Health experts point to sugary beverages as the largest source of added sugar in the American diet, playing a major role in the meteoric rise of childhood obesity over the last 30 years. Our week two challenge to you for Fit Kids February is to make sugary drinks history when it comes to your diet. Our Erin Billups has more on why you should.

Childhood obesity is a complex problem needing a multifaceted approach.

Epidemiologist Dr. Claire Wang, director of the Obesity Prevention Initiative at Columbia University's Mailman School of Public Health, says cutting sugary drinks out of kids' diets can do a lot to reduce the number of overweight children.

"Scientific evidence building over the past few decades have shown us that these beverages - especially when we over-consume these beverages as part of our diet - is detrimental to our health," says Dr. Wang.

She points to the availability of supersized portions and the frequency with which they're consumed as major problems. She says families should consume these beverages - sodas, juices, sports drinks - in moderation.

"That's always my starting point, is how do you make sure your kids know that this special occasion is a treat? It's not an everyday, it's not a staple, it's not a necessity," says Dr. Wang.

The food industry is starting to get the message, offering smaller portion sizes. In addition, some people are cutting back on their sugary drinks.

"There are many initiatives that are taking place in the school grounds to take unhealthy beverages out of the schools and replacing that with something healthier such as water," she says.

But Wang says more needs to be done in so-called food swamps, neighborhoods crammed with fast food outlets and convenience stores with few healthy options. Many of these swamps are in poorer communities, contributing to higher obesity rates among Blacks, Latinos and low-income Americans.

"What is still lacking in terms of the world knowledge is how we can shape the environment better and make the healthy choice the easy choice. So it's not always an uphill battle that we have to struggle, it's something that is natural," Dr. Wang says.