In the UK national grid, electrical energy is transferred through a circuit with a very high potential difference (400,000V) and a very low current. This is said to be because it reduces the heat loss.
However, resistance is "a measure of the difficulty to pass an electric current through that conductor". Surely the resistance would be proportional to the heat loss because resistance and heat loss would both come as a result of an increase in the number of collisions between electrons in the circuit and the wire.
But resistance isn't proportional to heat loss because, in this situation (with a high potential difference and low current), the resistance is very high (due to $V=IR\rightarrow R=\frac{V}{I}$) and the heat loss is very low.
So my question is: what actually affects the resistance and why isn't it proportional to heat loss?