People with an eating disorder are nearly four times as likely to become addicted to exercise, according to a study.

The paper, published in Springer Journal, drew on data from nine studies covering a total of 2,140 people with a mean age of 25. Exercise addiction was defined as having an obsessive approach to fitness that could have a negative impact on someone’s health and social life.

NHS figures disclosed this week show hospital admissions for eating disorders have risen by 37% across all age groups in the last two years, from nearly 14,000 in 2016-17 to 19,000 in 2018-19.

Mike Trott, of Anglia Ruskin University in Cambridge, the lead author of the study, said the main purpose was to assess risk.

“We knew an unhealthy relationship with food means you’re more likely to have exercise addiction but no one had crunched the numbers on that,” he said.

“This will inform our next study, to create a measurement tool to catch people before they get full-blown eating disorders. It’s important people develop a healthy relationship with food. There is so much information out there that is frankly unhealthy, such as starve yourself for a few days. Or they tell you that you need to go on a juice diet. There are so many people trying to sell you that stuff and it makes it worse.”

The nine studies involved 1,732 people who did not show any indication of an eating disorder and 408 who did. “We did a comprehensive search and looked through an academic database. We found 1,000 studies and whittled it down to the studies that fit our criteria. Then we crunched the numbers and did meta-analysis,” Trott said.

The paper suggests exercise addiction could be more likely in those with eating disorders because of a fear of gaining weight. The authors also noted that these people scored higher on addictive personality measures and obsessive-compulsive behaviours.

The paper concluded: “Subjects with indicated eating disorders are over 3.5 times more likely to suffer from addiction to exercise than their non-indicated eating disorder counterparts. Due to the higher risk of mortality in subjects with eating disorders, this study adds to the evidence that exercise levels should be closely monitored in these populations.”

A quarter of the NHS admissions for eating disorders in 2019 were children aged 18 and under, including 2,403 for anorexia, up 12% from the previous year. This included 10 cases of anorexia among boys aged nine and under and six among girls of that age. The most common age for patients with anorexia was between 13 and 15.