Instruct: Given a question, retrieve documents that answer the question.
Query: The Spillover Effect Links Obesity to Diabetes
Human adiposity has long been associated with insulin resistance and increased cardiovascular risk, and abdominal adiposity is considered particularly adverse. Intra-abdominal fat is associated with insulin resistance, possibly mediated by greater lipolytic activity, lower adiponectin levels, resistance to leptin, and increased inflammatory cytokines, although the latter contribution is less clear. Liver lipid is also closely associated with, and likely to be an important contributor to, insulin resistance, but it may also be in part the consequence of the lipogenic pathway of insulin action being up-regulated by hyperinsulinemia and unimpaired signaling. Again, intramyocellular triglyceride is associated with muscle insulin resistance, but anomalies include higher intramyocellular triglyceride in insulin-sensitive athletes and women (vs men). Such issues could be explained if the "culprits" were active lipid moieties such as diacylglycerol and ceramide species, dependent more on lipid metabolism and partitioning than triglyceride amount. Subcutaneous fat, especially gluteofemoral, appears metabolically protective, illustrated by insulin resistance and dyslipidemia in patients with lipodystrophy. However, some studies suggest that deep sc abdominal fat may have adverse properties. Pericardial and perivascular fat relate to atheromatous disease, but not clearly to insulin resistance. There has been recent interest in recognizable brown adipose tissue in adult humans and its possible augmentation by a hormone, irisin, from exercising muscle. Brown adipose tissue is metabolically active, oxidizes fatty acids, and generates heat but, because of its small and variable quantities, its metabolic importance in humans under usual living conditions is still unclear. Further understanding of specific roles of different lipid depots may help new approaches to control obesity and its metabolic sequelae.
BACKGROUND: In 2010, overweight and obesity were estimated to cause 3·4 million deaths, 3·9% of years of life lost, and 3·8% of disability-adjusted life-years (DALYs) worldwide. The rise in obesity has led to widespread calls for regular monitoring of changes in overweight and obesity prevalence in all populations. Comparable, up-to-date information about levels and trends is essential to quantify population health effects and to prompt decision makers to prioritise action. We estimate the global, regional, and national prevalence of overweight and obesity in children and adults during 1980-2013. METHODS: We systematically identified surveys, reports, and published studies (n=1769) that included data for height and weight, both through physical measurements and self-reports. We used mixed effects linear regression to correct for bias in self-reports. We obtained data for prevalence of obesity and overweight by age, sex, country, and year (n=19,244) with a spatiotemporal Gaussian process regression model to estimate prevalence with 95% uncertainty intervals (UIs). FINDINGS: Worldwide, the proportion of adults with a body-mass index (BMI) of 25 kg/m(2) or greater increased between 1980 and 2013 from 28·8% (95% UI 28·4-29·3) to 36·9% (36·3-37·4) in men, and from 29·8% (29·3-30·2) to 38·0% (37·5-38·5) in women. Prevalence has increased substantially in children and adolescents in developed countries; 23·8% (22·9-24·7) of boys and 22·6% (21·7-23·6) of girls were overweight or obese in 2013. The prevalence of overweight and obesity has also increased in children and adolescents in developing countries, from 8·1% (7·7-8·6) to 12·9% (12·3-13·5) in 2013 for boys and from 8·4% (8·1-8·8) to 13·4% (13·0-13·9) in girls. In adults, estimated prevalence of obesity exceeded 50% in men in Tonga and in women in Kuwait, Kiribati, Federated States of Micronesia, Libya, Qatar, Tonga, and Samoa. Since 2006, the increase in adult obesity in developed countries has slowed down. INTERPRETATION: Because of the established health risks and substantial increases in prevalence, obesity has become a major global health challenge. Not only is obesity increasing, but no national success stories have been reported in the past 33 years. Urgent global action and leadership is needed to help countries to more effectively intervene. FUNDING: Bill & Melinda Gates Foundation. Copyright © 2014 Elsevier Ltd. All rights reserved.
Obesity remains a major public health challenge, and its prevalence is dramatically increasing. Diet and exercise are typically recommended to prevent and manage obesity; however, the results are often conflicting. Polyphenols, a class of phytochemicals that have been shown to reduce the risk factors for diabetes type II and cardiovascular diseases, are recently suggested as complementary agents in the management of obesity through several mechanisms such as decreasing fat absorption and/or fat synthesis. Dark chocolate, a high source of polyphenols, and flavanols in particular, has lately received attention for its possible role in modulating obesity because of its potential effect on fat and carbohydrate metabolism, as well as on satiety. This outcome was investigated in animal models of obesity, cell cultures and few human observational and clinical studies. The research undertaken to date has shown promising results, with the possible implication of cocoa/dark chocolate in the modulation of obesity and body weight through several mechanisms including decreasing the expression of genes involved in fatty acid synthesis, reducing the digestion and absorption of fats and carbohydrates and increasing satiety. Copyright © 2013 John Wiley & Sons, Ltd.
BACKGROUND: Previous studies have examined individual dietary and lifestyle factors in relation to type 2 diabetes, but the combined effects of these factors are largely unknown. METHODS: We followed 84,941 female nurses from 1980 to 1996; these women were free of diagnosed cardiovascular disease, diabetes, and cancer at base line. Information about their diet and lifestyle was updated periodically. A low-risk group was defined according to a combination of five variables: a bodymass index (the weight in kilograms divided by the square of the height in meters) of less than 25; a diet high in cereal fiber and polyunsaturated fat and low in trans fat and glycemic load (which reflects the effect of diet on the blood glucose level); engagement in moderate-to-vigorous physical activity for at least half an hour per day; no current smoking; and the consumption of an average of at least half a drink of an alcoholic beverage per day. RESULTS: During 16 years of follow-up, we documented 3300 new cases of type 2 diabetes. Overweight or obesity was the single most important predictor of diabetes. Lack of exercise, a poor diet, current smoking, and abstinence from alcohol use were all associated with a significantly increased risk of diabetes, even after adjustment for the body-mass index. As compared with the rest of the cohort, women in the low-risk group (3.4 percent of the women) had a relative risk of diabetes of 0.09 (95 percent confidence interval, 0.05 to 0.17). A total of 91 percent of the cases of diabetes in this cohort (95 percent confidence interval, 83 to 95) could be attributed to habits and forms of behavior that did not conform to the low-risk pattern. CONCLUSIONS: Our findings support the hypothesis that the vast majority of cases of type 2 diabetes could be prevented by the adoption of a healthier lifestyle.
Background Some persistent environmental chemicals are suspected of causing an increased risk of type 2 diabetes mellitus, a disease particularly common after age 70. This concern was examined in a cross-sectional study of elderly subjects in a population with elevated contaminant exposures from seafood species high in the food chain. Methods Clinical examinations of 713 Faroese residents aged 70-74 years (64% of eligible population) included fasting plasma concentrations of glucose and insulin, and glycosylated hemoglobin. Lifetime exposure to persistent environmental chemicals from pilot whale and other traditional food was estimated from a dietary questionnaire and by analysis of blood samples for polychlorinated biphenyls (PCBs) and related food contaminants. Results Septuagenarians with type 2 diabetes or impaired fasting glycemia tended to have higher PCB concentrations and higher past intake of traditional foods, especially during childhood and adolescence. In non-diabetic subjects, the fasting insulin concentration decreased by 7% (95% CI= −12% to −2%) for each doubling of the PCB concentration after adjustment for sex and body mass index at age 20. Conversely, the fasting glucose concentration increased by 6% (−1% to 13%) for each doubling in PCB. Similar associations were seen in subjects without impaired fasting glycemia, while further adjustment for current body mass index and lipid metabolism parameters attenuated some of the associations. Conclusions Impaired insulin secretion appears to constitute an important part of the type 2 diabetes pathogenesis associated with exposure to persistent lipophilic food contaminants.
OBJECTIVE Ad36, a human adenovirus, increases adiposity but improves glycemic control in animal models. Similarly, natural Ad36 infection is cross-sectionally associated with greater adiposity and better glycemic control in humans. This study compared longitudinal observations in indices of adiposity (BMI and body fat percentage) and glycemic control (fasting glucose and insulin) in Ad36-infected versus uninfected adults. RESEARCH DESIGN AND METHODS Baseline sera from Hispanic men and women (n = 1,400) were screened post hoc for the presence of Ad36-specific antibodies. Indices of adiposity and glycemic control at baseline and at ∼10 years past the baseline were compared between seropositive and seronegative subjects, with adjustment for age and sex. In addition to age and sex, indices of glycemic control were adjusted for baseline BMI and were analyzed only for nondiabetic subjects. RESULTS Seropositive subjects (14.5%) had greater adiposity at baseline, compared with seronegative subjects. Longitudinally, seropositive subjects showed greater adiposity indices but lower fasting insulin levels. Subgroup analyses revealed that Ad36-seropositivity was associated with better baseline glycemic control and lower fasting insulin levels over time in the normal-weight group (BMI ≤25 kg/m2) and longitudinally, with greater adiposity in the overweight (BMI 25–30 kg/m2) and obese (BMI >30 kg/m2) men. Statistically, the differences between seropositive and seronegative individuals were modest in light of the multiple tests performed. CONCLUSIONS This study strengthens the plausibility that in humans, Ad36 increases adiposity and attenuates deterioration of glycemic control. Panoptically, the study raises the possibility that certain infections may modulate obesity or diabetes risk. A comprehensive understanding of these under-recognized factors is needed to effectively combat such metabolic disorders.
The purpose of this study was to examine the relationship of body mass index, abdomen-hip ratio, and dietary intake to fasting and postprandial insulin concentrations among 652 men aged 43-85 y, followed in the Normative Aging Study. Log-transformed fasting insulin was significantly associated with body mass index, abdomen-hip ratio, total fat energy, and saturated fatty acid energy, with correlation coefficients ranging from 0.14 for total fat to 0.45 for body mass index. When multivariate models were used, body mass index, abdomen-hip ratio, and saturated fatty acid intake were statistically significant independent predictors of both fasting and postprandial insulin concentrations, after age, cigarette smoking, and physical activity were adjusted for. If saturated fatty acids as a percentage of total energy were to decrease from 14% to 8%, there would be an 18% decrease in fasting insulin and a 25% decrease in postprandial insulin. These data suggest that overall adiposity, abdominal obesity, and a diet high in saturated fatty acids are independent predictors for both fasting and postprandial insulin concentrations.
OBJECTIVE: To quantify per capita and aggregate medical expenditures and the value of lost productivity, including absenteeism and presenteeism, because of overweight, and grade I, II, and III obesity among U.S. employees. METHODS: Cross-sectional analysis of the 2006 Medical Expenditure Panel Survey and the 2008 National Health and Wellness Survey. RESULTS: Among men, estimates range from -$322 for overweight to $6087 for grade III obese men. For women, estimates range from $797 for overweight to $6694 for grade III. In aggregate, the annual cost attributable to obesity among full-time employees is $73.1 billion. Individuals with a body mass index >35 represent 37% of the obese population but are responsible for 61% of excess costs. CONCLUSIONS: Successful efforts to reduce the prevalence of obesity, especially among those with a body mass index >35, could result in significant savings to employers.
CONTEXT: Dietary composition may affect insulin secretion, and high insulin levels, in turn, may increase the risk for cardiovascular disease (CVD). OBJECTIVE: To examine the role of fiber consumption and its association with insulin levels, weight gain, and other CVD risk factors compared with other major dietary components. DESIGN AND SETTING: The Coronary Artery Risk Development in Young Adults (CARDIA) Study, a multicenter population-based cohort study of the change in CVD risk factors over 10 years (1985-1986 to 1995-1996) in Birmingham, Ala; Chicago, III; Minneapolis, Minn; and Oakland, Calif. PARTICIPANTS: A total of 2909 healthy black and white adults, 18 to 30 years of age at enrollment. MAIN OUTCOME MEASURES: Body weight, insulin levels, and other CVD risk factors at year 10, adjusted for baseline values. RESULTS: After adjustment for potential confounding factors, dietary fiber showed linear associations from lowest to highest quintiles of intake with the following: body weight (whites: 174.8-166.7 lb [78.3-75.0 kg], P<.001; blacks: 185.6-177.6 lb [83.5-79.9 kg], P = .001), waist-to-hip ratio (whites: 0.813-0.801, P = .004; blacks: 0.809-0.799, P = .05), fasting insulin adjusted for body mass index (whites: 77.8-72.2 pmol/L [11.2-10.4 microU/mL], P = .007; blacks: 92.4-82.6 pmol/L [13.3-11.9 microU/mL], P = .01) and 2-hour postglucose insulin adjusted for body mass index (whites: 261.1-234.7 pmol/L [37.6-33.8 microU/mL], P = .03; blacks: 370.2-259.7 pmol/L [53.3-37.4 microU/mL], P<.001). Fiber was also associated with blood pressure and levels of triglyceride, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and fibrinogen; these associations were substantially attenuated by adjustment for fasting insulin level. In comparison with fiber, intake of fat, carbohydrate, and protein had inconsistent or weak associations with all CVD risk factors. CONCLUSIONS: Fiber consumption predicted insulin levels, weight gain, and other CVD risk factors more strongly than did total or saturated fat consumption. High-fiber diets may protect against obesity and CVD by lowering insulin levels.
The study hypothesis was that fasting glucose, insulin, fructosamine, C-reactive protein, and interleukin-6 decrease and adiponectin increases with daily flaxseed consumption in overweight or obese individuals with pre-diabetes. In this randomized, cross-over study overweight or obese men and postmenopausal women (n = 25) with pre-diabetes consumed 0, 13, or 26 g ground flaxseed for 12 weeks. Glucose, insulin, homeostatic model assessment (HOMA-IR), and normalized percent of α-linolenic fatty acid (ALA) were significantly different by treatment (multiple analysis of variance, P = .036, P = .013, P = .008, P = .024 respectively). Paired t tests showed glucose decreased on the 13 g intervention compared to the 0 g period [13 g = -2.10 ± 1.66 mg/L (mean ± SEM), 0 g = 9.22 ± 4.44 mg/L, P = .036]. Insulin decreased on the 13 g intervention but not the 26 g (P = .021) and 0 g (P = .013) periods (13 g = -2.12 ± 1.00 mU/L, 26 g = 0.67 ± 0.84 mU/L, 0 g = 1.20 ± 1.16 mU/L). HOMA-IR decreased on the 13 g period but not on the 26 g (P = .012) and 0 g (P = .008) periods (13 g = -0.71 ± 0.31, 26 g = 0.27 ± 0.24, 0 g = 0.51 ± 0.35). The α-linolenic fatty acid decrease for the 0 g period was different than the 13 g (P = .024) and 26 g (P = .000) periods (13 g = 0.20 ± 0.04, 26 g = 0.35 ± 0.07, 0 g = -0.01 ± 0.07). Fructosamine, high sensitivity C-reactive protein, adiponectin, and high-sensitivity interleukin-6 had no significant differences. Flaxseed intake decreased glucose and insulin and improved insulin sensitivity as part of a habitual diet in overweight or obese individuals with pre-diabetes. Copyright © 2013 Elsevier Inc. All rights reserved.
BACKGROUND: Epidemiologic studies have shown inverse associations between nut consumption and diabetes, cardiovascular disease (CVD), and all-cause mortality, but results have not been consistent. OBJECTIVE: We assessed the relation between nut intake and incidence of type 2 diabetes, CVD, and all-cause mortality. DESIGN: We searched PubMed and EMBASE for all prospective cohort studies published up to March 2013 with RRs and 95% CIs for outcomes of interest. A random-effects model was used to pool risk estimates across studies. RESULTS: In 31 reports from 18 prospective studies, there were 12,655 type 2 diabetes, 8862 CVD, 6623 ischemic heart disease (IHD), 6487 stroke, and 48,818 mortality cases. The RR for each incremental serving per day of nut intake was 0.80 (95% CI: 0.69, 0.94) for type 2 diabetes without adjustment for body mass index; with adjustment, the association was attenuated [RR: 1.03; 95% CI: 0.91, 1.16; NS]. In the multivariable-adjusted model, pooled RRs (95% CIs) for each serving per day of nut consumption were 0.72 (0.64, 0.81) for IHD, 0.71 (0.59, 0.85) for CVD, and 0.83 (0.76, 0.91) for all-cause mortality. Pooled RRs (95% CIs) for the comparison of extreme quantiles of nut intake were 1.00 (0.84, 1.19; NS) for type 2 diabetes, 0.66 (0.55, 0.78) for IHD, 0.70 (0.60, 0.81) for CVD, 0.91 (0.81, 1.02; NS) for stroke, and 0.85 (0.79, 0.91) for all-cause mortality. CONCLUSIONS: Our meta-analysis indicates that nut intake is inversely associated with IHD, overall CVD, and all-cause mortality but not significantly associated with diabetes and stroke. The inverse association between the consumption of nuts and diabetes was attenuated after adjustment for body mass index. These findings support recommendations to include nuts as part of a healthy dietary pattern for the prevention of chronic diseases. © 2014 American Society for Nutrition.
Background One of the outcomes positively associated with dioxin exposure in humans is type 2 diabetes. Objectives This study was conducted in order to find the molecular biological evidence for the diabetogenic action of dioxin in adipose samples from Vietnam veterans. Methods We obtained 313 adipose tissue samples both from Vietnam veterans who were exposed to dioxin (Operation Ranch Hand) and from comparison veterans who served in Southeast Asia with no record of dioxin exposure. We conducted quantitative reverse-transcribed polymerase chain reaction studies on selected marker mRNAs from these samples. Results We found the most sensitive and reliable molecular indicator of dioxin-induced diabetes to be the ratio of mRNA of glucose transporter 4 (GLUT4) and nuclear transcription factor kappa B (NFκB), a marker of inflammation. This ratio showed significant correlations to serum dioxin residues and to fasting glucose among those in the Ranch Hand group and, surprisingly, even in the comparison group, who have low levels of dioxin comparable to the general public. Such a correlation in the comparison group was particularly significant among those with known risk factors such as obesity and family history of diabetes. Conclusions These results show that the GLUT4:NFκB ratio is a reliable marker for the diabetogenic action of dioxin, particularly at very low exposure levels that are not much higher than those found in the general public, implying a need to address current exposure levels.
Obesity and type 2 diabetes have been associated with a high-fat diet (HFD) and reduced mitochondrial mass and function. We hypothesized a HFD may affect expression of genes involved in mitochondrial function and biogenesis. To test this hypothesis, we fed 10 insulin-sensitive males an isoenergetic HFD for 3 days with muscle biopsies before and after intervention. Oligonucleotide microarray analysis revealed 297 genes were differentially regulated by the HFD (Bonferonni adjusted P < 0.001). Six genes involved in oxidative phosphorylation (OXPHOS) decreased. Four were members of mitochondrial complex I: NDUFB3, NDUFB5, NDUFS1, and NDUFV1; one was SDHB in complex II and a mitochondrial carrier protein SLC25A12. Peroxisome proliferator-activated receptor gamma coactivator-1 (PGC1) alpha and PGC1beta mRNA were decreased by -20%, P < 0.01, and -25%, P < 0.01, respectively. In a separate experiment, we fed C57Bl/6J mice a HFD for 3 weeks and found that the same OXPHOS and PGC1 mRNAs were downregulated by approximately 90%, cytochrome C and PGC1alpha protein by approximately 40%. Combined, these results suggest a mechanism whereby HFD downregulates genes necessary for OXPHOS and mitochondrial biogenesis. These changes mimic those observed in diabetes and insulin resistance and, if sustained, may result in mitochondrial dysfunction in the prediabetic/insulin-resistant state.
Background Obesity and physical inactivity are associated with several chronic conditions, increased medical care costs, and premature death. Methods We used the Behavioral Risk Factor Surveillance System (BRFSS), a state-based random-digit telephone survey that covers the majority of United States counties, and the National Health and Nutrition Examination Survey (NHANES), a nationally representative sample of the US civilian noninstitutionalized population. About 3.7 million adults aged 20 years or older participated in the BRFSS from 2000 to 2011, and 30,000 adults aged 20 or older participated in NHANES from 1999 to 2010. We calculated body mass index (BMI) from self-reported weight and height in the BRFSS and adjusted for self-reporting bias using NHANES. We calculated self-reported physical activity—both any physical activity and physical activity meeting recommended levels—from self-reported data in the BRFSS. We used validated small area estimation methods to generate estimates of obesity and physical activity prevalence for each county annually for 2001 to 2011. Results Our results showed an increase in the prevalence of sufficient physical activity from 2001 to 2009. Levels were generally higher in men than in women, but increases were greater in women than men. Counties in Kentucky, Florida, Georgia, and California reported the largest gains. This increase in level of activity was matched by an increase in obesity in almost all counties during the same time period. There was a low correlation between level of physical activity and obesity in US counties. From 2001 to 2009, controlling for changes in poverty, unemployment, number of doctors per 100,000 population, percent rural, and baseline levels of obesity, for every 1 percentage point increase in physical activity prevalence, obesity prevalence was 0.11 percentage points lower. Conclusions Our study showed that increased physical activity alone has a small impact on obesity prevalence at the county level in the US. Indeed, the rise in physical activity levels will have a positive independent impact on the health of Americans as it will reduce the burden of cardiovascular diseases and diabetes. Other changes such as reduction in caloric intake are likely needed to curb the obesity epidemic and its burden.
Until recently, the majority of cases of diabetes mellitus among children and adolescents were immune-mediated type 1a diabetes. Obesity has led to a dramatic increase in the incidence of type 2 diabetes (T2DM) among children and adolescents over the past 2 decades. Obesity is strongly associated with insulin resistance, which, when coupled with relative insulin deficiency, leads to the development of overt T2DM. Children and adolescents with T2DM may experience the microvascular and macrovascular complications of this disease at younger ages than individuals who develop diabetes in adulthood, including atherosclerotic cardiovascular disease, stroke, myocardial infarction, and sudden death; renal insufficiency and chronic renal failure; limb-threatening neuropathy and vasculopathy; and retinopathy leading to blindness. Health care professionals are advised to perform the appropriate screening in children at risk for T2DM, diagnose the condition as early as possible, and provide rigorous management of the disease.
There is increasing evidence that obesity in humans is associated with infection with human adenovirus-36 (Adv36). Infection of experimental animals with Adv36 demonstrates that this virus causes obesity. Human studies have shown a prevalence of Adv36 infection of 30% or greater in obese adult humans, but a correlation with obesity has not always been demonstrated. In contrast, three published studies and one presented study with a total of 559 children all show that there is an increase in prevalence of Adv36 infection in obese children (28%) compared to non-obese children (10%). The explanation for the apparently more robust correlation of Adv36 infection with obesity in children vs. adults is not clear. The data in animals and people suggests that Adv36 has contributed to the worldwide increase in childhood obesity. More research is needed to identify prevalences and consequences of Adv36 infection in people of all age groups and geographic locations.
If disease patterns emerge which show that certain diseases can be related, this is a valuable pointer to a common cause. This article traces the principle of interpreting disease relationships, illustrated by several common conditions of western civilization, for which the common cause is postulated as being removal of fiber from the diet.
The metabolic abnormalities of type 2 diabetes can be reversed reproducibly by bariatric surgery. By quantifying the major pathophysiological abnormalities in insulin secretion and insulin action after surgery, the sequence of events leading to restoration of normal metabolism can be defined. Liver fat levels fall within days and normal hepatic insulin sensitivity is restored. Simultaneously, plasma glucose levels return towards normal. Insulin sensitivity of muscle remains abnormal, at least over the weeks and months after bariatric surgery. The effect of the surgery is explicable solely in terms of energy restriction. By combining this information with prospective observation of the changes immediately preceding the onset of type 2 diabetes, a clear picture emerges. Insulin resistance in muscle, caused by inherited and environmental factors, facilitates the development of fatty liver during positive energy balance. Once established, the increased insulin secretion required to maintain plasma glucose levels will further increase liver fat deposition. Fatty liver causes resistance to insulin suppression of hepatic glucose output as well as raised plasma triacylglycerol. Exposure of beta cells to increased levels of fatty acids, derived from circulating and locally deposited triacylglycerol, suppresses glucose-mediated insulin secretion. This is reversible initially, but eventually becomes permanent. The essential time sequence of the pathogenesis of type 2 diabetes is now evident. Muscle insulin resistance determines the rate at which fatty liver progresses, and ectopic fat deposition in liver and islet underlies the related dynamic defects of hepatic insulin resistance and beta cell dysfunction. These defects are capable of dramatic reversal under hypoenergetic feeding conditions, completely in early diabetes and to a worthwhile extent in more established disease.
This study reviewed the literature on the relations between exposure to chemicals with endocrine-disrupting abilities and obesity in humans. The studies generally indicated that exposure to some of the endocrine-disrupting chemicals was associated with an increase in body size in humans. The results depended on the type of chemical, exposure level, timing of exposure and gender. Nearly all the studies investigating dichlorodiphenyldichloroethylene (DDE) found that exposure was associated with an increase in body size, whereas the results of the studies investigating polychlorinated biphenyl (PCB) exposure were depending on dose, timing and gender. Hexachlorobenzene, polybrominated biphenyls, beta-hexachlorocyclohexane, oxychlordane and phthalates were likewise generally associated with an increase in body size. Studies investigating polychlorinated dibenzodioxins and polychlorinated dibenzofurans found either associations with weight gain or an increase in waist circumference, or no association. The one study investigating relations with bisphenol A found no association. Studies investigating prenatal exposure indicated that exposure in utero may cause permanent physiological changes predisposing to later weight gain. The study findings suggest that some endocrine disruptors may play a role for the development of the obesity epidemic, in addition to the more commonly perceived putative contributors. © 2011 The Authors. obesity reviews © 2011 International Association for the Study of Obesity.
Obesity is associated with a great diversity of diseases including non-alcoholic fatty liver disease. Our recent report suggested that oat, rich in beta-glucan, had a metabolic-regulating and liver-protecting effect in an animal model. In this study, we performed a clinical trial to further confirm the effect of oat. Subjects with BMI ≥27 and aged 18-65, were randomly divided into a control (n=18) and an oat-treated (n=16) group, taking a placebo or beta glucan-containing oat cereal, respectively, for 12 weeks. Our data showed that consumption of oat reduced body weight, BMI, body fat and the waist-to-hip ratio. Profiles of hepatic function, including AST, but especially ALT, were useful resources to help in the evaluation of the liver, since both showed decrements in patients with oat consumption. Nevertheless, anatomic changes were still not observed by ultrasonic image analysis. Ingestion of oat was well tolerated and there was no adverse effect during the trial. In conclusion, consumption of oat reduced obesity, abdominal fat, and improved lipid profiles and liver functions. Taken as a daily supplement, oat could act as an adjuvant therapy for metabolic disorders.
The ongoing epidemics of obesity is one main health concern of the present time. Overeating in some obese individuals shares similarities with the loss of control and compulsive behavior observed in drug-addicted subjects, suggesting that obesity may involve food addiction. Here, we review the contributions provided by the use of positron emission tomography to the current understanding of the cerebral control of obesity and food intake in humans. The available studies have shown that multiple areas in the brain are involved with the reward properties of food, such as prefrontal, orbitofrontal, somatosensory cortices, insula, thalamus, hypothalamus, amygdala, and others. This review summarizes the current evidence, supporting the concepts that i) regions involved in the somatosensory response to food sight, taste, and smell are activated by palatable foods and may be hyperresponsive in obese individuals, ii) areas controlling executive drive seem to overreact to the anticipation of pleasure during cue exposure, and iii) those involved in cognitive control and inhibitory behavior may be resistant to the perception of reward after food exposure in obese subjects. All of these features may stimulate, for different reasons, ingestion of highly palatable and energy-rich foods. Though these same regions are similarly involved in drug abusers and game-addicted individuals, any direct resemblance may be an oversimplification, especially as the heterogeneities between studies and the prevalent exclusion of sensitive groups still limit a coherent interpretation of the findings. Further work is required to comprehensively tackle the multifaceted phenotype of obesity and identify the role of food dependency in its pathophysiology. Copyright © 2012 S. Karger GmbH, Freiburg.
Obesity is associated with a great diversity of diseases including non-alcoholic fatty liver disease. Our previous report suggested that Hibiscus sabdariffa extracts (HSE) had a metabolic-regulating and liver-protecting potential. In this study, we performed a clinical trial to further confirm the effect of HSE. Subjects with a BMI ≧ 27 and aged 18-65, were randomly divided into control (n = 17) and HSE-treated (n = 19) groups, respectively, for 12 weeks. Our data showed that consumption of HSE reduced body weight, BMI, body fat and the waist-to-hip ratio. Serum free fatty acid (FFA) was lowered by HSE. Anatomic changes revealed that HSE improved the illness of liver steatosis. Ingestion of HSE was well tolerated and there was no adverse effect during the trial. No alteration was found for serum α-amylase and lipase. The clinical effect should mainly be attributed to the polyphenols of HSE, since composition analysis showed that branched chain-amino acids, which is associated with obesity, is not obviously high. In conclusion, consumption of HSE reduced obesity, abdominal fat, serum FFA and improved liver steatosis. HSE could act as an adjuvant for preventing obesity and non-alcoholic fatty liver.
Background Type 2 diabetes affects approximately 8 percent of adults in the United States. Some risk factors — elevated plasma glucose concentrations in the fasting state and after an oral glucose load, over-weight, and a sedentary lifestyle — are potentially reversible. We hypothesized that modifying these factors with a lifestyle-intervention program or the administration of metformin would prevent or delay the development of diabetes. Methods We randomly assigned 3234 nondiabetic persons with elevated fasting and post-load plasma glucose concentrations to placebo, metformin (850 mg twice daily), or a lifestyle-modification program with the goals of at least a 7 percent weight loss and at least 150 minutes of physical activity per week. The mean age of the participants was 51 years, and the mean body-mass index (the weight in kilograms divided by the square of the height in meters) was 34.0; 68 percent were women, and 45 percent were members of minority groups. Results The average follow-up was 2.8 years. The incidence of diabetes was 11.0, 7.8, and 4.8 cases per 100 person-years in the placebo, metformin, and lifestyle groups, respectively. The lifestyle intervention reduced the incidence by 58 percent (95 percent confidence interval, 48 to 66 percent) and metformin by 31 percent (95 percent confidence interval, 17 to 43 percent), as compared with placebo; the lifestyle intervention was significantly more effective than metformin. To prevent one case of diabetes during a period of three years, 6.9 persons would have to participate in the lifestyle-intervention program, and 13.9 would have to receive metformin. Conclusions Lifestyle changes and treatment with metformin both reduced the incidence of diabetes in persons at high risk. The lifestyle intervention was more effective than metformin.
The intake of added sugars, such as from table sugar (sucrose) and high-fructose corn syrup has increased dramatically in the last hundred years and correlates closely with the rise in obesity, metabolic syndrome, and diabetes. Fructose is a major component of added sugars and is distinct from other sugars in its ability to cause intracellular ATP depletion, nucleotide turnover, and the generation of uric acid. In this article, we revisit the hypothesis that it is this unique aspect of fructose metabolism that accounts for why fructose intake increases the risk for metabolic syndrome. Recent studies show that fructose-induced uric acid generation causes mitochondrial oxidative stress that stimulates fat accumulation independent of excessive caloric intake. These studies challenge the long-standing dogma that “a calorie is just a calorie” and suggest that the metabolic effects of food may matter as much as its energy content. The discovery that fructose-mediated generation of uric acid may have a causal role in diabetes and obesity provides new insights into pathogenesis and therapies for this important disease.
OBJECTIVE: To evaluate whether plasma levels of free fatty acids (FFAs) are independently associated with incidence of type 2 diabetes. RESEARCH DESIGN AND METHODS: A case-cohort design was used to randomly select 580 incident cases of diabetes and 566 noncases from 10,275 African-American and white men and women in the Atherosclerosis Risk in Communities study, aged 45-64 years and without prevalent diabetes at the baseline exam. Incident diabetes was ascertained at three exams over 9 years of follow-up. FFA levels were measured in plasma samples collected at the baseline exam. RESULTS: At baseline, FFA level was inversely associated with height and positively associated with female sex, BMI, waist circumference, waist-to-hip ratio, heart rate, plasma triglycerides, and an inflammation score quantifying levels of six systemic inflammation markers. Relative risks for incident diabetes (fourth vs. first quartile of FFAs) were increased in a basic model adjusted for age, sex, race, and center (hazard ratio 1.68, 95% CI 1.20-2.34) and in a model further adjusted for baseline fasting glucose, insulin, BMI, waist circumference, triglycerides, and the inflammation score (1.63, 1.04-2.57). Relative risks associated with a greater FFA level were lowest among those of normal weight and highest among the obese, but a formal test of interaction between FFAs and BMI was not statistically significant. CONCLUSIONS: Individuals with higher fasting levels of plasma FFAs were at modestly higher risk of type 2 diabetes in this cohort of middle-aged adults.