AN ACADEMIC who complained to health authorities about a company that marketed a herbal spray as ''the most effective slimming solution available in the world today'' has failed to have an $800,000 defamation case thrown out.

Ken Harvey, an adjunct senior lecturer at La Trobe University in Melbourne and a regular campaigner against non-scientific products and services, has accused SensaSlim of stymying an investigation by the Therapeutic Goods Administration into its weight-loss product by launching legal action in the NSW Supreme Court.

The TGA's complaints resolution panel had received a number of complaints about the product, including those from Dr Harvey and Professor Lesley Campbell, from the St Vincent's Hospital diabetes centre, alleging that SensaSlim has made outlandish claims without scientifically acceptable evidence.

However, the panel is restrained from investigating the product while legal proceedings are under way.

''By having a legal case, they have totally stopped the complaint panel for at least a year but they can continue promoting and selling it and they are laughing all the way to the bank,'' Dr Harvey said.