How will a low GI diet help me to lose weight?

Thanks for your question. 

When talking about the glycaemic index of food, whether it is low or high GI, we are discussing how quickly these foods with carbohydrate break down during digestion, and how quickly the body’s blood sugar levels are measured as a result. 

High GI foods: Foods with carbohydrate that break down quicker during digestion and cause blood sugar levels to rise faster

Low GI foods: Foods with carbohydrate that break down slower during digestion and cause blood sugar levels to rise more steadily. 

This concept was developed to assist people with diabetes in choosing food options that would aid them in controlling their blood sugar levels more accurately. So how will using this concept assist in weight loss?

By choosing foods that have a lower glycaemic index, we are able to breakdown the food over a longer period of time, therefore your body would feel more satisfied for longer. This in turn ideally leads to less overall food consumed and eliminates unwanted craving and snack eating. 

However weight loss is attributed to being in a calorie/kilojoule deficit for food consumed and energy burnt (through a range of bodily mechanisms not just physical activity). You need to eat less than your body requires in order to lose weight. So whilst choosing foods which are low in GI, this does not translate to weight lost, as GI content measures the breakdown of food and effect on blood glucose, not directly the energy content of food. 

An example: A Low/Medium GI food option such as brown rice (55) is loaded with energy (calories/kilojoules) and choosing this option as oppose to a high GI food such as watermelon (75) would result in more energy being consumed thus could limit weight loss. 

So to sum up it’s great to use the glycaemic index scale as a tool or guide to foods, as lower GI foods are generally healthier with high levels of fibre than high GI foods, however by purely selecting low GI foods, won't necessarily lead to weight loss. 

Tim Jeans

To lose weight there are 3 components required. A healthy eating plan that meets you nutritional needs, being physically active as part of your daily life and finding solutions to personal barriers that may be making these lifetyle changes difficult for you.

The glycaemic index is used to help you choose the better carbohydrate foods ( e.g.breads, cereals, fruits, starchy vegetables and dairy products).Generally they are less processed and for cereal based foods are usually wholegrain with a  mix of cereal grains e.g.rye, oats, barley , wheat. However these also need to be eaten in the right amount to make up a healthy diet. Low GI foods should not be eaten ad libitum just because they have a low GI especially if you are trying to lose weight.  Foods that provide protein and essential fatty acids are also important and many vitamins and minerals as well. Sometimes foods that have a higher GI can also be eaten as part of a healthy diet especially if they are providing important nutrients for you but usually eaten in smaller amounts or part of a mixed meal or snack.

Low GI foods/meals are used for weight loss and general health as they generally make you feel fuller and because they are more slowly digested  you are less likely to feel hungry and less likely to over eat. However we do not eat carbohydrate foods in isolation most of the time, they are generally eaten as part of mixed meals and many components of the mixed meal can also lower the GI of the carbohydrate further for example adding low fat milk or yoghurt to a wholegrain breakfast cereal.

To lose weight it is important to understand the important foods and nutrients you need to eat in the correct amounts each day to meet your body's nutritional needs, within the right energy/calorie/kilojoule intake for you to achieve your goal. Remember healthy eating and being active is a life long goal for health not just for weight loss.

Elizabeth Newsham-West ( APD)

A healthy low GI diet will help you to lose body fat by:

a. Overcoming hunger: Because low GI foods take longer to digest, they make you feel satisfied for longer and trigger natural appetite suppressors.
b. Fat burning: Reducing insulin levels over the course of the day which makes fat easier to burn and less likely to be stored.
c. Maintaining your metabolic rate: a low GI diet does not result in the same steep fall in metabolic rate which is the body’s natural response to the large drop in food intake required by most quick-fix diets. You need to keep your engine revs high to lose weight and keep it off.