The GL Diet Cookbook: Over 150 tasty recipes for easy weight loss. Nigel Denby

       Chapter 2 WHAT AFFECTS A FOOD’S GL?

      Portion Size

      To calculate the GL of a food you need three pieces of information:

      You then simply divide the GI number by 100, then multiply that figure by the number of grams of carbs in the portion.

       Example

      If a food has a tested GI of 50 and a 100g portion contains 10 grams of carbs:

      50 divided by 100 = 0.5

      0.5 x 10 carbs = a GL of 5

      If you eat two 100-g portions of that food, the GL would double to 10.

      The GL is a far more accurate reference than the GI alone because, it takes into account a food’s tested GI response in the body plus the size of the portion and how many carbs are in that portion. So it combines the quality of the carb as well as the quantity to give you the whole picture instead of just part of it.

      The GI of a food is the same whether you eat one portion or 10 (!), which makes it difficult to use as a weight-loss tool as it is completely unrelated to portion sizes – a key factor for weight loss and health.

      Portions are SO important – even when using the GL – so remember that just because 100g of a specific food has a low GL of 5, if you eat three portions of it the GL becomes 15 (i.e. moderate).

      By understanding the GL of foods and choosing mainly low-GL foods, you can eat more food overall in quantity – BUT it’s still not a licence to go bananas!

      Food Processing

      The way a food is processed affects its GL considerably.

      Generally speaking, the more processed, the higher the GL. The nearer a food is to its natural state, the lower the GL.

      Bread is a good example – the highly refined and processed, fluffy white breads have a higher GL than the wholegrain, darker dense breads.

      The whole grains in wholegrain bread slow down the digestive process, so we can say it is a SLOW carb food, whereas white refined breads are digested much more quickly, producing a sharp rise in blood glucose. We call foods like this FAST carbs.

      Similarly, the GL of an apple is low – but if you remove the peel, which contains a lot of fibre, and process it into a concentrated apple juice, the GL rises.

      Food Additives

      There are many E numbers and enzymes added to foods during processing, either to enhance taste or texture and/or to prolong shelf-life.

      We don’t know yet exactly how each of these additives affect the GL, but chances are they have an impact, so again, the less tampered with a food is, the better. If a food label starts to sound like a chemistry lesson…our advice is to leave it on the shelf!

      Cooking Methods and Times

      The GL has been shown to rise after a food is cooked, which makes sense as the food will generally become softer and more easily digested, meaning it will break down into glucose more quickly once eaten, causing a faster rise in blood sugar levels.

      Pasta is a good example. If you cook it until it’s al dente (firm to the bite), the GL will be lower than if you cook it until it is soft.

      Raw food is best wherever possible and safe. If you have to heat it, do so gently and don’t boil the life out of it or burn it to a crisp!

      Ripeness and the Age of a Food

      The more ripe or aged a food becomes, the more starches and sugars are released, so it makes sense that a new, baby potato has a lower GL than a large baking potato, and that a ripe banana has a higher GL than an under-ripe one.

      Eat baby vegetables when possible, and fruits when slightly under-ripe rather than over-ripe to help keep your GL score as low as possible for the day.

      Adding Acidity

      Tests have shown that if you add acidity such as lemon juice or vinegar to a high-carb meal it can lower the glycaemic response by up to 30 per cent. This is believed to be because acid slows stomach-emptying and therefore the rate of digestion.

      Red wine vinegar and lemon juice have been shown to have the greatest effect when added to foods. It is thought that the body’s low-glycaemic response to yoghurt and sourdough breads is due to their high acidity.

      Another good reason to use vinegar is that researchers in Sweden have found that vinegar may help us to eat less and reduce the cravings induced by blood-sugar spikes after meals. Interestingly, they found a direct link between increased vinegar intake and satiety (feelings of fullness and satisfaction) after eating.

      So, no excuses, get those fresh lemons and vinegars out, add some olive oil and start making a GL-lowering concoction…and no, before you ask, this doesn’t mean that you can now eat chips floating in vinegar with impunity!

      Fibre Content

      There are two types of fibre – soluble and insoluble.

      Insoluble fibre helps move bulk through the intestine, which together with fluid and being active helps relieve constipation and has been linked with a reduction in the incidence of colon cancers.

      Vegetables and many fruits and root vegetables contain fibre only in their skins, so try not to remove them wherever possible.

      When insoluble fibre is finely milled and processed it allows enzymes to cause rapid digestion, thus taking away the added fibre benefit. This is why you will find that some wholemeal breads, ‘brown’ breads, pasta and rice, despite looking less refined and being higher in fibre, have a very similar GL to their white counterparts.

      Wholegrains, flaxseeds and oat fibre are all good sources of insoluble fibre.

      Soluble fibre is a gummy mass when mixed with water, and binds with fatty acids which can help lower total and LDL (‘bad’) cholesterol, reducing the risk of heart disease. It also prolongs stomach-emptying and therefore your feeling of fullness. From the GL standpoint, it slows the release and absorption of sugars into the body and therefore helps regulate blood sugar levels.

      Soluble fibre is found in whole