The earthquake and tsunami which hit eastern Japan in March 2011 killed thousands, displaced whole communities and destroyed towns as well as catastrophically damaging nuclear reactors in Fukushima. Now, according to a new Japanese government report, its effects are making children fatter.

Radiation fears have meant that fewer children are playing out or taking part in sports and other activities that are part of a healthy lifestyle, a report released this week by the education ministry says.

It surveyed the heights and weights of 700,000 children between the ages of 5 and 17 and found that Fukushima registered the highest rate of obesity in seven of thirteen categories. Comparing Japan’s 47 prefectures and defining obesity as weighing 20% more than average for their age and height, the report also said that Fukushima had previously only topped one category, that of the 10th graders.

“The amount of exercise has declined in Fukushima, mainly among elementary school pupils, as outdoor activities in some locations have been restricted after the Fukushima Daiichi nuclear plant accident,” a ministry official told a news conference.

In Fukushima, 56% of public schools (449 schools) curbed outdoor activities during school time as of June last year due to radiation concerns, Kyodo news agency reported, adding that restrictions were still in place at 71 elementary and junior-high schools as of September this year.