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.
More construction ahead as Delta relocates at LAX. Delta Air Lines invested $229 million to overhaul Los Angeles International Airport's Terminal 5, but now the Atlanta-based carrier is moving to terminals 2 and 3 at the airport. (Getty Images)