Fuel Cost
The suggestion that 1000kg of extra weight can result in 450 kg extra fuel burn is surely a typo. At airline cruise altitudes and speeds the induced drag (the drag resulting from and directly proportional to the pounds of lift required) is somewhat less than the parasitic drag. A 5% increase in total aircraft weight should therefore result in about 2% increase in fuel consumption to pay for the added load. There is also a very small cost increment to pay for the capital cost of the short term cost of the allegedly excessive investment for fuel.
It costs approximetaly
4% per hour to tanker fuel. Therefore if you are carrying an extra tonne of fuel for 11 hours, it will indeed consume about 44% of its own mass (440kg) simply to carry the extra.