Trudeau, who lives in Oak Brook, a Chicago suburb, theoretically could be sentenced to life behind bars for the criminal contempt conviction though he's likely to receive a far less severe sentence. No sentencing date was set Tuesday.
Prosecutors say Trudeau violated a federal judge's 2004 order barring him from making false claims about his book "The Weight Loss Cure They Don't Want You to Know About," which topped best-seller lists.
During closing arguments Tuesday morning, prosecutor Marc Krickbaum accused Trudeau of lying repeatedly about the benefits of the book in his infomercials, which were ubiquitous on late-night television.
"He made the book sound way better than it actually was," Krickbaum told jurors.
But in his closing, defense lawyer Thomas Kirsch said prosecutors had failed to prove their case, noting they called just two witnesses. He said prosecutors also hadn't shown that any possible misstatements by Trudeau were intentional.
The core dispute revolved around dramatic claims in Trudeau's TV infomercials about the book, including that people who followed the diet need not exercise and could eventually eat anything they wanted without gaining weight.
The book describes a diet of 500 calories a day and the use of prescription hormones. The truth of the claims in the book itself weren't at issue only the veracity of claims Trudeau made on TV as he sought to persuade viewers to purchase the book.