[skyking]

Originally Posted by maxkang

Most people argue like so, more weight>more lift>more induced drag>more thrust required for cruise flight> more fuel burn, which I think is fair. However, to account for more weight you would fly at a higher speed giving rise to high lift so don't you get to the destination faster? If the optimum range of engine setting allows you to have a higher thrust setting I feel that heavier planes might rather consume less or about the same amount of fuel.

Can you really that simply conclude that heavy planes consume more fuel?

yes you can. It really is that simple. To fly the same speed as a lighter plane, you'd need a higher angle of attack. This takes more thrust. More fuel.
My background is commercial pilot and flight instructor.