alisoncc
I am afraid you have been poorly advised about fuel consumption (but you are not the first).
Let us take it one step at a time:
The Harrier has a jet engine.
The amount of fuel you can burn in a jet engine depends on the amount of air going though it.
In the hover or during a VTO the engine is sucking in air.
When you are flying fast the air is rammed in.
If you want to see some high fuel flows then get going fast - you will be surprised especially at low level on a cold day.
With your new found knowledge you will now realise why the Harrier uses less fuel from VTO until it reaches its cruising speed on the first leg heading than it does using a conventional takeoff (and one of those silly runways that are never pointing in the direction you want to go)
JF