Weight Loss Diet Study: Low Carb vs Low Fat

The investigators hope to learn whether matching the weight loss diet to one's insulin resistance status will increase weight loss the success. The relevance of these findings is highlighted by the fact that the national recommendations for weight loss are to follow a high-carbohydrate, low-fat diet. This would imply that about half the population has been given the wrong advice in regards to the most successful dietary pattern for weight loss. Plasma fatty acid composition patterns have been shown to be associated with both insulin resistance and/or carbohydrate intake. As secondary analyses, the investigators will explore: (1) differences in plasma fatty acid composition between insulin sensitive and resistant participants at baseline; (2) the correlations between insulin markers and plasma fatty acid composition at baseline; (3) the interaction between insulin status and diet on 6-month changes in the plasma fatty acid composition; (4) plasma fatty acid composition changes in participants on low fat and low carbohydrate diets after 6 months; and (5) the correlations between changes in insulin markers, dietary components, and plasma fatty acid composition after 6 months.