Cleanses and Fasts

Come January many of us are looking for a fresh start. Clear out the cobwebs, dust off the running shoes and shed some pounds. These are all great goals but the method in which you do it makes a difference. People are often looking for the quick fix but with quick comes short term; hence why you keep making the same resolutions every year. Popular media seems to encourage cleanses, fasts and detoxes as the solutions to recovering from overconsumption of food and alcohol and promoting weight loss. However, the detoxification and cleansing claims on many of these products are unproven and in many cases, false. Cleansing is not likely to result in fat loss and may result in negative health effects such as diarrhea, abdominal discomfort, electrolyte imbalances and dehydration. More serious effect can be experienced by those with diabetes, kidney, heart or liver problems and pregnant women, children and people taking medications and herbal supplements.

Cleanses often involve withholding certain foods or fluids and consuming certain juices, fibres, herbs or laxatives. The rationale behind cleanses is based on an ancient theory that suggests we need to cleanse the body of residual feces and toxins found in the intestine. However, science has proven that the digestive system is perfectly equipped to do this on its’ own. People are often drawn to cleanses if they suffer from constipation, which can leave you feeling sluggish and headachy.  Constipation is a common problem in society due to a diet low in dietary fibre and fluids.

Fruit and Vegetable Cleanses

Certain fruit (grapefruit, orange, apple, cranberry) and vegetables (cabbage, broccoli, carrots, parsley, asparagus and celery) have been studied in rats on how they alter detoxification enzyme functions. These changes can affect how we metabolize certain medication. Changes in enzyme function can be achieved by eating the whole fruit or vegetable as well as by juices. Some risks with juice cleanses include diarrhea, distention, tooth decay, nutrient deficiency, protein deficiency and muscle loss. 


Laxatives result in significant water and electrolyte loss and minimal (4-12%) calorie excretion. A systematic review of the most successful weight loss methods showed decrease energy intake, behavioural changes (food logs) and physical activity were the most effective.


There are various concerns about fasting. Muscle loss is significant, even within the first 24 hours and increases throughout the duration of the fast. There is a reduction in immune function, a decrease in liver detoxification enzyme function, an increase in rate of headaches, increased insulin resistance, loss of body nutrients and a reduction in one’s ability to work and exercise.

The Bottom Line

There is insufficient evidence to recommend cleanses as a means for detoxification and fasting has been shown to be deleterious to health. If you feel you need a cleanse, do it naturally and without unproven potential risky ingredients. Increase whole fruit and vegetable intake, drink at least 2 litres of water/day, avoid alcohol, don’t smoke, avoid processed and packaged foods and be sure to include lean protein (either from vegetarian sources like nuts, soy and legumes and/or from chicken, fish, egg), go organic if you like and be active.


Natural Standard, an authority on integrative medicine, after review of the evidence behind detoxification, concluded: “The safety of detoxification varies depending on the methods being used, as well as the overall health of the person. Patients should talk to their doctors before enrolling in serious detoxification programs.”

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