1 September 2019



STEP 1: KEEP PORTIONS MODERATE. Why? Potatoes are carb rich. A typical medium potato (150g/5oz) has around 20g carbohydrate to help power your day. They are what we call good carbs – they put a lot of really good stuff on your dinner plate like dietary fibre and essential micronutrients including vitamins C, B (B6, riboflavin, thiamin and folate) and the minerals potassium, magnesium, and iron. The easiest way to keep an eye on portion size, is to eyeball the serving sizes by dividing the dinner plate into three sections. Protein foods (1) and wholegrains/starchy foods (2) should each take up just a quarter of the plate. Cooked green veggies or salad veggies (or both) should fill the remaining half (3).

Healthy plate
STEP 2: CHOOSE A LOWER CARB POTATO. There are some varieties of potato with fewer carbs. We sourced five packaged brands with about 20–25% less carbohydrate than regular spuds. Because growing conditions affect the carb content, the producers test their spuds regularly to ensure they meet the lower carbs claim on the packaging.

POTATO Table 1
Catherine Saxelby at Foodwatch did some experimenting with Carisma and Spud Lite and reports they are good all-rounders for family fare: they boil, mash and bake nicely. Check out her reports on her website (see Read More). If you want to taste test: the team at GiLicious have shared a recipe with us which you can find in The Good Carbs Kitchen.

STEP 3: CHOOSE A LOWER GI POTATO. Most potatoes have high GI values averaging around 77 (globally). This is because whatever the variety, potato starch consists of amylopectin and amylose in a fairly constant ratio of 3:1. When we checked the database at www.glycemicindex.com; flicked through The Shopper’s Guide to GI Values, and trawled back issues of GI News we found one potato with a low GI and several with moderate values which are better choices for managing blood glucose.

POTATO Table 2
While the variety makes a difference, there are other factors that affect GI. Small, new season potatoes tend to have a lower GI than fully grown spuds left in the ground longer. The recipe changes things, too. Cooking spuds in their skins and serving them with a vinegary dressing lowers the GI. Mashing them with white beans does too as will letting them get cold and making a potato salad, thanks to the resistant starch factor. However, it doesn’t seem to make that much difference to the GI whether you bake, boil or mash a particular variety of potato.

STEP 4: WATCH THE GLYCEMIC LOAD. How high your blood glucose level rises and how long it remains elevated when you eat a food or meal containing carbohydrate depends on both the GI of the carbohydrate and the total amount of carbohydrate in the food or meal. We use the term “glycemic load” or GL to describe this total amount. You calculate GL by multiplying the GI of a food by its available carbohydrate content (carbohydrate minus fibre in the USA) in the serving (in grams), divided by 100 (because GI is a percentage).

A regular medium-sized (150g/5oz) boiled potato with a high GI (average 77) provides approximately 20g of available carbohydrate. Its glycemic load is 15 (77 ÷ 100 × 20 = 15). Eat two potatoes and that jumps to 30.

You can reduce the load by reducing the portion size of the potato, or by choosing potatoes with less carbohydrate, or potatoes with a low or lower GI.

  • A medium GiLicious potato which has a moderate GI (61) contains 15 grams of available carbohydrate. Its glycemic load is 9 (61 × 15 ÷ 100 = 9). 
  • A medium Nadine potato, which has a low GI (49) contains 20 grams of available carbohydrate. Its glycemic load is 10 (49 × 20 ÷ 100 = 10).
SPUD WATCH? As there are literally hundreds of commercially grown varieties of potatoes around the world, it's very likely there are other lower carb and lower GI spuds out there. We'll keep you posted as we find them. If you come across any, please let us know.

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