The Autumn Statement will include a £150 million investment in treatment for children and young people with eating disorders.
Deputy Prime Minister Nick Clegg said he had secured the funding, which will be rolled out the next five years, to stem the growing numbers of children as young as five being admitted to hospital with disorders such as anorexia, bulimia and binge-eating.
The Deputy Prime Minister, who has long campaigned for mental health services to be given parity with physical care, said he wants the money to support early interventions and community-based treatments, and to lead to the development of waiting time and access standards for eating disorders by 2016.
"Too often, children with mental health problems are being completely let down, with many suffering from eating disorders that go unreported and untreated," said Mr Clegg.
"We know that if an eating disorder goes untreated for more than three to five years, the chances of recovery are greatly reduced, while incidents of self-harm increase.
"That's why we need to act now to transform the current system, intervening earlier with dedicated and targeted community-based services to ensure that we don't fail this generation or the next."
Anorexia kills more people than any other mental health condition, with up to 20% of those suffering from the condition dying from it, said Government sources.
People aged between 14 and 25 are the most likely to be affected by an eating disorder, and it is believed that as many as 1.1 million people in the UK may be directly affected.
A report by the Health and Social Care information Centre in January found an 8% rise in hospital admissions for eating disorders in the 12 months to October 2013, with the largest rise among youngsters aged 10-19. The most common age for female admissions was 15 (300 out of 2,320 cases) and for males 13 (50 out of 240 cases).
The new investment will support schemes to ge t young people with eating disorders and self-harm early access to services in their communities, making hospital admission a last resort.
Access to talking therapies will be extended and there will be an end to the current "cliff-edge" transition to adult services when young people with eating disorders reach 18, said Mr Clegg.
Care minister Norman Lamb said: "I want to build a fairer society and that's why I'm determined to make sure children and young people get the best possible mental health care. That's why I convened a task force of experts to focus on improving services. Better care for eating disorders is a top priority and this investment will help drive up standards so that no child is left without support."