Jennifer Aniston, who is known for her super flat tummy, follows the Rhubarb smoothie diet, which includes drinking a smoothie after every meal. Also, the 'Bruce Almighty' actress has cut down on her carbohydrates intake.
It has been claimed that drinking a mixture of the blended fruit with guava and crushed ice helps to speed metabolism.
However Nutrition expert Amanda Ursell is at a variance with claims.
"There is absolutely no research to support the idea that rhubarb assists the metabolism in any way," The Sun quoted Amanda Ursell, as saying.
"But the real deal here is not the rhubarb, she is eating fewer calories through cutting down on carbs. This explains her flat tummy too," she added.
On the other hand popstar Mariah Carey, who says she invented the morsel diet revealed that she eats a tiny bit of everything.
"When I'm really, really hungry I'll say 'I need a morsel! So they'll give just me whatever is there [on the plate], but it has to be less than a forkful," she stunner said.
While Amanda has different take on that.
"Even if she did literally have anything she wanted, this diet would work because the portion sizes are so tiny, But I would be seriously concerned about her vitamin and mineral intake from this small amount of food," Amanda said.
"This is not recommended," she added.
Hollywood actress Reese Witherspoon follows the 'baby food diet', wherein she eats tiny portion of food.
"But this diet is so restrictive, not to mention impractical. The likelihood is that you wouldn't stick to it," Amanda said.