That seems a bit contradictory for weight loss products. Today, Aspartame seems to be the primary artificial sweetener. It is used in most diet pops, especially the big three. In addition, it is the sweetener of choice in many packaged food products, medications, supplements, and other items for human consumption. It is the NutraSweet, Equal, and Spoonful you find in most restaurant and grocery stores.
Methanol is a cumulative, human-specific toxin.
Your body does not have the necessary enzymes to detoxify it. It takes 5 times longer to eliminate than a similar amount of ethanol. This protection is absent with Aspartame. For your body to detoxify the wood alcohol in Aspartame, it must convert it to formaldehyde and then into formic acid. These are both toxic metabolites.