You’ve probably heard or read about the GI diet and may even have dismissed it as yet another of those fad easy weight loss programs that doesn’t work. Most nutritionists agree however, this is far more than just an easy weight loss program and can form the basis of healthy eating for weight loss.
That should also help you develop and support a healthy lifestyle in the long term. This section introduces the GI diet and looks at how you can incoporate it into your daily life. So what is GI exactly? GI stands for glycaemic index and was originally developed in the early 80’s by a nutritionist who was studying how different foods affected blood sugar levels in people with diabetes.
He discovered that many starchy foods such as potatoes affected blood sugar levels dramatically whilst some sugary foods had little effect, which was the complete opposite to common understanding at the time. From this research he developed the glycaemic index (GI) which is a scale of 1 to 100 that describes the effect food has on blood sugar levels.
In simple terms this is caused by the speed at which carbohydrates are digested as most carbohydrate must be digested before they can get into your bloodstream in the form of glucose, rising blood sugar levels and therefore providing energy.
Therefore, a carbohydrate that is digested rapidly and creates a large increase in blood sugar levels, it is said to have a high GI. If, on the other hand, a high-carbohydrate food takes a long time to release a slow, gradual increase in blood sugar it is said to have a low GI. The basis of a low-GI diet in very simple terms can explained as eating carbohydrates with a low GI, however it’s not quite that simple!
How can a GI diet cause weight loss? When you eat carbohydrates with a high GI your blood sugar levels increase dramatically. When you have high levels of blood sugar your body releases a hormone called insulin, to remove the excess glucose and restore levels to normal.
The rapid release of insulin causes the following reactions:
Insulin takes away the glucose and stores it away in the body. The glucose is stored in the liver and muscles, but once these are full then it is converted into fat and stored in your fat cells. Because this causes a sudden drop in blood sugar levels the body then craves more high GI foods for another glucose high. This is why you may still feel hungry after eating certain foods or why one biscuit may not be enough.
When you eat low GI foods on the other hand, blood sugar levels raise gradually which only cause a small amount of insulin to be released slowly. A small amount of insulin tends to make you feel full and causes the release of a hormone called glucagon which has been described as the ‘fat burning’ hormone.
Eating low GI food will therefore help you burn fat and keep you feeling full for longer, thus reducing the overall amount you eat. High GI foods cause your body to store fat and leave you craving more food. However fat content of a food should also be considered as many low GI foods have a high fat content which most GI diets recommend cutting down on so choose your low GI food carefully!
The Glycaemic Index of different foods: There are many different places to find the GI values of particular foods and they will list different foods by category. Most will categorize food as low when it has a GI of 55 or less, medium as 56 to 69 and high as 70 or above. Each GI diet food list may differ slightly but they should all be fairly similar.
You may find yourself surprised at the values of certain food that you had always considered ‘healthy’ for example a lot of breakfast cereals have a very high GI whereas chocolate is low. Several things affect a foods GI; for example fat and protein will affect the absorption of carbohydrate which explains why chocolate is so low.
Other foods have a low GI because they have high levels of fibre which also slows down the absorption of carbohydrate into the blood. Processing, cooking and even the ripeness of fruit all have a bearing on it’s absorption into the bloodstream and therefore it’s GI.
The GI of a meal may be different to the individual elements of the meal
Unlike calories, the overall GI of a meal is not a simple sum of its parts. Eating a meal that has different foods of different GI values will have an impact on the overall GI of the meal.
Eating a mixed and varied diet is important for overall health however so do mix different foods together still. As a basic rule the more low GI foods you include in a meal the lower the overall GI value of the meal. For example including oatbran with your foods helps lower the GI value of just about anything.
The downsides to Gi diets
One of the greatest problems with the GI diet is the difficulty of assessing the true GI value of the meals you eat and the fact that some low GI foods are not necessarily good for you as they are packed with fat or have little nutritional value.
It is possible therefore to follow a low GI diet that is actually bad for you, although a little common sense will probably tell you that. Most published GI diets will provide recommendations about what to eat and what to avoid and help with combining different food to make the plan work.
Benefits of the GI diet
Most GI diets will enable you to lose around one to two pounds per week if you want to lose weight. Following this type of diet may also help reduce the risk of getting Type 2 or maturity onset diabetes and research shows that low GI diets can help improve levels of good cholesterol, which may reduce the risk of heart disease.
Because the diet recommends eating plenty of food and vegetables and having a mixed and varied diet it should also help improve overall health as it should provide optimum vitamins, minerals and anti-oxidants which all help prevent diseases and general ill-health.
People on a GI diet often say they feel better in themselves, have less sugar cravings, mood swings and generally feel more alert. Because nothing is banned and the rules are really quite simple many people often find it’s easier to adopt as a lifestyle rather than just treat as a ‘diet’ for a few weeks. Take a look at our diet and healthy living resources