The investigators will determine whether people with high muscle mitochondrial capacity produce higher amount of reactive oxygen species (ROS) on consuming high fat /high glycemic diet and thus exhibit elevated cellular oxidative damage. The investigators previously found that Asian Indian immigrants have high mitochondrial capacity in spite of severe insulin resistance. Somalians are another new immigrant population with rapidly increasing prevalence of diabetes. Both of these groups traditionally consume low caloric density diets, and the investigators hypothesize that when these groups are exposed to high-calorie Western diets, they exhibit increased oxidative stress, oxidative damage, and insulin resistance. The investigators will compare Somalians and NE Americans who are matched for age, BMI, and sex. The investigators will measure ROS production in skeletal muscle following high fat/high glycemic diet vs. healthy diet. The investigators will compare the oxidative damage to proteins, DNA, and lipids in these two populations following 10 days of high fat/high glycemic index diet in comparison with low fat diet. The investigators will determine if elevated levels of oxidative damage in Somali immigrant populations is accompanied by high mitochondrial capacity, higher ROS-emitting potential, and lower insulin sensitivity than NE. The proposed study will be performed utilizing the state-of-the-art proteomic and metabolomic methods many of which were recently developed in our laboratory. The investigators expect the results from this study to provide seminal insights into the underlying mechanism of insulin resistance and type 2 diabetes, in addition to demonstrating mechanisms by which a functional proteome is maintained in vivo.

Inclusion Criteria:

• Somali immigrants age 40-65,
• BMI 23-34 kg/m2,
• sedentary (exercise less than 2 days per week for less than 20 minutes).

Inclusion criteria:

• for Northern European descendants same as for Somali immigrants plus need to match a Somali immigrant for age, BMI and habitual activity.

Exclusion Criteria:

• Triglycerides on screening examination of greater than 300;
• pregnant or lactating women.