Stir the warm water, honey and yeast together in a small bowl. Let it sit for 7-10 minutes until foamy on top. The yeast consumes the honey, so it does not add carbs to the finished bread.
In the bowl of a stand mixer, whisk together the vital wheat gluten, flaxseed meal, oat fiber, erythritol, salt and xanthan gum.
Lightly beat the eggs, then add them to the dry ingredients along with the softened butter and the foamy yeast mixture.
Knead with the dough hook on medium speed for 7-8 minutes, until the dough is smooth, stretchy and pulls away from the sides of the bowl.
Shape the dough into a log and place it in a greased 8.5x4.5-inch loaf pan. Cover with a clean towel and let it rise in a warm spot for 60-75 minutes, until nearly doubled in size.
Preheat the oven to 350°F. Bake the loaf for 30-35 minutes, until deep golden brown and it sounds hollow when tapped on top.
Brush the hot loaf with melted butter. Cool in the pan for 10 minutes, then transfer to a wire rack and cool completely before slicing.