Starchy foods have long been considered by main in the medical profession as a benificial for of carbohydrate. As it is complex in nature so should take longer for the body to break down, plus it comes with useful vitamins and minerals...
But how slow does it realy realise into the blood? Some of the more traditional methods of serving potato release sugars in to the blood as fast as table sugar, scoring an alarming 97 on the (GI) glycemic index. The only role carbohydrate has in the body is to provide full for energy. If that full demand has been met, i.e. muscle and liver glycogen supplys have been met, the rest can only go one place, FAT CELLS.
All the minerals and vitamins provided by these food can be better sourced from other plates that do provide slow realse carbohydrate and less of it, or meats that provide proteins and fats that has many uses in the body and also slow stomach empting, thus keeping you 'fuller for longer'.
The worst offenders are grains and potatos. If you wish to loose weight lose these, we don't need them, only want them!