The fatty acids trans-C16:1 and cis-C16:1 have been associated with healthy plasma glucose levels. Elevated glucose levels have been associated with diabetes. This study is designed to determine whether there is a dose-response relation between how much trans-C16:1 and cis-C16:1 you consume and how much appears in plasma. This information will be used to design a future study to determine whether trans-C16:1 and cis-C16:1 could be used to treat diabetes. Trans-C16:1 occurs naturally in dairy fat such as milk and cheese, while cis-C16:1 occurs naturally in nuts, particularly, macadamia nuts, and a plant called sea buckthorn. The study will consist of two 9-week phases, with a minimum of a 4 week off-study period between the two phases. Fasting blood will be drawn at baseline (first day of week 1), 3 weeks, 6 weeks and 9 weeks (4 total blood draws per phase or 8 total blood draws for 2 phases). During each phase you will be asked to consume increasing numbers of vegetable oil capsules, 2 per day during the first 3 weeks, 4 per day during the second 3 weeks, and 8 per day during the third 3 weeks. During each of these periods you should take half the capsules in the morning and half in the evening, with your meals. You will be randomly assigned to receive the trans-C16:1 or cis-C16:1 during the first phase and the other during the second phase. The total length of the study is about 18 weeks, not including the break between phase 1 and phase 2 (not less than 4 weeks). The trans-C16:1 in the capsules will be in the form of partially-hydrogenated soybean oil. The cis-C16:1 in the other capsules will be in the form of sea buckthorn oil.