Physiological validation of the concept of glycemic load in lean young adults.

Human Nutrition Unit, School of Molecular and Microbial Biosciences, University of Sydney, Sydney, NSW, Australia.
Journal of Nutrition (Impact Factor: 4.23). 09/2003; 133(9):2728-32.
Source: PubMed

ABSTRACT Dietary glycemic load, the mathematical product of the glycemic index (GI) of a food and its carbohydrate content, has been proposed as an indicator of the glucose response and insulin demand induced by a serving of food. To validate this concept in vivo, we tested the hypotheses that 1). portions of different foods with the same glycemic load produce similar glycemic responses; and 2). stepwise increases in glycemic load for a range of foods produce proportional increases in glycemia and insulinemia. In the first study, 10 healthy subjects consumed 10 different foods in random order in amounts calculated to have the same glycemic load as one slice of white bread. Capillary blood samples were taken at regular intervals over the next 2 h. The glycemic response as determined by area under the curve was not different from that of white bread for nine foods. However, lentils produced lower than predicted responses (P < 0.05). In the second study, another group of subjects was tested to determine the effects of increasing glycemic load using a balanced 5 x 5 Greco-Latin square design balanced for four variables: subject, dose, food and order. Two sets of five foods were consumed at five different glycemic loads (doses) equivalent to one, two, three, four and six slices of bread. Stepwise increases in glycemic load produced significant and predictable increases in both glycemia (P < 0.001) and insulinemia (P < 0.001). These findings support the concept of dietary glycemic load as a measure of overall glycemic response and insulin demand.

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    ABSTRACT: During the incremental test, after reaching the anaerobic threshold, the lactate concentration increases exponentially. Additionally, the blood glycemia changes with the intensity and duration of the exercise. The present study aimed to verify the lactate and glycemic responses to a maximal incremental non-incline treadmill test. For that, 17 individuals, volunteers, were submitted to an incremental treadmill test, with an initial speed of 5 km/h and 1 km/h increments every minute, with no inclination. Before the tests, the volunteers consumed a breakfast meal containing 60.61% carbohydrate, 12.91% protein and 26.48% lipids. For the analysis of the blood lactate, were collected two blood samples: at rest and from 3 to 5 minutes after the test. For the analysis of the blood glycemia, were collected three blood samples: fasting, at rest 15 minutes after the provided meal, and from 3 to 5 minutes after the test. The Shapiro Wilk test was used to verify the normality of the data. For the lactate analysis, was applied the student's t-test. For the glycemia analysis, was applied the ANOVA for repeated measures, with post hoc Bonferroni. The level of significance of the study was p < 0.05. The results indicated a significant increase in the lactate after the exercise (p = 0.002). The glycemia increased significantly after the exercise in relation to the fast (p = 0.015) and the rest (p = 0.042). Therefore, the maximal incremental in a non-incline treadmill test was capable of increasing significantly the lactate concentration and the blood glycemia.
    International Journal of Sports Science & Coaching 03/2015; 2015(5(2)):59-64. DOI:10.5923/j.sports.20150502.03 · 0.93 Impact Factor
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    ABSTRACT: Objective To determine if consumption of a reduced-carbohydrate (CHO) diet would result in preferential loss of adipose tissue under eucaloric conditions, and whether changes in adiposity were associated with changes in postprandial insulin concentration. Methods In a crossover-diet intervention, 30 women with PCOS consumed a reduced-CHO diet (41:19:40%energy from CHO:protein:fat) for 8 weeks and a standard diet (55:18:27) for 8 weeks. Body composition by DXA and fat distribution by CT were assessed at baseline and following each diet phase. Insulin AUC was obtained from a solid meal test (SMT) during each diet phase. Results Participants lost 3.7% and 2.2% total fat following the reduced-CHO diet and STD diet, resp. (p< 0.05 for difference between diets). The reduced-CHO diet induced a decrease in subcutaneous-abdominal, intra-abdominal, and thigh-intermuscular adipose tissue (-7.1%, -4.6%, and -11.5%, resp.), and the STD diet induced a decrease in total lean mass. Loss of fat mass following the reduced CHO diet arm was associated with lower insulin AUC (p< 0.05) during the SMT. Conclusions In women with PCOS, consumption of a diet lower in CHO resulted in preferential loss of fat mass from metabolically harmful adipose depots, whereas a diet high in CHO appeared to promote repartitioning of lean mass to fat mass.
    Metabolism 07/2014; 63(10). DOI:10.1016/j.metabol.2014.07.007 · 3.61 Impact Factor

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