Teamwork on a Screen

Does Reducing Screen Time Reduce Obesity?

It seems pretty clear. Increased screen time correlates with a higher risk of obesity. In children and teens, for example, a recent systematic review and meta-analysis told us the risk goes up by two thirds with more than two hours daily. Recent prospective research links high screen time with BMI going higher a year later. All of this is certainly consistent with the experience in two years of the pandemic. Kids have been glued to screens because of remote learning and obesity rates for kids have risen.

So it follows logically that cutting screen time should help to reduce obesity. Right?

Well, not really. It turns out that this is one more case where conjecture needs testing and then the testing results don’t line up with our expectations.

A Meta-Analysis of RCTs

New in Preventive Medicine, Ping Zhang and colleagues have published a meta-analysis of randomized controlled trials of screen time intervention effects on obesity in kids. They analyzed the results of 14 studies with a total of 1,894 participants.

If the hope was simply to reduce screen time, the results are great. They show that interventions can reduce both total screen time, and television time in both children and teens. But if the goal is a reduction in obesity, the results are disappointing. It’s simply not there, as the authors conclude:

“There is no evidence that screen time interventions alone can decrease obesity risk in children and adolescents, though they can effectively reduce screen time.”

Rationalizing Null Results

It’s really hard to let go of convictions about what ought to work in reducing obesity. Public health officials tell us they know what works. Screen time reduction is core part of CDC guidance for preventing obesity in childhood.

But the truth is that screen time reduction might not yield a measurable benefit for reducing obesity. It can certainly have other benefits. Often it leads to increases in physical activity that have clear benefits for physical and mental wellbeing. So the work to limit screen time is far from useless.

To reduce the harm of obesity, though, we need to look for tools that have a measurable effect. Relying on what “ought to work” for decades now has only brought relentless increases in obesity and harm to health. It’s time to move on from old conjectures that haven’t worked out. With some serious curiosity, we can find a better way forward.

Click here for the new meta-analysis and here for perspective on screen time for children in the pandemic.

Teamwork on a Screen, photograph by Jan Faßbender for the Open Knowledge Foundation Deutschland, licensed under CC-BY 4.0

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March 22, 2022

One Response to “Does Reducing Screen Time Reduce Obesity?”

  1. March 21, 2022 at 11:07 am, John DiTraglia said:

    Yeah I wrote about how this is ridiculous a long time ago. But the converse – that obesity causes increased screen time – is plausible because of stigmatization and isolation.