Why? Well, because glycolysis is a very exergonic process. So remember in our discussion of glycolysis, we said that when 1 mol of glucose is broken down inside our body under physiological conditions, that releases about 96.2 kilojoules per mole of energy. And so the breakdown of glycolysis as it is an extremely exercise process, it takes place spontaneously and irreversibly. So what that means is if gluconeogenesis was simply the reverse of this process, then every time 1 mol of Pyruvate is transformed into 1 mol of glucose, that would require an input of 96.2 kilojoules of energy. And so what that means is gluconeogenesis would be a very, very inefficient and expensive process.