It found "very large implementation gaps in several important areas", including the absence of a comprehensive national plan to tackle obesity, policies to reduce marketing of junk food to children and ensure healthy food in schools, or to tax unhealthy foods.
New Zealand rated alongside Australia as setting an international benchmark in ensuring that unhealthy foods do not carry health claims, and scored well in providing ingredient lists and nutrition panels on packaged foods.
However, the areas where New Zealand was doing "very little, if any" far outweighed the "high" scores, which showed we were doing "extremely badly in relation to obesity", Mr Swinburn said.
"We really need to get serious about this. It's been tinkered around with, it hasn't really been taken with the seriousness it warrants.
"A lot of these things that are recommended don't cost much money, in fact some of them even raise money, like an excise tax on sugar-sweetened beverages," Professor Swinburn said.
The report highlighted 34 areas for improvement, with seven classed as immediate priorities.
All of the seven priorities were "eminently doable for a wealthy country with a big problem", he said.
Warren Lindberg, chief executive of the Public Health Association, said the seven recommendations would be "hard for Government because they ask them to do things that they're not comfortable doing, particularly putting tax on stuff and regulating business".
Sue Pollard, chief executive of the NZ Nutrition Foundation, said the report was a "great exercise", but many food policy decisions were based on politics.
Forming a comprehensive national plan would be "a really important first step".
But Health Minister Tony Ryall said the Government had no intention of introducing more restrictive measures. He said the Government's role was providing information and support on healthy eating.
"We see our new $40 million anti-obesity initiative, Healthy Families NZ, as a more sophisticated and evidence-based way of addressing obesity and other underlying causes of poor health."