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 is a key partner in the $6 billion infrastructure modernization project at the worldâs busiest hub and this boarding process will continue to rollout at Delta gates across HartsfieldâJackson International Airport as part of a $400 million terminal and concourse renovation.