The consumption of low glycemic meals reduces abdominal obesity in subjects with excess body weight.

OBJECTIVE: To evaluate the effect of the glycemic index (GI) on food intake, anthropometric measurements and body composition in subjects with excess body weight. METHODS: Crossover study, in which 17 subjects participated in two study sessions (high GI or low GI). Two daily meals were consumed in laboratory for 30 consecutive days in each session. Subjects also consumed under free living conditions 3 daily isocaloric servings of fruits, presenting the same GI as the session in which they were participating. At each 15 days, subjects were submitted to body composition (lean mass and fatty mass) and anthropometric indexes (weight, height, body mass index, waist circumference (WC), hip circumference, hip-waist relation (WHC)) assessment. Habitual food intake was assessed before and at the end of each session. Subjects were instructed to maintain the same level of physical activity during the study. RESULTS: There was a significant reduction on WC and WHC after the low GI session. The other parameters did not differ between the treatments applied in this study. CONCLUSION: These results suggest that the consumption of low GI foods may favor the prevention and control abdominal obesity and the associated metabolic diseases.

The influence of endotoxemia on the molecular mechanisms of insulin resistance.

INTRODUCTION: The reduction in the capacity of insulin to reach its biological effects can lead to a chronic hyperglycemia and hyperinsulinemia, assuming an important role in the pathogenesis of metabolic disorders associated to obesity and diabetes. Insulin resistance is associated to chronic subclinical inflammation, which in part can be mediated by increased plasmatic lipopolysaccharide levels, an endotoxin derived from the membrane of gramnegative bacteria that mainly reside in the gut. OBJECTIVES: The aim of this review study is to describe the molecular mechanisms involved in the pathogenesis of insulin resistance due to metabolic endotoxemia and of its connection to obesity and diabetes. RESULTS AND DISCUSSION: Lipopolysaccharide present in the intestinal lumen can reach the circulatory system causing metabolic endotoxemia. When lipopolysaccharide binds to Toll-like receptor 4, inflammation is activated, changing several stages of insulin signaling. It has been shown that chronic exposure to this endotoxin may contribute to weight gain and type 2 diabetes mellitus manifestation. Obese and diabetic people have increased plasmatic lipopolysaccharide levels. The increase in the number of gram-negative bacteria on gut microbiota, the reduction on gut mucosal integrity, and the consumption of high-fat diets increase the plasmatic lipopolysaccharide levels. Therefore, the type of diet consumed may modulate the composition of gut microbiota and improve gut mucosal integrity, decreasing the occurrence of endotoxemia and its postprandial inflammatory effects, leading to adequate insulin signaling. However, there are very few studies that evaluated the influence of nutrients and/or specific food types on metabolic endotoxemia.

Influence of the glycemic index and glycemic load of the diet in the glycemic control of diabetic children and teenagers.

OBJECTIVE: Evaluate the influence of the glycemic index (GI) and glycemic load (GL) of the diet in the glycemic control of children and teenagers with type 1 diabetes mellitus (DM1). METHODS: A total of 146 subjects, aged 7-19 years, monitored at the Division of Pediatric Endocrinology at the HC/UFMG participated in the study. The consumed diet was evaluated using a quantitative food frequency questionnaire previously validated and tested in a pilotproject. The GI of the participant's diet was estimated according to the equation described by Wolever and Jenkins (1986). The GL was estimated using the equation proposed by Foster-Powell et al. (2002). The glycemic control was classified as good, intermediate or poor according to the average of two HbA1c values obtained six months prior to the dietary evaluation date. RESULTS: Subjects that had good glycemic control consumed diets with significantly (Tukey test, p = 0.000) lower GI/GL (54.8 ± 2.7/118.3 ± 29.8) than the ones with intermediate (60.1 ± 3.8/142.5 ± 27.3) and poor (60.3 ± 4.1/153.7 ± 40.7) glycemic control. The diet consumed by 75.5% of diabetics with good glycemic control was classified as medium GL, suggesting that the consumption of medium GL diet may favor an adequate glycemic control. The low GI diet consumed by these participants also presented higher protein content, which might have contributed to the attenuation of the postprandial glycemic response and better glycemic control of these patients. CONCLUSION: The intake of a reduced GI/GL diet favors the glycemic control of the studied population.

The role of hyperglycemia in the induction of oxidative stress and inflammatory process.

INTRODUCTION: In many countries, the prevalence of obesity and chronic diseases has been increased, which are normally associated with changes in lifestyle, that are especially characterized by high consumption of diets rich in carbohydrates of rapid absorption. Such diets classified as high glycemic index and high glycemic load can lead to hyperglycemia. OBJECTIVES: Discuss the role of the diets of high glycemic index and/or high glycemic load on the oxidative stress and inflammatory process, in order to verify their influence on those diseases. RESULTS AND DISCUSSION: Studies demonstrate direct relationship between hyperglycemia, inflammatory process and oxidative stress that contribute to the development of chronic diseases.

Gut microbiota and the development of obesity.

INTRODUCTION: Advances in tools for molecular investigations have allowed deeper understanding of how microbes can influence host physiology. A very interesting field of research that has gained attention recently is the possible role of gut microbiota in the development of obesity and metabolic disorders. OBJECTIVE: The aim of this review is to discuss mechanisms that explain the influence of gut microbiota on host metabolism. RESULTS AND DISCUSSION: The gut microbiota is important for normal physiology of the host. However, differences in their composition may have different impacts on host metabolism. It has been shown that obese and lean subjects present different microbiota composition profile. These differences in microbiota composition may contribute to weight imbalance and impaired metabolism. The evidences from animal models suggest that it is possible that the microbiota of obese subjects has higher capacity to harvest energy from the diet providing substrates that can activate lipogenic pathways. In addition, microorganisms can also influence the activity of lipoprotein lipase interfering in the accumulation of triglycerides in the adipose tissue. The interaction of gut microbiota with the endocannabinoid system provides a route through which intestinal permeability can be altered. Increased intestinal permeability allows the entrance of endotoxins to the circulation, which are related to the induction of inflammation and insulin resistance in mice. The impact of the proposed mechanisms for humans still needs further investigations. However, the fact that gut microbiota can be modulated through dietary components highlights the importance to study how fatty acids, carbohydrates, micronutrients, prebiotics, and probiotics can influence gut microbiota composition and the management of obesity. Gut microbiota seems to be an important and promising target in the prevention and treatment of obesity and its related metabolic disturbances in future studies and in clinical practice.

Effect of the glycemic index on lipid oxidation and body composition.

Several studies have been conducted to evaluate the effects of the consumption of the slowly absorbed carbohydrates in a low glycemic index (GI) diet on fat oxidation, in order to obtain dietetic treatment that can favor the achievement of an adequate body composition. Therefore, the purpose of this study was to analyze studies in which the role of low GI diets on body composition, with emphasis on fat oxidation. An internet search for articles, in English or Portuguese, published since 1995, was conducted using the following key words: glycemic index, glycemic load, glycaemic index, glycaemic load, body fat, body composition, fat oxidation. Papers that described animals or humans clinical trials were selected. Data were collected from Web of Science, Science Direct, Pubmed. It was verified that the results of the majority of the analyzed studies indicated that low GI diets lead to a lower insulin response, increasing body fat oxidation. These results indicate that the consumption of low GI diet can be an important strategy to be used for the prevention and control of obesity and chronic diseases associated to it.