As we have said, when bears (including cubs) are in hyperphagia they eat almost nonstop, around the clock. As a result, they get chubbier and chubbier, or chonkier, if you prefer.
Hyperphagia alters the routines of the cubs, as they spend more and more of their time eating. They need lots of water, too, so they drink a lot. (The sapling murdalizing is not a part of the hyperphagia routine.)