Mookie is a 2' 6", 24 lb. wolverine from ZooMontana who constantly watches her weight. Mookie can't eat just anything; she is on a strict diet. Her keeper, Krystal Wetham, helps her stay lean and mean, "by not just feeding her strips of meat that have big old chunks of fat on it for starters."

That's just the beginning; Wetham makes her exercise everyday by hiding treats and scattering scents throughout Mookie's habitat. "This will give her more of a barrier to get the food. It's not just something sitting in front of her. It's not easy, she has to work for it and she has to think about it," Wetham says.

This is important. These perky pals need to pump up the volume.

"That exhibit can never really change a whole lot so we have to change some of the aspects in it for them get them to run around and keep them active," says Jackie Worstell, Zoo Director.

Some of the animals take more work than others. The otters like to cheat.

Worstell says, "Because they have an open exhibit, at times they're able to get their own food. Every now and then they've had a duck that's landed in their pond and fell victim to them."

But all in all, the animals are weighed regularly and their food is portioned accordingly to keep them fit and trim and make sure none of the animals at ZooMontana are over or underweight.

Zoo Nutritionists first started to appear in the 1970's and '80's, and now about 20 of the 216 accredited zoos and aquariums have full-time nutritionists.