I you and your current bf found yourselves in Survivors in a Pizzahut warehouse filled with enough diet coke and irradiated Pizzas to last a couple a life time then one of you would starve to death and the other would die of dehydration (or more likely one of you would crack, consume a case of diet coke (equivalent of drinking seawater while adrift in an open boat) and set light to the place in a frenzy)
See food quack