow-up., Conclusions/significance: Increased risk of mortality was apparent in underweight (<18.5) and obese BMI categories (≥27.5) independent of age and smoking. Regardless of age or BMI, smoking considerably increased the rate of mortality and modified the association between BMI and mortality. The most favorable range of BMI for mortality rates and risk in non-smoking persons below age 65 was 18.5-21.4 kg/m(2), and for non-smoking persons aged 65 and above was 21.5-24.4 kg/m(2).

Background: Public parks are increasingly recognized as important places that facilitate physical activity. Despite the presence of parks, constraints to recreation and physical activity at parks exist. As the health benefits identified with physical activity require long-term and regular activity, it is important to examine factors pertaining to physical activity participation beyond initiation. This study explored differences in reported constraints to park based physical activity and negotiation strategies by physical activity stage of change., Methods: Data were collected among visitors to one Minnesota state park via onsite and follow-up questionnaires., Results: The average visitor had a healthier weight than the average U.S. and Minnesota adult and the majority of visitors were meeting the physical activity recommendations (86.4%). Respondents in the inactive/insufficient stages were more constrained and used fewer negotiation strategies than respondents in the maintenance stage., Conclusions: Results both support and expand on previous research findings. Specifically, this study supports research which indicates the adoption and maintenance of physical activity are influenced by different individual, social and environmental factors, and expands the research base by examining constraints and negotiation at different physical activity stages in a park setting. Implications of these findings provide directions for future stage-based intervention efforts.

Background: Childhood obesity is a major risk factor for adult obesity, and obese children tend to be taller than their normal-weight peers., Purpose: The aim of this study is to evaluate whether childhood height influences the probability that normal or overweight children become overweight young adults., Methods: The study involved a multicenter prospective cohort of subjects assessed in both third grade and 12th grade, n=2802. Main exposures were CDC childhood BMI categories and height quartiles from third-grade measurements. Main outcome measure was CDC adult BMI categories from 12th-grade measurements. Associations between childhood height quartiles, childhood BMI categories, and adult BMI categories were assessed using chi-square tests and logistic regression models., Results: Overall, 79% of overweight children remained overweight as young adults. Among children who were overweight or obese, the probability of becoming an overweight or obese young adult was 85% for children in the top quartile of height and 67% for children in the bottom quartile of height (p=0.007). Among children who were normal weight, the probability of becoming an overweight or obese young adult was 25% for children in the top height quartile versus 17% for children in the bottom height quartile (p=0.003)., Conclusions: When clinicians classify children by BMI categories and counsel about the risk for future obesity, they should recognize that greater height may be a marker for increased risk of adult overweight and obesity., (2010 American Journal of Preventive Medicine. Published by Elsevier Inc. All rights reserved.)

The purpose of this study was to examine the interaction of childhood height and childhood BMI in the prediction of young adult BMI. The 2,802 subjects in this study were from the Child and Adolescent Trial for Cardiovascular Health (CATCH). The subjects' heights and weights were measured in 3rd grade (mean age 8.7 years) and again in 12th grade (mean age 18.3 years). The associations and interactions between height (cm) and BMI (kg/m(2)) were assessed using mixed linear regression models with adult BMI as the dependent variable. We found a significant interaction between childhood height and childhood BMI in the prediction of adult BMI (P < 0.0001). Stratification by Centers for Disease Control and Prevention (CDC) reference quintiles revealed that a positive association between childhood height and adult BMI existed only for those subjects in the top quintile of childhood BMI, within whom predicted adult BMI ranged from 27.5 (95% confidence interval = 26.4-28.6) for those in the shortest height quintile to 30.2 (95% confidence interval = 29.7-30.6) for those in the highest height quintile. Among children with high BMI levels, those who were taller, as compared to those who were shorter, had significantly higher young adult BMI levels. This pattern seems primarily due to the positive association of childhood height and childhood BMI. Clinicians should recognize the risk of excess body weight in young adulthood for all children who have a high BMI, and pay special attention to those who are tall, because their childhood height will not protect them from subsequent weight gain and elevated BMI.

The frequency of eating breakfast has declined over the past several decades, during which time the obesity epidemic has also unfolded. Therefore, there is growing scientific interest in the possible causal role of breakfast in weight control and related disease risks. We conducted a MedLine search for studies that addressed meal frequency, breakfast consumption, and chronic disease risk. Clinical studies document that regular meal consumption can potentially reduce the risk of obesity and chronic disease through mechanisms involved in energy balance and metabolism. Many observational studies have found that breakfast frequency is inversely associated with obesity and chronic disease, but this literature does have some important limitations. Only four relatively small and short-term randomized trials have examined breakfast consumption and body weight or chronic disease risk, with mixed results. Large, long-term, randomized trials are needed.

Context: Weight loss elicits physiological adaptations relating to energy intake and expenditure that antagonize ongoing weight loss., Objective: To test whether dietary composition affects the physiological adaptations to weight loss, as assessed by resting energy expenditure. DESIGN, STUDY, AND PARTICIPANTS: A randomized parallel-design study of 39 overweight or obese young adults aged 18 to 40 years who received an energy-restricted diet, either low-glycemic load or low-fat. Participants were studied in the General Clinical Research Centers of the Brigham and Women's Hospital and the Children's Hospital, Boston, Mass, before and after 10% weight loss. The study was conducted from January 4, 2001, to May 6, 2003., Main Outcome Measures: Resting energy expenditure measured in the fasting state by indirect calorimetry, body composition by dual-energy x-ray absorptiometry, cardiovascular disease risk factors, and self-reported hunger., Results: Resting energy expenditure decreased less with the low-glycemic load diet than with the low-fat diet, expressed in absolute terms (mean [SE], 96 [24] vs 176 [27] kcal/d; P = .04) or as a proportion (5.9% [1.5%] vs 10.6% [1.7%]; P = .05). Participants receiving the low-glycemic load diet reported less hunger than those receiving the low-fat diet (P = .04). Insulin resistance (P = .01), serum triglycerides (P = .01), C-reactive protein (P = .03), and blood pressure (P = .07 for both systolic and diastolic) improved more with the low-glycemic load diet. Changes in body composition (fat and lean mass) in both groups were very similar (P = .85 and P = .45, respectively)., Conclusions: Changes in dietary composition within prevailing norms can affect physiological adaptations that defend body weight. Reduction in glycemic load may aid in the prevention or treatment of obesity, cardiovascular disease, and diabetes mellitus.

Context: Fast food consumption has increased greatly among children in recent years, in tandem with the obesity epidemic. Fast food tends to promote a positive energy balance and, for this reason, may result in weight gain. However, if fast food and obesity are causally related, the question arises of why some children who frequently eat fast food do not become overweight., Objective: To test the hypothesis that overweight adolescents are more susceptible to the adverse effects of fast food than lean adolescents., Design and Setting: In study 1, we fed participants an "extra large" fast food meal in a naturalistic setting (a food court). The participants were instructed to eat as much or little as desired during this 1-hour meal. In study 2, we assessed energy intake under free-living conditions for 2 days when fast food was consumed and 2 days when it was not consumed. Data were collected in Boston, Mass, between July 2002 and March 2003., Participants: Overweight (n = 26) and lean (n = 28) adolescents aged 13 to 17 years. Overweight was defined as a body mass index exceeding sex- and age-specific 85th percentiles based on the 2000 Centers for Disease Control and Prevention growth charts., Main Outcome Measures: Energy intake determined by direct observation in study 1 and by unannounced 24-hour dietary recalls, administered by telephone, in study 2., Results: In study 1, mean (SEM) energy intake from the fast food meal among all participants was extremely large (1652 [87] kcal), accounting for 61.6% (2.2%) of estimated daily energy requirements. Overweight participants ate more than lean participants whether energy was expressed in absolute terms (1860 [129] vs 1458 [107] kcal, P =.02) or relative to estimated daily energy requirements (66.5% [3.1%] vs 57.0% [2.9%], P =.03). In study 2, overweight participants consumed significantly more total energy on fast food days than non-fast food days (2703 [226] vs 2295 [162] kcal/d; +409 [142] kcal/d; P =.02), an effect that was not observed among lean participants (2575 [157] vs 2622 [191] kcal/d; -47 [173] kcal/d; P =.76)., Conclusions: In this study, adolescents overconsumed fast food regardless of body weight, although this phenomenon was especially pronounced in overweight participants. Moreover, overweight adolescents were less likely to compensate for the energy in fast food, by adjusting energy intake throughout the day, than their lean counterparts.

Both intake of whole grain and higher levels of serum enterolactone have been related to reduced risk for CHD and some cancers. Because lignans are prevalent in the outer layers of grains, these findings may be related. We carried out a crossover feeding study in which overweight, hyperinsulinaemic, non-diabetic men (n 5) and women (n 6) ate, in random order, wholegrain foods or refined-grain foods in a diet with 30 % energy from fat. The dominant whole grain was wheat, followed by oats and rice. All food was supplied by the investigators and each diet lasted for 6 weeks, with an intervening washout period of 6-9 weeks. Serum enterolactone concentrations were higher when eating the wholegrain than the refined-grain diet by 6.2 (within person SE 1.7) nmol/l (P=0.0008). Most of the increase in serum enterolactone when eating the wholegrain diet occurred within 2 weeks, though the serum enterolactone difference between wholegrain and refined-grain diets continued to increase through 6 weeks. Serum enterolactone concentrations can be raised by eating a diet rich in whole grains.

Background: Epidemiologic studies have found whole-grain intake to be inversely associated with the risk of type 2 diabetes and heart disease., Objective: We tested the hypothesis that whole-grain consumption improves insulin sensitivity in overweight and obese adults., Design: This controlled experiment compared insulin sensitivity between diets (55% carbohydrate, 30% fat) including 6-10 servings/d of breakfast cereal, bread, rice, pasta, muffins, cookies, and snacks of either whole or refined grains. Total energy needs were estimated to maintain body weight. Eleven overweight or obese [body mass index (in kg/m(2)): 27-36] hyperinsulinemic adults aged 25-56 y participated in a randomized crossover design. At the end of each 6-wk diet period, the subjects consumed 355 mL (12 oz) of a liquid mixed meal, and blood samples were taken over 2 h. The next day a euglycemic hyperinsulinemic clamp test was administered., Results: Fasting insulin was 10% lower during consumption of the whole-grain than during consumption of the refined-grain diet (mean difference: -15 +/- 5.5 pmol/L; P = 0.03). After the whole-grain diet, the area under the 2-h insulin curve tended to be lower (-8832 pmol.min/L; 95% CI: -18720, 1062) than after the refined-grain diet. The rate of glucose infusion during the final 30 min of the clamp test was higher after the whole-grain diet (0.07 x 10(-4) mmol.kg(-1).min(-1) per pmol/L; 95% CI: 0.003 x 10(-4), 0.144 x 10(-4))., Conclusion: Insulin sensitivity may be an important mechanism whereby whole-grain foods reduce the risk of type 2 diabetes and heart disease.

Context: Components of the insulin resistance syndrome (IRS), including obesity, glucose intolerance, hypertension, and dyslipidemia, are major risk factors for type 2 diabetes and heart disease. Although diet has been postulated to influence IRS, the independent effects of dairy consumption on development of this syndrome have not been investigated., Objective: To examine associations between dairy intake and incidence of IRS, adjusting for confounding lifestyle and dietary factors., Design: The Coronary Artery Risk Development in Young Adults (CARDIA) study, a population-based prospective study., Setting and Participants: General community sample from 4 US metropolitan areas of 3157 black and white adults aged 18 to 30 years who were followed up from 1985-1986 to 1995-1996., Main Outcome Measure: Ten-year cumulative incidence of IRS and its association with dairy consumption, measured by diet history interview., Results: Dairy consumption was inversely associated with the incidence of all IRS components among individuals who were overweight (body mass index > or =25 kg/m(2)) at baseline but not among leaner individuals (body mass index < 25 kg/m(2)). The adjusted odds of developing IRS (2 or more components) were 72% lower (odds ratio, 0.28; 95% confidence interval, 0.14-0.58) among overweight individuals in the highest (> or =35 times per week, 24/102 individuals) compared with the lowest (<10 times per week, 85/190 individuals) category of dairy consumption. Each daily occasion of dairy consumption was associated with a 21% lower odds of IRS (odds ratio, 0.79; 95% confidence interval, 0.70-0.88). These associations were similar for blacks and whites and for men and women. Other dietary factors, including macronutrients and micronutrients, did not explain the association between dairy intake and IRS., Conclusions: Dietary patterns characterized by increased dairy consumption have a strong inverse association with IRS among overweight adults and may reduce risk of type 2 diabetes and cardiovascular disease.

Dietary fiber may be related to body-weight regulation through plausible physiologic mechanisms that have considerable support in the scientific literature. Many short-term studies suggest that high-fiber foods induce greater satiation and satiety. Epidemiologic studies generally [figure: see text] support a role for fiber in body-weight regulation among free-living individuals consuming self-selected diets, although conclusive intervention studies addressing this point are lacking. Thus, there is considerable reason to conclude that fiber-rich diets, containing non-starchy vegetables, fruits, whole grains, legumes, and nuts, may be effective in the prevention and treatment of obesity in children. Such diets may have additional benefits, independent of changes in adiposity, in the prevention of cardiovascular disease and type 2 diabetes.

Context: Conventional dietary approaches for the treatment of obesity have generally yielded disappointing results., Objective: To examine the effects of a low-glycemic index (GI) diet compared with a standard reduced-fat diet in the management of pediatric obesity., Design: Retrospective cohort study of children attending an outpatient pediatric obesity program from September 1997 to December 1998., Setting: Academic medical center., Participants: One hundred seven obese but otherwise healthy children., Main Outcome Measures: Changes in body mass index (BMI [calculated as weight in kilograms divided by the square of height in meters]) and body weight from first to last clinic visit., Results: A total of 64 patients received the low glycemic index diet and 43 received the reduced-fat diet for 4.3 vs 4.2 months' mean duration of follow-up, with 3.3 vs 3.3 mean number of visits, respectively. Body mass index (-1.53 kg/m(2) [95% confidence interval, -1.94 to -1.12] vs -0.06 kg/m(2) [-0.56 to + 0. 44], P<.001) and body weight (-2.03 kg [95% confidence interval -3. 19 to -0.88] vs +1.31 kg [ -0.11 to + 2.72], P<.001) decreased more in the low-GI group compared with the reduced-fat group. In multivariate models, these differences remained significant (P<.01) after adjustment for age, sex, ethnicity, BMI or baseline weight, participation in behavioral modification sessions, and treatment duration. Significantly more patients in the low-GI group experienced a decrease in BMI of at least 3 kg/m(2) (11 kg/m(2) [17. 2%] vs. 1 kg/m(2) [2.3%], P =.03)., Conclusions: A low-GI diet seems to be a promising alternative to standard dietary treatment for obesity in children. Long-term randomized controlled trials of a low-GI diet in the prevention and treatment of obesity are needed.

It has been suggested that television watching and physical activity are related to obesity. This association, however, has been investigated mainly in children. This study provided the opportunity to examine the relationship between television watching, physical activity, and body mass index in adult Pima Indians, a population with a high prevalence of obesity. Hours per day of television watched, past-year physical levels (MET-h/wk; leisure and occupational combined) and BMI (kg.m-2) were measured in 2452 men and women subjects 21-59 yr old. In adults between the ages of 21 and 39 yr, TV and physical activity levels were negatively correlated (r = -0.11 for men and -0.10 for women). Weaker associations were found between TV and BMI (r = 0.08 for men and 0.04 for women). There were no significant relationships among these variables in older adults (49-59 yr), possibly because of low reported levels of physical activity and TV. Multiple linear regression analysis revealed that physical activity and television watching in men and activity in women were significantly related to BMI. These data suggest that increasing activity levels and decreasing the time spent in sedentary behavior such as watching television should both be considered as potential intervention strategies in obesity prevention programs.