Data shows that only 20 per cent of youngsters received a routine appointment in four weeks in the first quarter of 2017-18 and 40 per cent in the second quarter.
For urgent appointments, 66.67 per cent of people were seen in a week in quarter one and zero in quarter two.
But the target is for 95 per cent of patients to be seen within those timeframes by 2020.
Other news: Green light for Wigan's £15m NHS planNorth West Boroughs Healthcare NHS Foundation Trust, which runs the service supporting young people with eating disorders, says the percentages are affected by the low number of patients needing treatment.
Dr Sandeep Ranote, consultant psychiatrist and eating disorder lead at North West Boroughs Healthcare, said: “We place great importance on providing a high-quality eating disorder service to children and young people across Wigan and Bolton.
“The Wigan data reported relates to small numbers of people – between one and five patients – which significantly impacts the overall percentages. In addition, the figures do not take patient choice into account – for example where a family is unable to attend an offered appointment within a week of referral.”
Steps have been taken to cut the waiting times and appear to be making a difference, with more patients seen in time in the third quarter of the year.
Dr Ranote said: “We acknowledge waiting times for this service need to improve and have taken action to make sure this happens.
“We reviewed and compared the service with a similar eating disorder service we deliver across Mid-Mersey to share and implement good practice.
“We have doubled the number of weekly new patient appointments available where possible, recruited to vacant posts, increased staff training, changed processes to offer more flexibility for families and improved consistency of data collection.
“The impact of these improvements is beginning to show, with 100 per cent of urgent new referrals seen within one week between October and December (quarter three) and 50 per cent of new Wigan referrals seen within four weeks during the same period (60 per cent across Wigan and Bolton).
“We continue to work closely with Wigan and Bolton clinical commissioning groups, which commission the service, to identify opportunities to improve the service, meet growing demand and meet the 95 per cent target set nationally to be achieved by 2020.”