The 43-year-old Oscar winner has filed legal documents against Sensa Products executives, accusing them of breaching contract by manufacturing allegations against her and terminating a deal, the Hollywood Reporter said.
Spencer alleges she agreed to promote a "healthier lifestyle" for the company as part of a USD 1.25 million deal, but told bosses that she would not pose for before and after photographs and wouldn't appear in tabloid magazines or websites.
After honouring her side of the agreement and actually losing weight by using Sensa products, Spencer claims the campaign flopped and the company's bosses attempted to cut her from the deal.
In legal papers filed in Los Angeles, the actress' lawyers state, "Sensa manufactures and markets a diet product designed to trick one's brain. Therefore, it's not surprising that it would manufacture allegations against its most prominent spokesperson, Octavia Spencer."
Spencer opted to add the hashtag to her endorsement tweets to adhere to new regulations from Federal Trade Commission, which call on celebrities to "disclose their relationships with advertisers when making endorsements outside the context of traditional ads, such as on talk shows or in social media."