The outgoing ITV presenter said he and his wife Catherine watched the teenager “shrink away before our eyes” as her weight fell to less than 6st.
And he said: “We thought we were losing her so we tried to get help, but there wasn’t really the help there.”
Mark, 58, said his daughter first entered a “bleak, dark world” while studying for her A-levels and within a few months was dangerously ill.
He said he and his wife, an A&E doctor, sought in vain to find the right sort of care and in the end looked after her themselves.
Speaking on a mental health special on Radio 4’s The World at One the dad of three, pictured below, said: “We watched someone very close to us go from a very bubbly, lively, bright person to someone that was hollowed out and dying inside.
“The whole question of mental health is not given the right priority in this country.
“It’s not given the same priority as other physical health issues and yet we’re fast entering a situation where there is an epidemic in children’s health.”
Mark, whose daughter fully recovered, added: “I just want to see mental health treated by governments as seriously as other issues.”
Health Secretary Jeremy Hunt admitted that provision of mental health services across the country was “very patchy”.