X-Message-Number: 12030
Date: Tue, 29 Jun 1999 17:46:04 -0700 (PDT)
From: Doug Skrecky <>
Subject: glycemic index and obesity

  LEF has proposed that decreases inconjugated linoleic acid intake are
responsible for the high incidence of obesity in the USA. Here's an
alternative explanation. -Doug

  Ludwig DS.  Majzoub JA.  Al-Zahrani A.  Dallal GE.  Blanco I.  Roberts SB.
  Division of Endocrinology, Department of Medicine, Children's
  Hospital,Boston, 300 Longwood Ave, Boston, MA 02115, USA.
  High glycemic index
  foods, overeating, and obesity.
  Pediatrics.  103(3):E26, 1999 Mar.
  OBJECTIVE: The prevalence of obesity has increased dramatically in recent
  years. However, the role of dietary composition in body weight regulation
  remains unclear. The purpose of this work was to investigate the acute
  effects of dietary glycemic index (GI) on
  energy metabolism and voluntary food intake in obese subjects. METHODS:
  Twelve obese teenage boys were evaluated on three separate occasions using a
  crossover study protocol. During each evaluation, subjects consumed identical
  test meals at breakfast and lunch that had a low, medium, or
  high GI. The high- and medium-GI meals were
  designed to have similar macronutrient composition, fiber content, and
  palatability, and all meals for each subject had equal energy content. After
  breakfast, plasma and serum concentrations of metabolic fuels and hormones
  were measured. Ad libitum food intake was determined in the 5-hour period
  after lunch. RESULTS: Voluntary energy intake after the
  high-GI meal (5.8 megajoule [mJ]) was 53% greater than after
  the medium-GI meal (3.8 mJ), and 81% greater than after the low-GI meal (3.2
  mJ). In addition, compared with the low-GI meal, the high-GI
  meal resulted in higher serum insulin levels, lower plasma
  glucagon levels, lower postabsorptive plasma glucose and serum fatty acids
  levels, and elevation in plasma epinephrine. The area under the
  glycemic response curve for each test meal accounted for 53%
  of the variance in food intake within subjects. CONCLUSIONS: The rapid
  absorption of glucose after consumption of high-GI meals
  induces a sequence of hormonal and metabolic changes that promote excessive
  food intake in obese subjects. Additional studies are needed to examine the
  relationship between dietary GI and long-term body weight regulation.

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