If you're somebody who can have a tablespoon of peanut butter as part of a snack or meal, and not go back for more, it's probably okay. I have a lot of foods that I do just fine with if I've been eating a very strict ketogenic diet, but that are dangerous to have in the cupboard for a while if I go off plan--like I did at Christmas.

Being tired is also a problem for me, I've had a jar of peanut butter and stuck to an ounce a day for a week or so, and then had one night where I was short on sleep--and ended up in a binge.