Pet sitting, the ultimate weight loss strategy

Who would have thought that the best trainer I could possibly have is a dog.
Though not just any dog seeing as I have a miniature poodle who is good for nothing but being terrified of a leaf, keeping your feet warm as a travel size hot water bottle (that follows you around non the less), and hogging the bed.
No, the dog I am referring to is Ozzie, the Australian Shepard. He is about 5 or so years old, a beautiful brown and white color, an enormous pink tongue, and energy to rival a pack of 8 year old boys.
While his family is out on vacation until tonight, I've been taking care of said dog and a cat (who is too lofty to listen to what I say even when I bribe her with treats and toys). Part of the arrangement was to take Ozzie to the dog park every day.
Ozzie LOVES the dog park, and I can't say that I mind it all that much especially with the regionally unusual nice weather. Between skipping breakfast to let him out in the morning, spending half my lunch throwing the ball to Ozzie in the back yard, and then running around after him at the dog park, I have no time to eat!
See Ozzie is probably one of the smartest dogs i know. You take him for a walk, and he'll want you to throw the ball to the exclusion even of sniffing other dog's butts. JUST THROW THE BALL! Once you throw the ball, he'll sort of run back to you and drop it on the path in front of where you're walking. He'll do his business, possibly pay a dog or two a little mind, but by the time you walk up to where he dropped the ball....he's waiting for you to throw it again.
However, when i tried to steer him back to the car, Ozzie tried a new ploy. Instead of putting the ball down in front of me...he runs by me and drops it behind me away from the car. When that ploy didn't work because, i needed to pick up the girls soon, he decided to run away and hide from me in some very tall grass. Every time i got him into my sight...he would look at me like "see, isn't this more fun?" Then take off again.
I finally got him back on the leash and dropped off last night.
I checked my weight this morning; since starting to pet sit Ozzie....I've lost 6 lbs in 5 days...............*begrudgingly thanks Ozzie with a treat*