Preheat your oven to 350°F (175°C). Grease a 12-cup muffin tin or line with paper liners.
In a large bowl, whisk together the whole wheat flour, all-purpose flour, rolled oats, poppy seeds, baking powder, baking soda, and salt.
In another bowl, mix the Greek yogurt, honey, lemon juice, lemon zest, eggs, and melted coconut oil until well combined.
Pour the wet ingredients into the dry ingredients and stir until just combined. Do not overmix.
Divide the batter evenly among the prepared muffin cups.
Bake for 18-20 minutes, or until a toothpick inserted into the center of a muffin comes out clean.
Allow the muffins to cool in the tin for 5 minutes, then transfer to a wire rack to cool completely.