Effect of Isocaloric Ultra Processed Versus Unprocessed Diets on Insulin Sensitivity

Nutrition science is beginning to place less emphasis on the nutrient composition of the diet and more emphasis on its comprising foods. A particular public health concern involves the consumption of foods that result from extensive industrial processing. Ultra-processed foods have become increasingly common and now contribute the majority of calories consumed in America. The rise in the prevalence of obesity, type 2 diabetes, and metabolic syndrome over the past several decades is believed to have been caused, in part, by the parallel increase in production, advertising, and consumption of ultra-processed foods. However, the metabolic effects of industrial processing per se, independent of diet calories or macronutrient composition, have not been carefully investigated in a controlled feeding study. Therefore, we will conduct an inpatient controlled feeding study in 20 overweight and obese adult men to investigate the changes in multi-organ insulin sensitivity and hepatic triglyceride content resulting from consuming two test diets for a pair of 3 week periods. The test diets will be implemented in a randomized, crossover design with each test diet following a 1 week run-in period of inpatient controlled feeding of a standard metabolic diet. The test diets will be matched for calories, macronutrient composition, sugar, fiber, and sodium, but one diet will be composed of ultra-processed foods whereas the other diet will be unprocessed foods. Multi-organ insulin sensitivity and hepatic triglyceride content will be measured at the end of each 1 week run-in period as well as at the end of each 3 week test diet period.