Naturopaths have long promoted liver cleansing diets, but it was not until Dr Sandra Cabot published her best selling book, The Liver Cleansing Diet, that most people had heard of this type of dietary program.

The advocates of liver cleansing claim that liver dysfunction can have symptoms ranging from poor digestion and headaches to sugar cravings, high blood pressure and weight gain. These claims may sound believable, but does a dirty liver really cause all these health problems and should we be recommending liver cleansing diets for weight loss?

Do I need to clean my liver?

There is plenty of evidence to show that the amount of fat in the liver can build up in people who are either diabetic, grossly overweight, have had hepatitis, or drink large amounts of alcohol. However, there is no evidence that the major cause of weight gain is liver dysfunction. At major obesity conferences around the world researchers are focussing their efforts on genetics, diet and physical activity as the key factors influencing weight gain. Dirty livers don't rate a mention, which simply reflects its low importance as a weight loss treatment.

You don't have to do anything special to clean your liver for general health. You can keep your liver and other organs functioning properly by living a healthy lifestyle; in other words, by limiting your alcohol consumption, being active and maintaining a healthy weight. These have long been the components of sensible weight management programs.

Are liver cleansing diets healthy?

Most liver cleansing diets are fairly healthy, but the reasoning behind them is often flawed. For example, many of these diets claim that drinking water or eating enzymes in fresh fruit will help weight loss. This is not true. The table below summarises the common dietary claims for liver cleansing and the evidence to support these claims. Most of the data available on liver cleansing is based on anecdotal evidence only, which means that without controlled research comparing people on the diet versus people on a control diet, it's difficult to evaluate the effectiveness of the claims.

The cleansing approach often recommends increased consumption of fruits and vegetables, which is to be commended. It's the omissions that are of concern. Dairy foods are often dumped from the diet. If this leads to a calcium deficiency it could contribute to calcium loss from the bones, resulting in earlier osteoporosis. The importance of physical activity for weight loss is also often missed.

Here's a list of common cleansing claims and the evidence to support them.

Water cleanses the liver and kidneys, aiding weight loss.
Drinking fluids is good for hydration and water does clean the kidneys. However, water has no effect on weight loss.

Dairy foods are bad for your system and should be avoided.
Some people have lactose intolerance, where their body doesn't produce enough lactase (the enzyme that digests lactose). They may have to limit their consumption of milk, but not necessarily cheese or yoghurt. The bacteria naturally present during fermentation use most of the lactose in these products. Soy milk, which is naturally lactose-free, is another alternative.

An even smaller number of people are allergic to the proteins in dairy products, but for most of the population dairy foods have no side effects. Low-fat options are recommended to help cut back on saturated fat.

Sugar intake must be reduced because it is the main cause of weight gain.
Dietary fat has more energy per gram than sugar and is more easily converted into body fat, so the fat we eat is the main dietary influence on fat stores. For people who eat a lot of sugar, a reduction may be warranted, but as a lower priority.

Essential fatty acids help weight loss.
Essential fatty acids, including the omega-3 fats are an important part of a healthy diet, but there's no evidence to show that adding small amounts to a regular diet - such as eating seeds - will aid weight loss. If you eat too many handfuls of seeds, the extra fat may contribute to weight gain.

Fresh fruits and vegetables contain living enzymes that enhance digestion.
Any enzymes present in fresh produce are destroyed by stomach acid anyway.

Why do people say liver cleansing works?
If you consume less energy by eating a diet with less fat, alcohol or sugar, chances are you'll create an energy deficiency in the body and lose some weight. Liver cleansing diets, with their pro-fruits and vegetables and anti-junk food prescription can deliver this outcome.

When people succeed at weight loss it's common to give all the credit to the book they read or the program they joined without questioning its scientific foundation. Liver cleansing becomes popular when people think they fixed their liver rather than their eating habits. It's the dietary changes that bring the results and clients should be praised for this.

The bottom line is that liver cleansing diets may help people eat mostly the right things, but for the wrong reasons. There's little if any scientific evidence that provides a link between a dirty liver and excess weight or cleansing the liver and weight loss. Promoting healthy, balanced eating and a regular exercise program are still the most sensible weight loss guidelines.

Originally published in the January 2001 issue of the Australian Fitness Network Magazine