In my airline it would use extra fuel Since i,am certain
that the weights used are mostly incorrect.
76kg as an average for male/female in our case.
All our planes are 4 to 5% highconsumers, and after looking into all the variables it looks like paxweights estimates too low are the cause for this.
Using actual weight would of course not increase the actual burn ,but would increase the flightplan fuel since the basis then is a higher ZFW to start with.