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.
Which brings me to the point of this post. Delta has recently increased the cost of a SkyClub day pass, from $50 to $59. Thatâs almost a 20% increase, which I suppose isnât terrible in and of itself. However, theyâre also decreasing what a lounge pass gets you. It used to be a day pass, meaning you could use it at multiple clubs throughout a day.