The actress has been shuffling her role as an actress and mother for quite some time. The star is appearing in the Broadways show 'All My Sons'.
The 30-year-old Holmes will perform in the final show of the play in New York next Sunday while husband Tom Cruise will be on his way to the Golden Globes ceremony in Beverly Hills, where he has been nominated in the 'Best Supporting Actor' category for his role in 'Tropic Thunder'.
Holmes is a fan of the bizarre herbal detox plan favoured by Scientologists and offered at their three Gold Base centres in California and New York.
"The Clear Body, Clear Mind plan utilises a regime of exercise, sauna sweat-out, vitamins and minerals to cleanse bodies of toxins," said a source.
"Katie is tired from balancing motherhood with her six-nights-a-week show and wants to get back into shape. The plan involves doses of the vitamin niacin to purify the body," the source added.