One can of Great Northern Beans has 35 net carbs, which translates to a little over 0.5 g net carbs per buckeye. This is well within THM:S guidelines.
Troubleshooting:
-If your natural peanut butter is pretty "dry", you probably won't need the full amount of oat fiber. For best results, make sure all the oil is stirred into the jar of peanut butter so it's smooth and oily. If your peanut butter is on the dry side, you may wish to add a couple extra tablespoons of coconut oil to the buckeyes.
-Use refined coconut oil, such as Louana brand, so you don't have a coconut flavor in these buckeyes.
-I would not suggest substituting anything for the oat fiber. You may be able to substitute another low-carb flour such as almond flour or coconut flour, but I'm not sure how that would taste (and it would definitely be more calorie-dense than the oat fiber). Oat fiber absorbs a lot of liquid, so take that into consideration. I know some people use protein powder as a substitute for oat fiber in recipes, but I haven't tried that and have my doubts that a cup of protein powder would taste good in this recipe (not to mention that it would be pretty expensive.).