Glycemic and insulinemic responses to energy bars of differing macronutrient composition in healthy adults

This study investigated how energy bars of differing macronutrient composition affect postprandial glycemia and insulinemia in normal subjects compared with white bread and chicken breast controls.

A total of 20 healthy adult subjects were recruited to participate in this randomized block protocol. After an overnight fast, subjects were fed 60-g portions of one of 5 meals, which were as follows: low carbohydrate bar (Atkins Advantage Bar, LC), moderate carbohydrate bar (Balance Bar, MC), high carbohydrate bar (Power Bar, HC), white bread (WB), and chicken breast (CHI). Capillary fingerstick and venous blood samples were analyzed for glucose and insulin concentrations, respectively, at baseline and at 15, 30, 45, 60, 90 and 120 minutes after start of the test meal.

Compared with WB, plasma glucose area under the curve (AUC) for the meals was: 71% (P<0.001) lower for the LC bar, 50% (P<0.001) lower for MC bar, 4% (P=0.996) higher for the HC bar, and 83% (P<0.001) lower for the CHI. Serum insulin AUC, again compared with WB, was: 26% (P=0.497) lower for the LC bar, 35% (P=0.210) higher for the MC bar, 73% (P<0.001) higher for the HC bar, and 78% (P<0.001) lower for the CHI.

This study demonstrated that substitution of other macronutrients for carbohydrate is effective for reducing postprandial glycemia. However, the insulin response may not decrease to the same degree and, for some bars, may actually be elevated compared with white bread.