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.
Upgrade Notification. â 1 Wâ Class will be a valid class used for Delta Comfort+ as a fare and when a customer is upgraded into Delta Comfort+. 2  Medallion members will be notified of their new Delta Comfort+ seat assignment via email and will have the option to change to another Delta Comfort+ seat, if available.