MC34063A power consumption calculation
It may be easier to think if it in terms of power. The input power will be the output power divided by the efficiency (say70%) plus the power of the controlling circuitry.
So for 8V @ 200mA the output power is 1600mW. At an efficiency of 70% (not very good but you may not get much better for this circuitry) this is 2280mW. Add the power for the controller (3.7*2.5 = ~10) to get 2290mW.
Divide by the input voltage to get the input current 2290/3.7 = ~620mA. This is subject to a fair amount of variation depending upon the exact circuit used.