A menu appears, showing the sugars, carbohydrates and fats contained in their meals. An embedded message in the video is menu board literacy, providing children whose main option may be fast food with the information they need to make healthier choices.
Williams admits that teaching children the importance of cooking meals at home and purchasing healthy groceries would also be effective, but he says that teaching "caloric literacy" can also provide a substantive impact.
For example, he says, cutting 100 calories a day using better menu board literacy could translate to a few thousand calories over a few weeks.
"These small changes are meaningful, and on a population level, these small changes could have very significant impact," he said.
Another video developed for the obesity program teaches children how to achieve their anaerobic threshold, a measure of optimal performance while exercising.
The video, titled "Hip Hop FEET," uses a set of musical beats as a measuring stick for how effectively a child is exercising.
If they breathe before the beats count is up, they are over-exerting themselves. If they don't breathe enough, that means they're not trying hard enough. And if they breathe once at the conclusion of the beats, they've hit their anaerobic threshold.
It is a complex concept simplified for young people.
"It's using hip-hop in a positive way, to have real impact," Doug E. Fresh said. "We use beats that make you really wanna move. You're not just gonna sit there; you wanna get up and do something."
As it turns out, the programs for healthier eating and exercise are doing much more than simply making children move.
Peer-reviewed studies conducted by Williams and colleagues found that immediately after caloric literacy interventions, children changed their food purchases.
"We found that caloric purchases declined by about 25 percent," Williams said. "So they were buying more healthy items as a result of the intervention."
The lingering question for this intervention -- and for the Hip Hop Public Health program more generally -- is how to sustain this change.
After reaching tens of thousands of children in New York, Hip Hop Public Health got a shout-out -- and a request to collaborate -- from the Partnership for a Healthier America, whose ambassador is first lady Michelle Obama.
What evolved from that partnership is an album, to be released Monday, called "Songs for a Healthier America."
The album moves the songs beyond hip-hop into other genres (some of the artists contributing to the album include Ashanti, Travis Barker and Matisyahu) and will be distributed, along with a curriculum, to schools nationwide.
Williams is convinced the model that began in New York, with a neurologist and a few rappers, could make a powerful impact in schools across the country.
"This really teaches us how impressionable kids are and how we have an opportunity to shape their behaviors at a young age," he said.