Jack Perry, former chief executive of Scottish Enterprise, told MSPs all areas should be addressed. His comments follow warnings from financial watchdog Audit Scotland which called for "different and radical" thinking on looming spending cuts.
Addressing Holyrood's finance committee, Mr Perry said: "What I get a little bit concerned about occasionally is the 'sacred cows' – saying that we will not touch health spending, we will not touch education."
Labour, Conservatives and the SNP have indicated they want to protect key areas such as health spending while trying to claw back money elsewhere.
Mr Perry said: "Lower spending does not necessarily mean poorer services. In fact, if you can eliminate unproductive processes, if you can re-engineer those processes, you can actually get a better service for less spend. You have to look at better ways of delivering a service. Just throwing more money at it has not delivered higher productivity."
The committee is investigating the Scottish Government's budget strategy for 2011-12.
Auditor General Robert Black earlier wrote to the committee warning the drive to make 2 per cent efficiency savings will not be sufficient in future.
Reports from his office have already commented on the "emerging gap" between public spending and budgets, forecast to be between 1.2 billion and 2.9bn in 2013-14 if spending continues at present rates.
Yesterday Mr Black said his message is "pessimistic" and highlighted reports from other bodies which put the gap between 2.1bn and 3.8bn.
He added: "Most experts are thinking a more pessimistic scenario is more likely than an optimistic scenario. Take that as a starting point."