Low GI diet for weight loss and blood sugar control

The Glycaemic Index (GI) was created as a way for diabetics to know which foods will affect their blood sugar but it can go far beyond this in helping all of us to make healthier decisions with food.

Adopting a diet that focuses on low GI foods can have numerous health benefits, including helping to maintain stable blood glucose levels and controlling appetite.

What is the GI?

The GI rates foods in line with their effects on blood glucose levels. The scale runs from 1 to 100 and is based on how quickly carbohydrates are broken down into glucose.

Glucose is therefore the benchmark by which all other foods are measured against and it scores the maximum of 100 on the scale.

At the highest end of the scale are carbohydrates that are quickly and easily digested. This leads to a rapid rise in blood sugar levels, followed by an increase in insulin levels.

At the lowest end are carbs that take a lot longer to be digested. They release energy on a more gradual scale, which helps to stabilise blood sugar.

Another factor that affects GI is the presence of a starch called amylose in relation to another starch called amylopectin. Foods that have more amylose rank lower than foods that contain more amylopectin, which is why potatoes are high GI compared to lentils.

How do low GI foods affect blood sugar and weight?

A low GI diet can promote weight loss, largely because it helps you to feel fuller for longer and curbs cravings, meaning that snacking is much less likely.

Low GI foods don’t cause such a big rise in glucose compared to high GI foods. This is important for weight loss as it also means that the body doesn’t need to produce as much insulin to bring blood sugar levels down again, as is the case when high GI foods are consumed. The body’s craving for more food is reduced with low GI foods as there aren’t the same fluctuations in blood sugar and insulin and levels of both are a lot more stable.

Which foods are low GI?

Foods are classed as low GI if they rank 55 or less on the GI scale. They include:

  • Most fruits and vegetables are low GI, especially non starchy types such as leafy greens, broccoli, spinach, green beans, peppers and artichokes. The main exceptions to this are potatoes, parsnips, sweetcorn, apricots, watermelon and dried fruit
  • Porridge (not the instant type) and muesli
  • Whole grains, rye bread and most breads made from multi grains
  • Yogurt and milk
  • New potatoes
  • Buckwheat
  • Nuts and seeds such as chia seeds, flax seeds, pumpkin seeds and walnuts
  • Avocado
  • Honey.

Which Foods are High GI?

Foods that score 70 and above on the GI index are considered high GI and they include:

  • Dates
  • Watermelon
  • White bread
  • Baked and mashed potato
  • Most types of white rice
  • Parboiled rice.

There are also medium GI foods that score between 56 and 69 on the scale. These include pitta bread, rye crisp breads (similar to Ryvita), couscous, basmati rice, brown rice, pineapples, raisins, melon and apricots.

Tips for following a low GI diet

  • Aim for at least one low GI food in every meal
  • High GI foods aren’t necessarily out of the question as you can downgrade a meal to medium GI by teaming a high GI food with a low GI food or adding some protein into the equation
  • Bigger meals will increase blood glucose, even if the ingredients are low GI
  • Limit the amount of processed, refined starches and products made with white wheat flour, especially ones that are lacking in fibre. Examples of this can include white bread, white rice and white pasta. Swap these for lower GI alternatives such as whole grains, brown rice, brown pasta, rye and porridge
  • Increase your intake of beans, legumes and lentils - adding them to soups, casseroles, chilli and even salads are easy ways to do this
  • Swap creamy salad dressings for vinaigrette - the latter has less fat and the extra acidity slows down digestion so the meal is lower in GI.

Meal ideas for a low GI diet

Some of the ways that you can put this into action include:

  • Breakfast choices - porridge with a drizzle of honey; muesli topped with blueberries; yogurt with apple pieces
  • Lunch - a medium portion of beans or lentils with a salad and vinaigrette dressing; vegetable soup with lentils and a slice of wholegrain bread
  • Dinner - fish with new potatoes, peas and tomato; basmati or buckwheat rice; chicken breast and green vegetables
  • Snacks - a handful of seeds or nuts; a pear; a dark rye crisp bread.

The views expressed in this article are those of the author. All articles published on Nutritionist Resource are reviewed by our editorial team.

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Bournemouth BH2 & Amersham HP7
Written by Anita Bowes, On-line Registered Dietitian & Nutritionist, MSc, BSc, PGDip
Bournemouth BH2 & Amersham HP7

Anita is a registered dietitian. She gained in depth experience in nutrition working in her private practice and for over 12 years as a clinical & research dietitian. She has led cutting edge research into developing new approaches to weight loss and management of diabetes with several high level publications under her name.

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