How do defense levels work...?

I'm training range at the abyss with a blood fury with full armadyl and level 81 defense, but I'm still needing food to top up my health. I did mage training here from 83 to 99 and didn't need to eat once, but obvs I have less protection against the relevant combat style they use now.

I thought about training my defence to 90 first, and using extreme defense potions to boost it further in order to sustain my health whilst ranging, along with a blood fury?

This might be a stupid question, but does anyone know how effective this would be? I'm sure it would help, but by how much? Would I greatly reduce the likely of taking damage, or the amount of damage I take, or both? Should this be the first priority over getting soul split? Would take me about 6 hours to get the defense levels and I can already make extreme defense potions. SS would take me a lot longer to get..

Anyone have experience training range at the abyss with just a blood fury to sustain life points?

SUMMARY: how much do defense stats alone help in reducing damage taken...?