A number of studies have found detrimental links between the rate at which pesticides are released from the body during weight loss, and a person's metabolic rate afterwards. Additionally, pesticides and industrial pollution have been found to lower metabolic rate by their affect on thyroid hormones and the rate at which the liver excretes them. And this is the tip of the proverbial iceberg.

What does all this mean?

To understand why this occurs, it is helpful to learn a little bit about environmental toxins in the body. Whilst detox experts include metabolic by-products and a number of other things such as medications, alcohol, tobacco, and the like in the list of culprits that contribute to the effects of toxicity in the body, the studies I saw cited environmental toxins only, so I will limit my discussion to these. That is not to say that these other things aren't potentially causing problems for an individual, only that they weren't in these studies.

Environmental toxins include organochlorides, which come from pesticides, and PCB's, which are leaked into the environment from industrial pollution. Pesticides make it into our body via the food we eat, and are also found in many of the chemicals we clean with and use in the garden. These toxins are stored in our body in fat cells. So, people who have a higher body mass index, store a greater amount of toxins.

When we lose weight, the fat cells are metabolized, or broken down. This releases into the body any toxins stored there. Thus, if you lose a lot of weight, you release into your body's circulatory system a greater amount of stored PCB's and pesticides.

How Do PCB's And Pesticides Affect Metabolism?

A number of studies cited in an article in Nature and Health (Feb/Mar 2007) describe the way in which metabolism is negatively affected:

* damage to the mitochondria. Mitochondria are energy producing 'powerhouses' in all cells. In the liver, and muscle tissue they convert fat into energy.

* reduction of thyroid hormone levels. Thyroid hormones contribute to the basal mnetabolic rate, and are particularly involved in fat and carbohydrate metabolism.

* an increase in the excretion of thyroid hormones by the liver

* these toxins have an affinity with the receptor sites where thyroid hormones need to attach in order to produce their regular metabolic effects

* these toxins also use the transport proteins that thyroid hormones need to use in order to get to these sites

* blocking the effects of the hormone, leptin, that signals that you are full. Thus, you may think you're hungry even when you're not and overeat as a result.

Unfortunately, simply burning off fat is not enough to stop the effects of PCB's and pesticides. They can affect your metabolic rate even after you've lost weight, if you don't also excrete the toxins. And because of the inhibitory effect they have on metabolism when overweight, they can contribute to a weight loss plateau.

There are a number of things you can do to detoxify your body however. This includes adding herbs, vitamins, and steam baths or saunas. Saunas are actually a very effective way to eliminate toxins. A daily sauna session of 15 minutes, at 60 degrees celcius in a far-infrared sauna, can reduce both body weight and body fat, as well as excreting environmental toxins through the skin.