The Royal College of Paediatrics and Child Health is urging parents to look out for signs of eating disorders in children and young people.
Its snapshot survey suggests in some parts of Great Britain doctors have seen a three or four-fold increase in cases compared to last year.
Specialists say the pandemic is a major reason behind the rise.
NHS England says though record numbers are getting care for eating disorders, more will need support.
The Royal College of Paediatrics and Child Health heard from around 40 specialists working in England, Scotland and Wales who said they had seen a rise in referrals.
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The organisation says many factors are involved – including isolation from friends during school closures, exam cancellations, loss of extra-curricular activities like sport, and an increased use of social media.
Fears about the virus, family finances, and students being forced to quarantine may also have contributed.
And doctors say in some cases, reduced access to face-to-face consultations may have led to young people becoming severely ill by the time they were seen.
The anecdotal reports suggest in some areas waiting lists are “completely overwhelmed” and beds “increasingly scarce.”