Why was this study done?

Determining which components of food lower the glycemic response is important for both good blood sugar control and weight loss. This study was designed to determine which macronutrient (fat or protein) has the most effect on lowering blood sugar response to a carbohydrate meal.

What did the study find?

This study suggested that protein and not fat had the biggest effect on maintaining a lower blood sugar.

Effect on Postprandial glycemia of a Formula Diet and its Carbohydrate Fraction with or Without Protein and Fat
Authors: Spiller GA, et al. Am J Clin Nutr, 1984. 39(4):671.
PDF Abstract: Am J Clin Nutr, 1984.