I know on the paleo diet peanuts are not recommended because they are a legume, however, I have seen several recipes calling for peanut flour and/or peanut butter (obviously the all-natural kind not the sugar-laden Jiffy kind) in keto cookbooks.
Peanuts are okay in moderation (7g net carbs per 100g) but pecans and brazils are even better (4g per 100g) or macadamia nuts (5g per 100g). I’ve never used peanut flour so am unable to comment about that, but there’s no reason why you can’t use sugar free peanut butter and just make sure you count the carbs accordingly. Enjoy! 🙂
I’d also add a caution regarding peanuts – just like nuts (even though they’re not a nut), peanuts can be easy to overeat (and they do contain carbs like type1ketogirl points out). And that can make it tough to lose weight.
They also contain a high amount of phytic acid which can prevent you from absorbing minerals in your food.
Something else to watch out for in peanuts is aflatoxin (linked to cancer) and peanut agglutinin (linked to digestive issues).
I’d suggesting going for nuts like macadamias or nut flours like almond flour.