If the tsh is elevated and the free T4 is low this is considered hypothyroidism, a 5.3 is really normal
in some labs and a little elevated
in some. I would consider repeating the level and including a tsh and free T4 to compare. Then discuss all the other important reasons she may have had rapid weight gain. Is she drinking juice-if so stop it completely and have her eat her fruit instead, this includes juice boxes.