Eating to win: activity, diet and weight control
Eating to win: activity, diet and weight control

Start this free course now. Just create an account and sign in. Enrol and complete the course for a free statement of participation or digital badge if available.

5.1 The role of the glycaemic index

The glycaemic index (GI) describes the rate at which carbohydrate foods are digested (broken down into glucose) and enter the bloodstream as glucose. You may already be aware of GI in the context of weight loss diets and healthy eating. The GI also has an important role in maintaining energy levels for physical activity and sports performance. The GI is a ranking of foods from zero to 100, based on the rate at which a carbohydrate food is broken down into glucose and enters the bloodstream, resulting in a rise in the blood glucose level. Pure glucose has a GI of 100 and serves as a reference point to which all carbohydrate foods are compared. A food that has a GI of 55 or over is regarded as high GI and food that has a GI of less than 55 is regarded as low GI (The University of Sydney, 2017).

Figure 5 shows the change in blood glucose levels over time in response to the intake of high and low GI foods. Click on High GI and Low GI for an explanation of each one.

Active content not displayed. This content requires JavaScript to be enabled.
Figure 5 Blood glucose levels over time in response to low and high GI food
Interactive feature not available in single page view (see it in standard view).

Some examples of high, moderate and low GI foods are shown in Table 2.

Table 2 High, moderate and low glycaemic index foods

High GI Moderate GI Low GI
Glucose 100Cornflakes 81Potato (boiled) 56
Parsnips 97Chips 75Sweet potato 54
French baguette 95Bagel 72Bananas 52
Lucozade Original 95Watermelon 72White pasta 50
Honey 87Wholemeal bread 71Muesli 49
Potato (baked) 85White bread 70Porridge oats 49
Sports drinks 70Baked beans 48
Weetabix 66Apples 38
White rice 64Yogurt 36
Shredded Wheat 64Chickpeas 28
Raisins 64Whole milk 27
Cherries 22
Fructose 20
(Source: Adapted from Bean, 2006)

Take your learning further

Making the decision to study can be a big step, which is why you'll want a trusted University. The Open University has 50 years’ experience delivering flexible learning and 170,000 students are studying with us right now. Take a look at all Open University courses.

If you are new to University-level study, we offer two introductory routes to our qualifications. You could either choose to start with an Access module, or a module which allows you to count your previous learning towards an Open University qualification. Read our guide on Where to take your learning next for more information.

Not ready for formal University study? Then browse over 1000 free courses on OpenLearn and sign up to our newsletter to hear about new free courses as they are released.

Every year, thousands of students decide to study with The Open University. With over 120 qualifications, we’ve got the right course for you.

Request an Open University prospectus371