Effects of Dietary Macronutrient Intake on Insulin Sensitivity and Secretion and Glucose and Lipid Metabolism in Healthy, Obese Adolescents

Journal of Clinical Endocrinology and Metabolism. 2005;90(8):4496-502.

In previous studies, the investigator has shown that non-obese adolescents have tremendous capacity to adjust to a wide range of carbohydrate and fat intake by exclusively altering carbohydrate oxidation and insulin sensitivity without altering insulin secretion. Furthermore, fructose fed at a low level (10 percent of the diet carbohydrate fraction) or high level (40 percent of the carbohydrate fraction) did not have any impact on insulin secretion, insulin sensitivity or glucose effectiveness. The current study will determine if this adaptability is maintained in obese adolescents. Another possible outcome is that a high carbohydrate diet and/or high fructose intake will increase insulin secretion but not insulin sensitivity, thereby increasing risk for developing type II diabetes.

Findings

• Obese, healthy adolescents insulin resistant on HC & LC and maintained normal fasting glucose on HC by increasing insulin secretion
• Nonobese adolescents adapt to high CHO intakes by exclusively increasing CHO oxidation and insulin sensitivity without altering insulin secretion; fructose content did not impact this
• Effects of obesity outweighs those of dietary macronutrient composition except: the obese teens on a high carbohydrate diet needed to increase insulin secretion further to maintain normal blood glucose.
• Increasing gluconeogenesis in obese teens on low carbohydrate (high fat) may indicate hepatic insulin resistance

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