Fast forward

Fasting can be a powerful tool but it can also be dangerous when abused. Is there any scientific basis for the claims that fasts can remove toxins and destroy tumors? Or is it true that there simply is no evidence for the benefits of going on short or long term fasts?

Fasting has been touted as the 'oldest and proven remedy for disease.' Many sites claim that fasts will purify the body, rid disease, and eliminate cancer. Short-term 'cleanses' lasting anywhere from several days to a few weeks have become so popular that health stores now have entire sections devoted to 'fasting kits.' You'll find several claims that fasting is the body's natural way to eliminate toxins and that the absence of solid foods 'saves energy' for your 'elimination organs' (liver and kidney) because they can work 'without the burden of digestion.'

According to some nutritionists, the opposite is true. One article published at Tufts University states that the 'feeling of being weak and sick is actually a sign of your body's natural, emergency response in a period of stress.' In other words, you don't feel weak because you are 'cleansing.' Instead, you feel weak because you are placing your body under stress. The article goes on to explain that fasting creates a 'rather abnormal situation.'

Fasting and starvation are not abnormal for a large percentage of the world's population. Several studies do exist and provide valuable insight into what goes on during fasting. One study in Sweden found that people who suffer from hypolgycemia can 'fast without any metabolic or endocrine derangement.' (2) Another study of pregnant women who fasted during Ramadan found that the fasting 'did not have a significant effect on the neonatal birth weight.' (3) In fact, long-term dietary restriction between one to three months 'often significantly increased latency and reduced the incidence of cancer over the entire life span.'

While research suggests that moderate fasts or periods of extreme caloric restriction may help slow or reverse the symptoms of certain diseases they do not adequately understand the mechanisms by which this may happen. Most theories involve changes to metabolism (i.e. how the body receives its energy) and the release of certain enzymes and other chemicals. One adaptation is the use of fatty acids as an energy source. While the body begins to burn a large percentage of calories from fat the overall metabolism slows. Ketone bodies are produced. Ketogensis is normal, but accumulation of these bodies over time can create a state of ketosis. While not harmful in the short term, this can turn into a potentially fatal condition known as ketoacidosis. Total fasting or restricting calories to nothing but protein can therefore place more toxins in the body rather than eliminating them.

Fasting is often performed for weight loss. The impact of fasting on weight loss differs between individuals. For example, the impact of short-term fasting on protein metabolism has been shown to differ between lean and obese subjects. The obese subjects actually lost far less protein overall (in other words, muscle loss was not as much of an issue). (4) This doesn't mean that fasting is the best solution, however. Another study found that a 'low-energy protein diet is, as compared with the fast, a more physiological way to achieve weight reduction, in particular because despite weight reduction a positive nitrogen balance is achieved.' (5) In other words, having some calories will actually preserve and even promote lean mass even when the subjects lost the same amount of weight over all. This means that a restricted calorie diet will burn more fat than a total fast.

What about fasting for cleansing the body? While there is no scientific model to study the body, there is plenty of anecdotal evidence to suggest people may feel refreshed, energetic, and generally more in control of their nutrition after a fast. This is in contrast to the suggestion that fasting triggers the release of hormones that create cravings for salt and sugars. Who are you to believe? The only way to really know is to try. When a fast is performed under supervision and with prior clearance from a health professional, many individuals find that regardless of the scientific debates surrounding fasts, the spiritual and mental benefits far outweigh any negative side effects.

In summary,

1. Studies suggest that short term fasting and even prolonged caloric restriction is not harmful for healthy adolescents and adults
2. Some data suggests short term caloric restriction (1 - 3 months) may actually reduce incidence of cancer
3. Restricting calories for weight loss is more beneficial to obese individuals than lean individuals
4. Restricting calories and taking in significant protein will burn more fat overall than a total fast

Another benefit of fasting is that it helps break addictive cycles. Healthy individuals need not be concerned about fasting for spiritual reasons. Persons looking to lose weight, however, should consider restricting calories rather than going on a toal fast. A healthy lifestyle is built through changing habits and patterns and making small changes over time, not by completely eliminating food. There is no 'fast forward' button to building a lean and healthy physique.