The Wall Street Journal earlier reported, citing people familiar with the matter, that the company met with a range of firms to gauge their interest in a buyout that could be worth up to $4 billion including debt.
The company's market cap is about $1.4 billion.
Potential buyers include Fosun Group, a conglomerate, and investment firm ZZ Capital International.
The buyers could be looking to cash in as Chinese consumers become more conscious of their health and diet choices, the Journal noted. If any of these buyers make a successful bid - and that's not near guaranteed - it would be the most prestigious purchase by a Chinese buyer in this industry.
GNC shares collapsed 25% on July 28 after the company announced a sudden CEO change amid a drop in sales. Michael Archbold left after two years at the helm and was replaced by board member Robert Moran.
This chart shows GNC's rise in trading on Wednesday:
