A morbidly obese 10-year-old boy died after his drug-addicted parents allowed his weight to balloon to 80 kilograms, and Community Services failed to effectively intervene to stop the neglect, a coroner has found.

The child, referred to as "AA", was declared brain dead at Newcastle's John Hunter Hospital on September 29, 2010, following catastrophic cardiac arrest stemming directly from breathing apnoea related to his obesity.

In handing down her findings into the death in Newcastle on Friday, Coroner Elaine Truscott found that AA's parents had been repeatedly told that the child could die if he didn't lose weight, but they continued to feed him junk food and skipped numerous medical appointments.

Both had spent more than a decade on the methadone program and his mother was addicted to amphetamines.

Coroner Truscott also found that multiple reports about this medical neglect of AA had been made to the local Community Services office, but that the child was not allocated a case worker due to a combination of staff shortages and a lack of co-ordination with the hospital.