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Prof Knowles, of the university economics department, was commenting at the Otago Global Health Institute's 10th annual conference, at the Dunedin Public Art Gallery, which began yesterday.
A total of 193 nations, including New Zealand, earlier took part in a United Nations-led process to develop the 17 ''Global Goals'' and 169 targets.
These followed the earlier millennium development goals, which ended in 2015.
Prof Knowles said there were positive aspects to the sustainable goals but ''there are too many of them''.
Vague wording meant some goals were hard to quantify, and to determine if they had ever been achieved.
''I still do worry that 17 goals is an awful lot to keep track of.''
Governments would ''inevitably'' start to prioritise them.
New Zealand had not yet developed an agreed measure of poverty, against which future progress could be monitored, he said.
His talk was titled ''Global Health Perspective: Do We Need the Sustainable Development Goals?''
Otago commerce division pro-vice-chancellor Prof Robin Gauld congratulated the health institute on its success in running 10 annual conferences.
A conference organiser, Prof David Fielding, of economics, said about 100 people had registered to attend, including 15 from overseas.
The conference, which was supported by the Otago Centre for International Health, had brought together a widely multidisciplinary group of participants to discuss international health issues, Prof Fielding said.