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.
Delta Air Lines Delta charges an award ticket redeposit fee of $150, which is waived for Diamond and Platinum Medallion members. Award tickets not canceled at least 72 hours prior to the originating flight departure time are nonrefundable; however, Delta representatives have been known to grant exceptions.