Is the childhood obesity epidemic coming to an end?

March 7, 2017 - 06:20

After decades where rates of childhood obesity have soared, researchers now detect a clear decline in the percentage of boys who are overweight or obese in Sweden. A similar trend can be found elsewhere around the globe, including Norway.

Childhood obesity has been on the rise for decades in Sweden. But now it’s on the decrease, a new study shows. (Photo: Gustav Lorentzon, Maskot / NTB scanpix)

We’ve all seen the depressing numbers: the world is getting fatter and less and less healthy because of it. It’s a trend that has not spared our children. Images of baby-faced youths with inflated bodies like Michelin men crop up every time a new health study describes the increasing numbers of overweight and obese children.

Now, it seems, the tide may be turning. 

In Norway, the percentage of children who are obese appears to have stabilized and has decreased slightly among 8-year-olds, according to figures from the Norwegian Institute of Public Health.

“It’s too early to be very optimistic. But we can be cautiously optimistic,” says Pétur Benedikt Júlíusson. Júlíusson studies childhood obesity at the Children's Clinic at Haukeland University Hospital in Bergen and at the Centre for Morbid Obesity, Southern and Eastern Norway Regional Health Authority.

Norway is one of the countries in the OECD with the very lowest rates of childhood obesity. Nevertheless, it remains a big problem.

Between 14 and 15 per cent of girls and boys in the third grade were overweight or obese in 2015, according to the Norwegian Institute of Public Health’s Childhood Growth Study.

Sweden’s obesity numbers are also very low in the context of the OECD. Now the country can report a significant decline in the percentage of eight-year-old boys who are too heavy.

Lowest levels since the 1990s

After many years of rising rates of childhood obesity in Sweden, the proportion of children who are overweight or obese is at its lowest level since the 1990s, a new study shows.

Both the average BMI and the percentage of children who are overweight have dropped.

The numbers are from a study conducted at Sahlgrenska Academy in Gothenburg. The study is based on information that has been collected by the school health services, which have recorded the height and weight of children in Gothenburg every year since 1946.

A total of 13 age cohorts were included in the Swedish study. The age cohorts have been organized so there are five-year intervals between each group from 1946-2006. The initial study comprised only boys, but the researchers now plan to study girls as well.

Peaked in the 1990s

The rates of overweight and obesity among boys in Gothenburg were at their highest towards the end of the 1990s. Nearly 23 per cent of those who were born in 1991 were overweight or obese when they were eight years old in 1999. For children born in 2006, this number was 19 per cent.

When the researchers looked only at obesity during this same period, they found that rates dropped from 9.3 to 7.6 per cent.

Researchers have to use a different definition for overweight and obesity in children because they are growing and their body mass index, or BMI, changes gradually as they grow. For this reason, the researchers defined obesity in eight-year-olds as children who had a BMI higher than 20, while overweight was defined as a BMI of between 17.9 and 20. In adults, obesity is defined as having a BMI over 30, while overweight is defined as having a BMI between 25 and 30.

No answers as to why

The researchers have only studied the numbers, so they do not know the reasons behind the downturn.

Maria Bygdell is first author of the study and a doctoral candidate at the University of Gothenburg. She says that in spite of the positive findings, too many children still struggle with being overweight or obese.

Nevertheless, she says, the same trend showing a decrease in BMI in boys has also been reported in studies from Denmark, Scotland and Japan.

“I hope that what we see is a lasting trend,” she said.

Big social differences

Júlíusson, from Haukeland University Hospital, thinks the story is more nuanced.

“If you study the differences between social groups, the numbers look different. This is also true in Sweden,” he said.

“Obesity is a major problem for many children, and it looks as though there is still an increase in the lower social strata of society,” he said. “And there does not seem to be a decrease in kids who are the most overweight or obese.”

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Read the Norwegian version of this article at forskning.no

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