3 intervals options; Whats better for fat loss?

[BoredBiker]

Doing HIIT on an eliptical or other machine with programs.

For greater fat loss when using the Interval program, is it more beneficial to;

1. Do faster speed at the high resistance part and slower speed at low resistance.

2. Do slower speed at high resistance and faster speed at low resistance.

3. Or keep my speed the same throughout and let the changing resistance be my only intervals