*Steve Harvey is attempting to lose 21 pounds in 21 days with a “magical” detox diet. But critics are saying the diet is dangerous and ineffective.

The diet, called “Lose 21 Pounds in 21 Days,” is based on best selling book by Roni De Luz and James Hester. The diet suggests people to sip fruits and vegetable juices every two hours fore three weeks. Dieters are not supposed to eat a bite of food the whole time. Only liquids.

So Harvey announced he’s going to do it to shed the pounds. Fans and followers can keep track of his progress via a website.

“You can’t live on a diet like this because it simply does not have adequate calories or protein,” says Anne Fletcher, MS, RD. “Not only does protein make you feel full longer, but solid food makes you full longer.”

And, she adds, liquids don’t provide satiety in the same way solids do. So then the deprivation factor enters into it,” she says. “How long can you stick with something that deprives you of so much?”

A diet that encourages only juice consumption is a recipe for failure, says celebrity nutritionist Christine Avanti. “Where is the fiber if everything is all blended up?” she says. “And fruit drinks can cause blood sugar to spike.”

She also added that when users go back to eating regular food, their metabolism is slowed and would cause them to regain the weight.