A new diet book is on the shelves called Six Weeks to OMG: Get Skinnier Than All Your Friends. It's creating some discussion on whether it's actually healthy.
Apart form the cold baths and the coffee, the diet also says people should avoid fruit juice, broccoli, starches and carbohydrates.
Ashley Simper is a dietitian at OSF Saint Francis Medical Center. She says it's just another fad diet.
"Things like the cold bath and the coffee, probably not going to hurt anybody, but you definitely don't want to teach people to skip meals or to avoid certain food groups. That does not establish good eating patterns," Simper said.
The diet promises people can lose 20 pounds in six weeks, but Simper said that healthy weight loss is much slower, one to two pounds a week.