The battle of the bulge has expanded into the toy aisles.

As more American adults dabble in fad diets and the obesity rate among their children swells, toy makers are looking to cash in by designing products meant to encourage physical activity.

But while getting kids off the couch is something toy makers see as a boon for their results, they also know that without the fun aspect, fitness toys will be destined to gather dust in the back of the closet.

Hasbro Inc., Mattel Inc. and JAKKS Pacific Inc. are just a few of the big U.S. toy makers targeting parents concerned about the estimated 16 percent of U.S. children and adolescents who are overweight.

In August, JAKKS unit Play Along launched the Fit n’ Fun Care Bear, who wears a sweatband and does knee bends and other workout moves while singing tunes like the 1980’s Olivia Newton-John hit “Let’s Get Physical.”

Children are encouraged to imitate the Care Bear’s moves, a feature Play Along President Jay Foreman said health-conscious parents will appreciate and that kids will find fun.

“I would love to say we were overly altruistic about the whole thing, but the first and most important thing is whether it’s fun,” Foreman said. “Toys are designed to entertain the child, not necessarily to make them healthier or skinnier.”

Experts agreed that toys like the Fit n’ Fun Care Bear; Hasbro’s BoohBah dolls, based on the toe-touching television characters; and Mattel unit Fisher-Price’s Sesame Street E-L-M-O, who asks kids to join him dancing to “Y-M-C-A,” are more about tapping into a trend than burning calories.

“At the very best these toys model physical activity and inspire kids to be active physically as a mode of entertainment,” said Chris Byrne, an industry expert known as the Toy Guy. “In some cases it’s more on trend from a fashion standpoint, and it doesn’t hurt to be on trend. I’d rather that be the trend than for them to sit back and eat a ham.”

One health expert said toys requiring children to be active in order to play with them are more beneficial than ones that simply encourage movements to be imitated.

“When I think of toys to increase activity in kids, I tend to think more of toys that actually require the kids to be active in order to play with them,” said Jacqueline Epping, a physical activity expert at the U.S. Centers for Disease Control and Prevention.

According to a CDC survey conducted between 1999 and 2002, the number of overweight American children rose 45 percent from the numbers recorded in the period between 1988 and 1994.

Experts blame the rapid increase on several factors, including a decline in required physical education programs in schools and an increased reliance on cars in neighborhoods where children once walked or rode bikes to get around.

“Today there are more choices for children, and a lot of those choices are sedentary,” Epping said, adding that while traditional sports-oriented toys such as roller skates are particularly beneficial to children, video games that require movement are also good for boosting activity levels.

Hasbro’s Lazer Tag, in which players shoot sensors worn by other players to “tag” them, and SpinMaster’s Bella Dancerella, a home ballet kit with a mat, bar and instructional video, also inspire kids to be physically active, Byrne said.

And Japanese publisher Konami Corp. made a hit franchise of “Dance Revolution,” in which players dance frenetically on a special mat attached to their consoles, trying to match the moves of characters on screen. The game even features a “diet mode” that counts the number of calories shed.