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.
Fees are never fun. Here are the annual fees that come with these cards: 1  Delta Gold â $0 introductory annual fee for the first year, then $95. 2  Delta Platinum â $195 (this is NOT waived the first year).