Sweet potato is a bad, high-GI food? I don't think so, it is in fact the complete opposite.

It's not a matter of whether you like them or not but their measure. With glucose as the reference load and measuring 100, Sweet Potato measures 54. The dividing line for good and bad was chosen at 50. That makes them bad and you wrong.

A sweet potato is bad? You've got to be kidding! A sweet potato is loaded with antioxidants, vitamins, minerals and fiber. A recent study has shown that sweet potatoes helped stabilize blood sugar levels and improve insulin response in animals. Also, a food's glycemic effect depends on whether it is eaten alone or with other foods. Judging a food solely by its glycemic index is bad advice.

perhaps considering only the glucose level of a food to determine its "badness" is a bit too simple ...

I read that a 3 oz. sweet potato's GI is 48 - making it on the high end of having a low GI.
I willing to believe this is wrong, but...

I read some literature about 'Glycemic Load' a while back, which seemed a more sensible way of going about things.

In testing GI, a portion of the food is usually used that contains 50g of carbohydrate, rather than 50g of the food.

To get the Glycemic Load, you divide the GI figure by 100 (to get a percentage) and multiply by the amount of carbohydrate in the portion - giving you the 'payload' that will effect your blood sugar.

For example: a 100g slice serving of Watermelon with a GI of 72 (above 50, so a 'bad food') and a carbohydrate content of 5g (it contains a lot of water) makes the calculation 0.72x5=3.6, so the GL is 3.6.

As I recall: A GL of 20 or more is high, a GL of 11 to 19 inclusive is medium, and a GL of 10 or less is low.

In this way, a lot of foods that weren't on the list get back on, and some that were on are sensibly removed.

This is very similar to how I understand the recomendations in the book 'Protein Power' that each meal is restricted to 10g of Effective Carbohydrate Content (ECC) per meal - which is the carbohydrate content of the food minus the fibre content(?).

Just some thoughts from an interested non-expert. Best to read around the subjects to get more clarity/accuracy on these concepts.

The dividing line for "low-GI" tends to be 55, putting sweet potato at the upper end of low. Besides which, it's not the GI of any particular food that is important, but the overall GI of the meal - which means you can mix a little medium/high-GI food with a larger amount of low-GI foods with impunity.

I can understand where you are coming from in this article, but your view is very close minded. You can't decide whether a food is good or bad for you based solely on it's GI number. Sure it is good to try and keep a balanced insulin level, but that doesn't mean you should only eat the foods that are "low-GI". If you do that it can lead to health problems as well, such as, a lack of certain essential minerals that many of the "high-GI" foods are loaded with. Also, eating too much protein can be very detrimental to your health. I know this is an old article, but just the fact that you cited the Atkin's diet makes this a very hard article to take seriously. Eating healthy is all about eating a balanced diet, this means you can and should eat anything you want, but you have to make sure you eat a variety, any food is alright in moderation, and any food can be harmful if eaten too much. Fish is great for you yet if eaten too often it can increase your mercury to unsafe levels which can lead to poisoning, neurological disorders, and just poor overall health. Eating healthy means eating variety. Besides, if I was to follow your advise then I could never eat pasta or a sandwich?