For a large jet-transport, a useful rule of thumb is that any extra weight carried will result in an extra fuel burn of 4% of that weight per hour.
So, for your example, and extra 200lbs will result in approximately 8lbs per hour of extra fuel burn.
I’m not sure if this rule of thumb applies for such small increments.
It does for large weights: e.g. on the 747-400, carrying an extra 10 tonnes of fuel for a 10 hour flight would result in only 6 tonnes extra remaining at destination.