And the answer to America's obesity epidemic is: We all need to watch more of Charlie Rose.
It has long been established that television watching is linked to unhealthy eating. A 2011 meta-study, which examined the results of 53 previously published papers, concluded that television can "act as a distraction, resulting in a lack of awareness of actual food consumption, or overlooking food cues that may lead to overconsumption."
OK, but do certain kinds of programs act as more effective distractions, leading to higher levels of mindless eating? That's the issue addressed in the new study, conducted by a research team led by Aner Tal of Cornell University.
A 2011 meta-study, which examined the results of 53 previously published papers, concluded that television can "act as a distraction, resulting in a lack of awareness of actual food consumption, or overlooking food cues that may lead to overconsumption."
Ninety-four undergraduates gathered in groups of up to 20 to watch TV for 20 minutes. Each participant was provided with "generous amounts of four snacks—M&Ms, cookies, carrots, and grapes—and allowed to eat as much as they wanted." The food was weighed before and after the sessions to determine how much of each item was eaten.
The students were randomly assigned to watch one of three programs: An excerpt from the action movie The Island, starring Ewan McGregor and Scarlett Johansson; a segment of the PBS interview program hosted by Charlie Rose; or that same excerpt from The Island, only shown without sound.
The two programs differed enormously in terms of visual stimulation: The Island averaged 24.7 camera cuts per minute, while the interview show averaged only 4.8. Sound-source fluctuation was also far higher for the film.
As the researchers suspected, participants whose eyes and ears were overwhelmed were most likely to chow down. Those who watched the film excerpt (with sound) ate nearly twice as many grams of food than those who watched Charlie Rose. They also consumed 65 percent more calories.
Even while watching the silent version of The Island, and thus receiving visual but not auditory stimulation, participants ate 36 percent more grams of food than those watching Rose, and consumed 46 percent more calories.
"The more distracting a TV show, the less attention people appear to pay to eating, and the more they eat," the researchers conclude.
So it isn't just that television viewing is, by definition, a sedentary habit. Or that commercials can coax us into craving unhealthy foods. Watching a fast-moving program with rapid cuts—which defines a whole lot of today's content—leaves us largely unaware of just how much we're stuffing into our mouths.
The obvious answer—one that should be disseminated by physicians and health educators—is that eating and television viewing should be separate activities. Unless, that is, you're enjoying the relaxed rhythms of a public television interview show.