If you're saying "hallelujah" that your beloved coffee is on this list, then you're in luck; you don't even need to enjoy it black on the keto diet. While you can't add sugar, Catherine recommends a splash of half-and-half, heavy cream, or an unsweetened milk alternative, such as almond milk, coconut milk, or pea protein milk. Skim milk, 2 percent, and full-fat milk have too much sugar in the form of lactose to be keto-friendly. If you need a little bit of sweetness, try stevia.