Food manufacturers are using a loophole in trademark law to dupe consumers into thinking products high in fat or sugar are healthy, a study has found.

Consumer advocacy group CHOICE found almost half of the 200 products with natural or healthy sounding names it reviewed had high levels of either saturated fat, total fat, sugars or sodium.

Health food ... or is it? Credit:Quentin Jones

"Manufacturers are trade marking healthy words such as 'natural', 'healthy' and 'fresh' to give the impression that a product is healthier than it seems," CHOICE spokeswoman Ingrid Just said in a statement on Wednesday.

Such misleading claims cannot be used to promote foods which are not healthy or fresh, but manufacturers can circumvent regulations by making bogus health claims in trademarked brand names, Ms Just said.