1. Potatoes Potatoes are inescapable. It is the 4th most eaten vegetable in the world and is considered to be the ultimate comfort food for many. Sadly, they are not that great health wise. Did you know that just a cup of this starchy vegetable has the same effect on blood sugar as a can of cola. Loaded with carbs, they are digested in such a way that causes rapid rise in blood sugar levels. They are also a common culprit of obesity, diabetes and various heart diseases. Potatoes are not all bad. They contain some amounts of Vitamin C, Vitamin B6 and Potassium but they are also packed with calories.