ABC News' Abbie Boudreau reports:

Everyone knows how much fun dinner can be with kids who are fed up.

But one mom who is a nutritionist says that what people have always thought about feeding their kids is wrong. She says to let them eat what they want and never say to your child, "Clean your plate."

Maryann Jacobsen, a mother of two and a registered dietician based in San Diego, believes that forcing kids to finish their food can lead to obesity later in life.

"I think it's an outdated practice and it's really not useful in teaching kids how to listen to their body," Jacobsen told ABC News. "We're sending out kids into the world when they become adults to clean their plates of a restaurant meal with 1,200 calories. So it really doesn't make sense."

A 2007 study found that 85 percent of parents try to get young children to eat more at mealtime and, according to other research published in Pediatrics in May, most parents ask adolescents to clear their plate.

So Jacobsen serves "family style" meals, allowing her 4- and 6-year-old children to decide what to eat, and how much. She thinks kids know when they've had enough.

"A parent's job is to provide the food, the structure and when it occurs," Jacobsen said. "But it's the kids' job to decide how much and whether to eat."

In a book she co-authored, "Fearless Feeding," Jacobsen explains that cleaning one's plate could lead to picky eating, weight problems and eating disorders.

But Toronto parenting expert Karyn Gordon disagrees, insisting that her 6-year-old twins are too young to announce their menu.

"A lot of children will say, 'I'm full,' when, in reality, they don't like the food," Gordon said.

ABC News senior medical contributor Dr. Jennifer Ashton says that although portion control is a factor, "It's really not about quantity, it's about quality."