How to operate a lower power thermistor power circuit?
Using a load resistor is not only a good idea, it’s simple way to measure the thermistor with an ADC. The thermistor and load resistor form a voltage divider, so you measure the reference feed voltage, then the divider, to derive the thermistor’s resistance.
A way to save power is to only power up the reference feed voltage to the divider when you’re taking the measurement. Then there’s no standby draw.
Also you can use higher-value thermistors, such as 10K ohm. Then the required current is smaller.