Carbohydrates can be found in various foods such as breads, cereals, fruits, vegetables, and dairy products, and they are essential for a healthy diet. When you consume carbohydrates, they are broken down into simple sugars during the digestion process, which then enter your bloodstream. However, not all carbohydrates are equal in terms of their impact on blood sugar levels. Different types of carbs have distinct effects.

The glycemic index (GI), a system developed in the early 1980s by Dr. David Jenkins, a Canadian professor, measures and ranks foods based on their influence on blood sugar levels. The glycemic index (GI) measures how different foods affect blood sugar levels compared to the absorption of 50 grams of pure glucose, which serves as the reference food with a GI value of 100.

Choosing foods with a low GI value is recommended as they are digested and absorbed slowly, leading to a gradual and moderate increase in blood sugar levels. Conversely, foods with a high GI value should be consumed in moderation as they are quickly digested and absorbed, causing a rapid rise and subsequent drop in blood sugar levels.

Factors influencing the Glycemic Index (GI) of food

Various factors contribute to the GI value of a food or meal, which are as follows:

• Sugar type - It is incorrect to assume that all sugars have a high GI. The GI can vary based on the specific sugar present, ranging from as low as 23 for fructose to as high as 105 for maltose. Consequently, the GI of a food is influenced by the particular sugar it contains.

• Starch structure - Starch, a carbohydrate, consists of two molecules known as amylose and amylopectin. Amylose is less easily digested compared to amylopectin. Foods with a higher proportion of amylose tend to have a lower GI.

• Carbohydrate refinement - The processing techniques involved in refining carbohydrates, such as grinding and rolling, disrupt the amylose and amylopectin molecules, thereby increasing the GI. Generally, highly processed foods have a higher GI.

• Nutrient composition - The inclusion of protein or fat in a meal can slow down the digestion process and contribute to reducing the glycemic response. Consequently, the presence of protein or fat in a meal can affect its GI.

• Cooking method - The way food is prepared and cooked can also impact its GI. In general, longer cooking times lead to faster digestion and absorption of sugars, resulting in a higher GI.

• Ripeness - Unripe fruits contain complex carbohydrates that break down into sugars as they ripen. Consequently, the ripeness of fruit influences its GI. For instance, an unripe banana has a GI of 30, whereas an overripe banana has a GI of 48.

Benefits of low GI food

• Reduces blood sugar - Managing blood sugar levels effectively is crucial in order to prevent and delay the onset of complications such as heart disease, stroke, and damage to the nerves and kidneys. Several studies have indicated that adopting a low glycemic index (GI) diet can help reduce blood sugar levels in individuals with diabetes. Furthermore, research has established a potential association between high GI diets and an increased risk of developing type 2 diabetes. 

• Fertility and pregnancy - Low-calorie and low-glycemic diets have been found to have potential benefits for individuals undergoing in vitro fertilisation (IVF). The study showed that this diet led to a reduction in body fat and body mass index (BMI), thereby improving pregnancy outcomes. Additionally, individuals who follow a low glycemic index (GI) diet have a lower risk of experiencing excessive foetal growth, known as macrosomia.

• Reduction in cholesterol levels - Research indicates that low GI diets can lead to a reduction in total cholesterol levels LDL (bad) cholesterol levels. Elevated LDL cholesterol is associated with an increased likelihood of heart disease and stroke.

• Reduced Cancer Risk - Certain studies propose that people who follow high GI diets are more prone to developing specific types of cancer, such as endometrial, colorectal, and breast cancer, compared to those adhering to low GI diets.

Limitations of the low GI diet

While the low GI diet offers numerous advantages, it also comes with certain drawbacks.

Firstly, relying solely on the glycemic index (GI) fails to provide a comprehensive nutritional assessment. It is crucial to consider other factors like fat, protein, sugar, and fibre content in foods, irrespective of their GI value. Furthermore, there exist numerous unhealthy low GI foods, such as a Twix bar with a GI of 44, and ice cream, which can have a GI ranging from 27 to 55 for low-fat versions.

Another limitation is that the GI measures the impact of individual foods on blood sugar levels, while most meals consist of a combination of various foods. This makes it challenging to accurately predict the GI of such mixed meals.

Lastly, the GI does not account for the quantity of carbohydrates consumed. However, the amount of carbs plays a significant role in determining their impact on blood sugar levels. This underscores the notion that relying solely on the glycemic index (GI) may not consistently serve as the most reliable indicator of blood sugar levels. It is crucial to take into account the carbohydrate content and glycemic load (GL) of a food as well.

Conclusion

A low glycemic diet offers potential benefits for weight loss and diabetes management, while also contributing to improved mood and energy levels. Typically, foods with high glycemic index (GI), such as bread, cereals, and sugary treats, tend to be avoided. On the other hand, lower GI options include dairy products, beans, and various fruits and vegetables. Incorporating a well-rounded low glycemic diet into an overall healthy eating regimen that provides essential nutrients is advisable. Seeking guidance from a nutrition professional can be helpful in planning and implementing such a diet effectively.