A substance, both a hormone and neurotransmitter, secreted by the adrenal medulla and the nerve endings of the sympathetic nervous system to cause vasoconstriction and increases in heart rate, blood pressure, and the sugar level of the blood. Also called levarterenol, noradrenalin. norepinephrine.
Foods that only contain protein, fat or both -- and are carb-free -- are few and far between. Most foods contain at least some carbohydrates. However, plant-based oils, other pure fats -- like butter and margarine -- meats, poultry, seafood and eggs are the best sources of carb-free foods.
Fish lacks carbs and provides omega-3 fatty acids. You have a lot of zero-carb foods to choose from on a low-carb diet. All of the major proteins -- meat, poultry and fish -- are naturally free of carbs and sugar. A variety of oils, vinegars and seasonings are also on the carb-free list. But there are some exceptions.