1 Leptin is a powerful and influential hormone produced by your fat cells. 2  It plays a key role in regulating energy intake and energy expenditure.
(Upgrades are not available on fares in the L, T, and U range, however, which are the most deeply discounted.) To calculate the price of an upgrade, Delta charges a dollar amount per 500 miles. $50: Up to 500 miles. $75: 501-1000 miles. $100: 1001-1500 miles.
Visit delta.com/medallion for more information. Medallion Complimentary Upgrades for Award Tickets and Pay with Miles reservations will be upgraded beginning at the eligible Medallion tier window based on availability and are not eligible for Medallion Complimentary Companion Upgrades.