Tomato paste is a keto-friendly ingredient as long as you're careful about the brand you're using (some include added sugars). Choose a tomato paste that has zero grams of added sugar. I've made this keto meatloaf with regular tomato paste and Cento double concentrated tomato paste (in a tube) and both work well using the same amount. It's such a small amount and when divided into each portion, the carb and sugar count remains very low.