Why does fast phase 1 detox mean I should be more careful with grilled meat?

Grilled meat can contain potentially toxic substance (HCA/PAH). Neutralising these toxic substances, and the first step in the process can create intermediate compounds that are actually more toxic, before phase 2 neutralises these into safe products.

If you rapidly create these intermediates through fast phase 1 detoxification, you will accumulate a higher concentration of toxic intermediates more rapidly, meaning they are more likely to have toxic effects.

If you're a slow metaboliser, you get a much slower accumulation of the toxins, and so the body can deal with them more effectively.