Sugar

A vegetarian isn’t tempted by meat. For moral, health, ecological, or spiritual reasons, a person who declares herself a vegetarian has sworn off meat, forever.

You could do the same thing for refined sugar, because if there’s one thing all nutritionists agree on it’s that humans shouldn’t be eating refined sugar in a vast majority of cases. You don’t avoid refined sugar 95% of time time; you avoid it 100% of the time, obviating the need to use your valuable willpower.

There’s a world of difference in the addictive nature of meat and sugar, but still, it might work.