How many teaspoons of sugar in a boiled potato?

A 150g boiled white potato is about one medium potato. Dr Unwin’s charts list it with a glycaemic index of 96, the highest GI of any food in this dataset. It appears on two charts, common foods and fruits vs vegetables, and both give the same GI, weight and teaspoon figure.

A GI that high means that in the tests averaged in the international tables, gram for gram of carbohydrate, the potato’s starch raised blood glucose nearly as much as pure glucose. Potato starch swells and softens readily in boiling water, which makes it easy for digestive enzymes to break down.

Neither chart prints a glycaemic load, so the load on this page was back-calculated from the teaspoon figure.

Potato GI values are among the most variable in the tables. Variety matters: waxy new potatoes and floury baking potatoes behave differently. So does preparation, and boiled, baked, mashed and instant potato all appear with different values. Cooling cooked potatoes forms some resistant starch, which is sometimes reported to lower the response, though none of Dr Unwin’s charts measures a cold potato.

On the fruits vs vegetables chart, boiled potato heads the vegetable rows. Food guidance differs between countries on where potatoes belong: the UK’s Eatwell Guide groups them with starchy carbohydrates, while US guidance counts them as a vegetable. This dataset lists them under staples.

A baked potato, with its own figure from the 2016 paper, is on the baked potato page, and oven-baked french fries come from the common foods chart.