Our body's have their own detox systems, and we even detox in part from the foods we eat. For example algins and pectins from seaweeds, fruits and vegetables will bind and remove heavy metals. Phytic acid from grains also have a higher affinity for heavy metals than it does nutritional minerals. And silica from fibers can help displace lead and some other toxic metals. Fibers can also help in the removal of other toxins. Sulfur from diet can also help the body detox. These are just a few examples. So the body is constantly in a cycle of uptaking or creating toxins and breaking down and eliminating toxins. Sometimes though the toxic load can exceed the body's ability to break down and/or eliminate toxins. This can lead to health issues or even increased fat production as the body stores the excess toxins in fat until they can be processed and eliminated. This is why people tend to become sick when they first start on strict fasts. As the body breaks down the body fat the stored toxins, such as heavy metals, herbicides and pesticides get released back in to the bloodstream.