[Kaira]

Mr. Runcible lost weight fairly quick when I put him on a diet.
Well, it was more that I stated to give him the right amount of
food and not a diet at all. That and some walks was all that it
took and he was perfect again after some weeks. Now, I've
changed his food so I've had to adjust the amount once again,
because he started to gain weight.

And as someone here stated above, dog wil generally still want
more food after being fed the proper amount.