More than half of children growing up in America today could be obese by the time they are middle-aged, according to new projections.

Harvard University’s TH Chan School of Public Health found that 57% of US children will be obese by the time they are 35 years old, in part because of increased childhood obesity rates.

“It’s definitely a shocking and sobering number,” said Zachary Ward, the lead author on the study. “But if you look at trends in weight gain over the past 40 years, it’s not too surprising we’re heading in this direction.”

“This could just become the new normal the way things are going,” Ward said. “There are areas of the country among some subgroups where we’re already approaching this level of obesity.”

Researchers at Harvard used body mass index, or a measure that uses height and weight to determine whether a person is obese, to develop a model using the data of more than 41,000 children between two and 19 years old.

The study used data from five studies that nationally represent the US population in 2016. Researchers then made “virtual populations” of more than 1 million children who were 19 or younger. This was done 1,000 times.

Some of the study’s most startling findings were for children considered severely obese. Children in this group were more likely than not to remain obese by age 35. Researchers described the trajectory of risk as “striking”.

“A two-year-old who is obese is more likely to be obese at 35 years of age than an overweight 19-year-old,” the study found. A child who is severely obese at age two has only a one-in-five chance of not being obese by 35. By age five, that chance is halved to one-in-10.”

The worldwide obesity rate has doubled since 1980, and the United States has the highest rates of obesity among high-income countries. Currently, about one in three American adults are considered obese, and about one in seven children.

“We’re having to learn how to treat hypertension and lipidemia and Type-II diabetes in kids,” said Dr Chris Bolling, a pediatrician in Kentucky and an expert in childhood obesity who was not involved in the study. “That’s new territory for pediatricians.”

Between 1990 and 2010, obesity among children grew 60%, according to the Harvard TH Chan School of Medicine. In 2010, 43 million preschool children in the US were considered overweight or obese.

Obesity is defined as having a body mass index of 30 or higher, a measurement that uses a person’s height and weight to find a numerical representation of whether they are at a healthy weight.

For example, the Centers for Disease Control and Prevention considers a person who is 5ft 9in and between 125 to 168lbs a healthy weight. The same person weighing 203lbs or more is considered obese.