The region is spending £60m more a year than it receives in funding and income.
The figures are in a local NHS review which that found that services in the county were "struggling to deliver consistent, high quality care".
Changes suggested in the report include centralising more services in specialist treatment centres.
An example cited was the bringing together of cardiac services at the Lincolnshire Heart Centre, which opened at Lincoln County Hospital in 2013.
United Lincolnshire Hospitals NHS Trust, which runs the unit, said that "survival rates for heart attacks are now among the best in the country".
Other recommendations in the report include calls for more care to be provided outside hospitals and better communication and better sharing of medical records.
The report also claimed that "more funding would not deal with the challenges in recruiting professionals into key health and care roles, including nurses, GPs, radiologists, paediatricians and other professionals".
Dr Sunil Hindocha, chief clinical officer at Lincolnshire West Clinical Commissioning Groups, said: "What we know is if we carry on doing things in the manner we are, then Lincolnshire's healthcare system is simply not sustainable.
"It is clear we are not getting the best for the population under the current configuration."
The report will form the basis of a public consultation later in the year.

The Dons turned down an undisclosed bid for the 29-year-old, who has made 22 appearances this season, on Friday.
"It's one of those things. You put a value on a player and that's what happens," Warnock told BBC Radio Wales Sport.
"We are just weighing up two or three other players at the moment to see what we're going to do."
He continued: "We try to keep away from the last-minute deadline but I'm afraid it's always there. There's a possibility that we might make another offer."
Aberdeen manager Derek McInnes says he has told Cardiff to "be serious" with regard to the fee if they wish to pursue their interest in Hayes.
Meanwhile, Warnock revealed he was in talks to bring a Premier League goalkeeper to the Cardiff City Stadium, and said he would not have sanctioned former keeper David Marshall's move to Hull City last summer.
"If I had been here all season I would have desperately gone out of my way to make sure he didn't leave," he added.
"We lost two goalkeepers on the last day [of the transfer window] and didn't recruit anybody, which has really snookered me really.
"I've been looking to get a permanent goalkeeper in now, I've made two offers for players which have both been turned town and now I'm trying to get somebody on loan from the Premier League."
Lincolnshire's health and care system could see a £300m overspend by 2021, according to a new report.
[NEXT_CONCEPT]
Cardiff City boss Neil Warnock says the club may make another offer for Aberdeen winger Jonny Hayes.