Their probably not eating all that honey. Their rearranging it to set up the broodnest. In the spring mine want two deeps for the brood. At the end of winter it's not uncommon to have all the brood in the bottom and nothing but capped honey in the top. As soon as buildup starts they'll move some down leaving a honey band circling the top of all the frames they plan on using for brood.
By mid/late summer the top deep will be back filled with honey and the brood in the bottom.
By mid/late summer the top deep will be back filled with honey and the brood in the bottom.