From time to time I get asked about cleanses. What is typically meant by a “cleanse” is only drinking a juice concoction for several days. Some cleanses add things like cider vinegar, cayenne pepper, or other supposedly “healthy” substances.

The most common reasons to “cleanse” that I hear from people who drink these things include:

• Lose weight
• Feel better
• Remove “toxins”

Let’s start with weight loss. Cleanses are very low calorie and don’t contain protein in any substantive amount. Consuming far fewer than 1,000 calories a day of juice is not a recommended weight loss strategy. At all. Cleanses typically put you in the starvation range of calorie intake and there is a mountain of evidence based medicine to show that this is not an effective part of any sound eating strategy. There are some medically supervised liquid weight loss programs that are very low calorie (in the 700-800 range), but the liquid is true meal replacement meaning it has a balanced nutritional complement. I have heard some weight loss experts suggest these types of programs can be helpful for people who are experiencing severe obesity-related complications and need to start getting weight off as fast and as safely as possible.

Will I feel better? Well, that’s a hard one to quantify given the placebo effect. If you think you are going to feel better, you probably will. Positive thought has a positive impact. Some people report feeling incredible on a cleanse, even euphoric. An excellent quote on this comes from Marjorie Nolan (by way of the Boston Globe, and read the whole article):

The euphoria and mental clarity that many juice fasters report on the third day of the fast isn’t about good health, Cohn says, but a result of simple starvation. “At some point your body shuts down that feeling on immediate hunger, you become lightheaded and dizzy, and that euphoric feeling starts to come on,’ she says. “I work with a lot of anorexics, and they feel euphoria too.

Will a cleanse remove toxins? First of all, what is meant by toxins? Remember, “toxins” is not a medical word and using quasi medical speak is a classic strategy of snake oil salespeople. Do you mean urea? Biliverdin? Carbon dioxide? These are normal in our blood, yet dangerous in high amount if the kidneys, liver, lungs, or circulatory system are not in good working order. Technically, blood isn’t “cleaned” in the way we clean a counter top. The liver, kidneys, and lungs remove waste products by specific mechanisms and the waste chemicals exits our body through the appropriate chute (bowel, bladder, or respiratory tract). The system is well-designed to use what we need and dump the rest. When people develop renal failure, liver failure, or heart failure harmful substances can easily accumulate, but this is not fixed by cleanses. If cleanses truly removed anything that was potentially harmful we’d be using them instead of dialysis for kidney failure and no one would ever need a liver transplant. Want your liver, kidneys, and lungs to remove waste more efficiently? Exercise, because increased blood flow and a healthy heart and blood vessels are the cornerstone of organ health.

A cleanse is about as healthy as a pedicure, meaning it isn’t. At all. Pedicures have health risks. Ask anyone who has ever worked on a plastic surgery ward. They can lead to devastating infections, because the foot is a a terrible place to get an infection. I know this fact, yet I still get pedicures, because I like painted toe nails and the foot massage is nice. I chose a salon that sterilizes equipment, but I accept there are still risks and I’m not kidding myself that getting a pedicure is anything but a cosmetic procedure. A pedicure doesn’t make me healthy, only pretty (in my mind anyway) and gives me a feeling of being pampered.

So if a cleanse makes you feel pretty or pampered, then great. Have at it. Just understand that it is not healthy in any way based on our understanding of anatomy, biology, or physiology and the only thing that a cleanse is truly cleaning is your wallet. At least with a pedicure you actually get clean feet.

Jennifer Gunter is an obstetrician-gynecologist and author of The Preemie Primer. She blogs at her self-titled site, Dr. Jen Gunter.