In diesel engines the power generated is directly controlled by the amount of fuel delivered - if you want more power, inject more fuel. Unlike most spark ignit

In diesel engines the power generated is directly controlled by the amount of fuel delivered - if you want more power, inject more fuel. Unlike most spark ignition engines, there is no throttle valve, you control the stroke of the diesel pump (or the time the injectors stay open in common rail engines). So it is completely wrong to say that they use more fuel at 50% load than at 80%.