Studies are showing that when it comes to blood glucose, it’s the roller-coaster ride (the sharp glucose spike and the degree of blood glucose fluctuation) after eating that’s the problem as it can damage the body, contributing to the development of chronic diseases, particularly atherosclerosis.
The American Diabetes Association still emphasises the amount of carbohydrate to optimise glucose control and slow the development of complications. However, the key finding of this latest study backs up the growing body of evidence suggesting that if a reduction in postprandial glycemia (high glucose after eating) is to be part of the strategy for preventing and managing diabetes and cardiovascular disease, the GI (or carb quality) is just as relevant as carb quantity.
Prof Jennie Brand-Miller
Prof Jennie Brand-Miller’s GI team at Sydney University’s Human Nutrition Unit drew on their database of 1126 foods tested since 1995 to explore the association between a food’s GI and the shape of the curve in healthy young people (average age 24, BMI 22). The study is a first in a couple of ways – to attempt to systematically characterise the relation between a food’s GI and other attributes of post-meal blood glucose and to explore differences in the shape of the curve within and between food categories.
‘From the standpoint of defining what’s “normal” postprandial glycemia, our study is unique,’ says Prof Jennie Brand-Miller. ‘Our results suggest that the “normal” response depends on the choice of carbohydrate food. Our study’s key take-home messages are that:
- The GI reliably predicts the glycemic response, and the overall shape of the post-meal glycemia curve is similar for high, medium and low GI foods. Since they say that a picture is worth 100 words, check out the curves (incremental blood glucose profiles if you want to be technical) for high medium and low GI white breads, breakfast cereals, potatoes and pasta, soft drinks, wholegrain breads, rices, cereal and protein bars, fruit and juice.
- To control high blood glucose after meals, carb quality (or its GI) and carb quantity both count. So the general message is say “less” and say “low GI” with carb-rich foods.
- The simple “eat more wholegrains” health message needs fine tuning. Just telling people to “eat wholegrains” can encourage them to eat carbs with a high GI on par with white bread (GI 70). So it’s not an ideal message for helping people manage blood glucose spikes. It’s the low GI wholegrains with their gentler curves they need.’
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Shedding pounds without pangs
Eating ‘feel full’ foods that satisfy appetite faster and keep you feeling fuller for longer, puts you on the path to shedding pounds effortlessly without pangs. Research shows that when we consume foods (not beverages) that our bodies really notice we are eating, our gut and intestines (see below) send the brain the vital ‘I’m full’ signals. There’s quite a range of ‘feel full’ foods to choose from including:
- Foods that we have to chew a lot like lean meat, pearl barley, muesli, very grainy breads, apples and carrots.
- Protein-rich foods (lean meat, fish, chickpeas, nuts) that encourage our stomach and small intestine to produce hormones that send ‘I’m full’ signals to the brain. There’s added value with these too – they make you hotter after eating, which uses up more energy.
- Slow digesting low GI carbs can also increase the production of some ‘I’m full’ hormones and help keep our blood glucose steady after eating. In a recent study from the University of Sydney’s Human Nutrition Unit in the European Journal of Clinical Nutrition, lead researcher Rebecca Reynolds reports that ‘eating lower GI meals throughout the day produced significantly lower glucose and insulin concentrations along with higher concentrations of the satiety (fullness) hormone, cholecystokinin (CCK), compared with high GI meals’.
- Foods that have lots of fibre and water (high volume foods) deliver the ‘I’m full’ feeling. This is because volume, especially ‘sticky’ volume, like porridge means that food really touches the gut walls and leaves the brain in no doubt that it’s there. They also stick around the gut longer clinging to the walls.
Feel full foods are perfect for slim budgets too. You’ll find you can eat better for less when you cut back on modern refined foods. The body just doesn’t seem to pick up so well on the presence of these foods that are high in fat (the least filling macronutrient) and quick digesting carbs, which makes it hard to know when to stop eating. When these processed foods are around en masse encouraging us to eat more at each meal and eat more often, it’s hard for the body to regulate its weight.
GI Group: ‘How we make decisions to start and stop eating is a complex process. Your gut and brain “communicate” to determine when you are full, with your brain sending out the all important Stop Eating signal with the help of information it receives from hormones produced by your gut,’ says researcher Rebecca Reynolds. ‘Appetite is orchestrated by a part of your brain called the hypothalamus. It receives signals from the gut via the blood and spinal cord. Within about 15–30 minutes after you start eating, satiety (fullness) signals are transmitted from your small intestines. These act as a sedative on the gastrointestinal tract, slowing down the passage of food and creating a sense of fullness. However (there’s always one of those), keep in mind that psychological factors such as boredom, unhappiness, temptation etc. also influence your food intake and can overpower signals from the hypothalamus.’
Low GI diets better than high cereal-fibre diets for managing diabetes
A healthy, low GI diet achieved a greater improvement in blood glucose and cholesterol levels than a healthy, high cereal-fibre diet in people with type 2 diabetes report Canadian researchers in the prestigious Journal of the American Medical Association. Simply eating more dietary fibre is not enough to improve diabetes management is one of the study’s key findings.
Two hundred and ten overweight Canadian volunteers with type 2 diabetes (average age 60 years) who were being treated with anti-hyperglycemic medications were randomly allocated to go on to either a low GI diet (average GI 44) or a high cereal-fiber diet (average GI 61) for 6 months. The moderate carbohydrate (200 grams a day), moderate fat (60 grams a day), moderate protein (40 grams a day) diets were matched for kilojoule (calorie) intake and changes in blood glucose and other measures of diabetes management were recorded at regular intervals. (The low GI diet emphasised foods like pumpernickel bread, bulgur-and-flax breakfast cereal, and peas, lentils, and nuts; the high-cereal-fibre diet emphasized whole-grain breads and breakfast cereals, brown rice, and avoidance of starchy foods.)
At the end of the study, those on the low GI diet showed greater improvements in average blood glucose levels and good cholesterol (HDL). Glycated haemoglobin or HbA1c decreased by 0.5% points on the low GI diet compared with only 0.2% points on the high cereal-fibre, higher GI diet. HDL levels rose on the low GI diet but fell on the standard high cereal-fibre diet. ‘Improvements like these in blood glucose control would reduce the risk of common complications of type 2 diabetes like eye and kidney disease by up to 12%, and the risk of heart disease by up to 20%,’ says Dr Alan Barclay, Chief Scientific Officer of the GI Symbol Program.
No need to drop dairy foods
Dairy foods are often among the first to be struck off the shopping list by dieters, especially women. A recent study funded by the National Dairy Council and published in Nutrition and Metabolism didn't find eating the recommended three servings of dairy food a day (1 cup milk or 1 cup yoghurt or a 42 g piece of hard cheese) made any difference when it came to helping people maintain weight loss, but it did show that they were able to consume more calories without gaining weight compared with people who consumed less than one dairy serving a day.
Australian Better Health ‘Measure Up’ initiative
Belly fat has been linked to an increased risk of heart disease and diabetes and now to early death according to a study in the New England Journal of Medicine. Researchers following some 360,000 Europeans in one of the largest and longest health studies in the world found that people with the most belly fat had about double the risk of dying prematurely compared with people with the least belly fat. Death risk increased with waist circumference, whether the participants were overweight or not.
The Australian Government is supplying tape measures as part of its ‘Measure Up’ campaign to drive home to Australians the scary facts about flab. For most Australians a waist measure of more than 94 cm (37.6 in) for men and 80 (32 in) for women means a risk of developing a lifestyle-related chronic disease such as diabetes or cardiovascular problems. The tape moves into the red (yes, they are colour coded) if it goes over 102 cm (40.8 in) for men or 88 cm (35.2 in) for women, indicating increased risk of chronic diseases like type 2 diabetes and heart disease.
Being overweight causes excess fat around your waist to coat your organs. This fat is called visceral or intra-abdominal fat. Subcutaneous fat is the fat right under the skin. Both types play a role in contributing to health problems, however intra-abdominal fat contributes more. It is not yet clear exactly what links intra-abdominal fat with chronic disease, but what is clear is that even a small deposit of this fat increases the risk that you will have serious health problems. So Measure Up, get active, eat better and reduce your risk.
The Flexitarian Diet
Dawn Jackson Blatner, RD, LDN
This is a flexible vegetarian nutrition plan that minimises meat without excluding it. We like it because there are no rules or restrictions. You just eat more plants during your regular meals. There’s a 5-week eating plan with 100 recipes (breakfast, lunch, dinner, snacks and desserts) including plenty of quick and easy ways with beans (canned of course). Love her motto, too: ‘Be good to the body you have and it will be good to you.’ Each recipe makes ONE serving. So if there’s two of you, double the quantities. It’s published by McGraw-Hill and available in bookshops or from Amazon.