No, you can't make overnights oats without chia seeds, or the texture will be runny. In fact, you need high-fiber seeds like chia seeds or flaxseed meal to add a jelly-like texture to the overnight oats. You can use white chia seeds or black chia seeds in this recipe. Other options are to swap the 2 tablespoons of chia seeds with 2 tablespoons of flaxseed meal or 1 tablespoon of whole psyllium husk.