Commercial websites are designed to sell products, which is why they are generally not considered a credible source of information for the purposes of research.
Science is generally done at educational institutions as well as through recognized scientific organizations and publications.
So yes, there are some commercial sites which might be considered credible, because they are run by credible publishers like Nature Publishing Group, which runs the peer-reviewed journal www.nature.com and the popular science magazine www.scientificamerican.com.
But some commercial website, hawking a diet, is not a credible source.
It is impossible to prove that a substance does not cause cancer. Your argument is invalid because there is no food in existence which we can show absolutely does not increase cancer risk. What we can say, for example, is that extensive testing has been done on substances like aspartame with no clear evidence of any increased cancer risk in humans. We cannot say, by contrast, that extensive testing has been done on organic apples or most other "natural" foods, since only artificial substances require testing to be approved for human consumption.
It is simply an illogical argument you are making because it could be made for absolutely any food or substance. If you are claiming that it increases the risk of cancer, the onus is on you to back up your beliefs by citing high quality peer reviewed research.
The scientific consensus is not that aspartame causes cancer and I defy you to actually provide valid evidence to support your claim. The scientific literature clearly shows the opposite is true. [1] Also, your claims about aspartame's insulin boosting effects is based on a small number of pilot studies, not on large scale, high quality human studies showing a real-world negative effect on human health. There is no compelling scientific evidence to demonstrate that aspartame actually causes weight-gain and I would defy you to provide it if you believe otherwise.
Finally, as I already stated, this commercial website you keep raving about is not a credible source. I am not going to waste my time reading random internet websites. You need to support your claims with credible science published in legitimate peer reviewed journals and you need to make a proper citation to the actual paper, journal, title, and date, not just say, "look at this diet website that is selling diet products". That is not a credible reference.
It is not my job to "google" scientific data to support your claims. That is a shifting the burden of proof logical fallacy. It is the job of the person making the original claim to provide credible evidence to support it, and in the case of science, that means citations to peer-reviewed publications, not writing , "Google it", or "look at this website selling diet products".
For instance, here are a couple of properly cited scientific references from the article I used as my source:
Council on Scientific Affairs. Aspartame: review of safety issues. JAMA. 1985;254:400-402.
European Food Safety Authority. Opinion on a request from the European Commission related to the 2nd ERF carcinogenicity study on aspartame. 2009. Accessed at www.efsa.europa.eu/en/scdocs/scdoc/945.htm on April 13, 2010.
Notice how the first one properly cites a publication in one of the world's most respected peer-reviewed medical journals and the second one properly cites a publication of the European Food Safety Authority. If I were to follow your example, I might just cite www.sugar.org. If you want to talk about science, you need to actually read and cite credible scientific sources, not diet websites.
SOURCES:
[1] http://www.cancer.org/cancer/c...