Cooking techniques and food pairings can affect how quickly carbohydrates raise our blood sugars – Elettra Scrivo writes.

Most of us know that if we eat something sweet, our body gets sugar. Yet even savoury foods, such as starchy carbohydrates, can have the same effect.

Whether it’s baking, boiling or frying, how we cook carbohydrates can make all the di­fference, impacting the glycaemic index (GI), meaning how quickly foods cause blood sugars (blood glucose) to rise.

Baking food

Baking food, which often takes longer than boiling or frying, can result in a higher GI.

Ovens also reach higher temperatures than frying pans or steaming pots, which — as with cooking time — causes starch molecules to break down into sugars.

These, when consumed, are then broken down further by our pancreatic enzymes and converted into glucose.

For the e­ffect that carbs can have on some of us (and not everyone responds the same to carbohydrates), baking could almost be likened to turning starchy foods into confectionery, explaining their sweeter taste.

Leftover pasta

Preparing starchy carbs a day ahead can help to lower the GI. When we boil rice, pasta or potatoes, it induces a process of gelatinisation, which disrupts the structure of the starch complex.

If eaten straight away, these starches would be easily digested and converted into glucose. But when we leave the food to cool, a type of fibre called resistant starch is formed.

This ‘resists’ digestion in the stomach and travels to the large intestine, having less of an impact on blood sugar levels, and becomes food for our gut bacteria, as an added bonus.

So when we eat cold pasta, rice or potatoes, not all of the original carbohydrate converts into glucose.

Reheating chilled pasta, rice and potatoes — and even toasting frozen bread — can reduce the GI even further.

How bad is fat?

Whilst low fat foods are often lower in calories, they may also cause blood sugars to rise more quickly, triggering a di­fferent pathway to weight gain.

Meanwhile, as the plethora of one-spray cooking oils shows, fear of dietary fat has turned many of us off­ using it in cooking.

However, cooking with fat, adding fat such as olive oil or butter before serving, or pairing carbohydrates with a source of fat (e.g. cheese, nut butters or avocado) may contribute to slowing down the digestion of starches.

However, despite the temptation to choose fried foods, it’s worth remembering that GI doesn’t tell us everything about nutrient content.

Baked potatoes, for example, may have a higher GI than a bag of crisps, but won’t contain potentially inflammation-promoting seed oils or artificial flavourings.

Many factors to consider

How quickly food causes blood sugars to rise (the GI) can be influenced by a variety of factors.

For example, a green banana has a lower GI compared with a ripe banana, because ripeness makes sugars more available to digestion — which is why ripe fruit is sweeter.

Food composition (e.g. high or low fat or fibre) also has an impact.

Fat and fibre slow down digestion, and also help to lower the GI of a food. So, for instance, wholegrain rice will have a lower GI than long grain white rice, and a plain, full fat yoghurt will have a lower GI than plain, low fat yoghurt.

Partnering high fibre carbohydrates with fat and protein should help to reduce the GI impact of meals.

However, how quickly our blood sugars respond is also dependent upon our own health status and genetics.

If you are concerned about your blood sugars, it is important to seek medical advice.

What to do:

  • Be wary of baking your carbohydrates.

  • Don't be afraid of leftovers!

  • Pair with healthy fats, protein and fibre-rich foods.

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Learn more about blood sugars in this article about insulin resistance

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