Abby Lee Miller is proof that prison does a body good.

The disgraced Dance Moms diva, 51, posted a photo on Instagram yesterday showing off her dramatic weight loss and according to celebrity nutritionist Charlene Ciardiello, Miller has lost 95 to 100 pounds!

However, Breaking Celebrity News has exclusively learned that it wasn't dancing or fitness that helped Miller shed the weight.

"Abby Lee isn't exercising at all in jail," said a source close to FCI Victorville, the federal prison in California where Miller is currently servicing a 366-day sentence. "But she eats very little. She stays holed up in her cell and avoids going out into the public areas and engaging with the other women. In fact, she is rarely seen eating at all!"

In addition, Miller has had more than a little help from surgery. Prior to her sentencing in April – when Miller was found guilty of bankruptcy fraud – she revealed to Entertainment Tonight that she underwent gastric bypass, a procedure that reduced her stomach by 80 percent.

Though Miller looks fantastic in the picture, she may not look quite so amazing in person. According to celebrity photographer and photoshop expert Alan Barry, Miller's photo has "definitely been altered."

"Her chin line now qualifies her for her own cartoon series. Even assuming she has lost weight, either she had plastic surgery during her incarceration, or someone edited this photo to remove all the skin from her jowls, chin line and upper neck," Barry told Breaking Celebrity News.

Celebrity photographer Gil Cortes agreed with Barry.

"The most noticeable and obvious sign that it has been retouched is that there is a lot of discoloration around her jawline in this photos," Cortes added.