Potatoes are often perceived as unhealthy because they have a reported high glycaemic index (or GI).
HOWEVER, many nutritionists now believe the glycaemic index is not a very useful measure because it is a ratio that refers to the digestibility of carbohydrate relative to glucose, & does not reflect the density of carbohydrate in the food or the amount of food eaten to achieve a blood glucose response.
Glycaemic impact is a new way of measuring blood glucose response to food.
The advantage of this measure has gram units & can be expressed as g/100g of food or g/serving of food, just like other nutrients on a food label.
Potatoes are in fact an excellent source of low-density energy.
This means that the energy we get from potato comes from carbohydrate (17kJ/g) rather than fat (34kJ/g) & is diluted about eight times with water.
They are also a good source of vitamin C, a source of potassium & niacin, & if you keep the skin on a source of dietary fibre.
The glycaemic impact of potato is easy to manage in a healthy diet.
When potato is cooked the starch gelatinises & becomes digestible.
But when you cool cooked potato & let it stand for a while the starch chains partially join up, & this slows down the speed they are digested.
So starch in cold cooked potato is digested at a lower rate than in the hot potato, & correspondingly has a lower glycaemic impact per weight.
So potato is not the villain it has been made out to be because it is not carbohydrate dense.