Gretchen Rubin taught me that I am an abstainer. When I see a box of cookies, I have a binary choice of eating either no cookies, or bingeing on the entire box. In contrast, moderators can have a few cookies and walk away from the rest. I know this is also true of alcohol and drugs, not just sweets. I am an abstainer (all or nothing), not a moderator. Knowing this has helped me to have the power to walk away from temptations (sometimes), knowing that if I have one, I will have all.
Abel James did a podcast about this topic in an interview with Gretchen Rubin. I recommend listening to the podcast, or at least reading the transcript.