This episode made me slightly afraid of losing weight, I'll be honest. Oh, and both Kirby and the Pillsbury Dough Boy.
Donna returns, looking for the Doctor. So she's on the trail of a fishy pill that makes the weight "fall off." Literally. Turns out, the Doctor is too, and they end up joining together.
I should pause to explain something. I watched this episode about two weeks ago (that's my guess anyway), and at the time I just really did not like Donna, so I'll say I don't like Donna when writing about these episodes, but I eventually got over that and started to like her, though I almost hate myself for it. I always hate when I hate someone then end up liking them. I feel like such a hypocrite. Anyways, in this episode, and the next few I didn't like Donna. I felt she was annoying, and just complained about the Doctor and everything he did, and was far, far too sentimental and touchy-feely for my tastes. But she got better. She stopped complaining about everything, and threatening to go home. I think it was after episode 4 that I started to like her and enjoy her and the Doctor's relationship and little stuff. It's fun now. So yes. That was that episode. She decided to go with the Doctor, obviously. And she's the new companion.