The GI is a measure of how quickly or slowly the carbohydrates in foods are broken down and converted into glucose. A low GI recommends foods that release sugars slowly.
People sometimes confuse a low GI with a low carbohydrate diet. Low GI it’s not about avoiding carbs, it’s about using so-called ‘slow’ carbs. It is about the quality of the foods instead of avoiding one whole group of nutrients (carbohydrates).
Not all foods with a low GI are healthy. For example, watermelon and parsnips are high GI foods, while chocolate cake has a lower GI value. Therefore, making decisions on GI value alone is not a 100% fail-proof way to judge whether a particular food is right for you. Watermelon is unprocessed. Chocolate cake is highly processed. Which one is a better choice?
A better way is to choose foods that are both unprocessed and low GI. When you need to decide what whole foods to eat like fruit, vegetables or grains, a GI index can still be handy because you can choose the healthier option.
Another handy measure when using low GI foods is the glycemic load. It gives you a more accurate picture of how specific foods will impact your blood sugars.
If we take watermelon as an example again. It has a high glycemic index of 80. But it contains so little carbohydrate that its glycemic load is only 5.
A practical strategy for a low GI diet is to substitute high-GI foods (refined grains, potatoes, sugars) with high-fat foods (nuts, seeds, avocado, olive oil) getting carbohydrates from whole grains, fruits, and legumes and non-starchy vegetables.
Subtle changes – a big difference
As you can see, the difference between low GI and usual diet is nothing too crazy. There are subtle changes, like swapping, higher GI foods to lower ones: whole-meal bread with whole grain bread or having an apple instead of banana.
|Low GI Plan||Conventional Healthy Plan|
|Breakfast||1 cup Kellogg’s Guardian cereal||1 cup Kellogg’s Bran Flakes|
|200 mL low-fat milk||200 mL low-fat milk|
|1 medium orange||1 cup diced rockmelon|
|Snack||1 medium apple||1 medium banana|
|Lunch||2 slices Tip Top 9-Grain Multigrain bread||2 slices wholemeal bread|
|50 g tuna in spring water||50 g tuna in spring water|
|1 cup salad vegetables||1 cup salad vegetables|
|50 g avocado||50 g avocado|
|Snack||2 Ryvita Multigrain Rye Crispbread||2 whole-meal crispbreads|
|2 Tbsp hummus||2 Tbsp hummus|
|4 slices tomato||4 slices tomato|
|Dinner||100 g lean pork||100 g lean pork|
|2 cups mixed vegetables||2 cups mixed vegetables|
|3/4 cup Asian noodles||3/4 cup Sunbrown Quick rice|
|1 tsp olive oil||1 tsp olive oil|
|1 tsp soy sauce||1 tsp soy sauce|
|Snack||150 g low-fat fruit yogurt||150 g low-fat fruit yogurt|
|1 small pear||1 cup diced watermelon|
|Dietary fiber (g)||34||32|
1 LGI, low glycemic index; GI, glycemic index; CHO, carbohydrate; GL, glycemic load.
The above meal plan has some issues. Namely the use of low-fat dairy and breakfast cereal. Studies have shown that full-fat dairy is actually better for ovulation and breakfast cereals should be avoided.
The above graph shows the scale of improvements women recorded themselves eating low GI (LGI) vs conventional healthy diet (CHD). A higher column reflects a greater change in each domain.
In this study, better blood sugar control helped more women to ovulate regularly. Furthermore, this way of eating reduces inflammation.
We should not forget that in this study authors compared two rather healthy food plans. I assume the difference would be even more dramatic if women were allowed to have what they usually eat.
How low GI diet helps fertility
A recent systematic review and meta-analysis compared how low GI weigh up to High GI diets for overweight women with PCOS. Low GI won in all key areas:
- better blood sugar regulation and improved fasting insulin levels;
- improved blood lipids;
- lost weight, especially around the waist and,
- decreased Testosterone levels.
Low GI is the best fertility diet for most people, but especially for women with PCOS
Low GI foods improve fertility for all women, not only PCOS.
Low GI was equally beneficial for women with and without PCOS. 80% of women with erratic menstrual cycles resumed regular menstruation after a 24-week calorie-restricted low GI eating plan. Study participants lost weight and their bodies controlled sugar better.
The benefits of a low GI diet for fertility
- Optimises ovulation and cycle regularity
- Reduces insulin sensitivity
- Helps to lose weight
- Reduces inflammation
- Reduces testosterone levels
Low GI diet resources
If you are ready to give low GI foods a go, a good place to start is the website of the University of Sydney. Here you will find low GI food recipes, ingredient swaps and get plenty of inspiration.
A searchable database for low GI and GL fertility foods is here.