Low Glycemic Index Diet: What You Need to Know

Do you suffer from problems related to metabolism? In that case, you may be interested in knowing how to plan a low glycemic index diet. We'll tell you about it in the following article.

Written and verified by el nutricionista Saúl Sánchez.

Last update: 15 August, 2023

The low glycemic index diet is suggested for those who have metabolic disorders. This meal plan can help increase insulin sensitivity, thus improving health. It helps to reduce the percentage of body fat, which helps control inflammation in the body.

It must be taken into account that metabolic diseases such as diabetes have become a very recurrent problem among the general population. This is due to the poor diet carried out in most developed countries, where the intake of ultra-processed products with simple sugars and trans fats predominates.

What is the low glycemic index diet based on?

One of the pillars of the low glycemic index diet has to do with the inclusion of foods with complex carbohydrates in the diet. A restriction of simple sugars is suggested, as these elements are capable of negatively affecting the functioning of the body. This is evidenced by research published in the journal Frontiers in Bioscience.

These products are mainly tubers, cereals, legumes, and vegetables. Fruits are also included among the foods with a low glycemic index, despite the presence of fructose inside. This is mainly due to the effect of fiber, which modulates the absorption of sugars, reducing their impact on blood glucose.

Some fruits have to be restricted or limited in the context of the low glycemic index diet. Ripe bananas, pineapple, and raisins would be good examples of them. These are considered medium glycemic index, so it’s essential to regulate their presence in the diet in order to keep blood glucose levels stable.

Also, it’ll be necessary to limit refined grains and white rice, as these foods also significantly increase blood glucose. It’s always preferable to opt for wholegrain varieties, with a greater amount of fiber that delays gastric emptying.

Are the low glycemic diet and the ketogenic diet the same?

It’s important to differentiate between the low glycemic index diet and the ketogenic diet. The first proposes a reduction in the contribution of simple sugars, including foods with complex carbohydrates in the diet. However, in the second case, we’re faced with a diet that’s very restrictive in carbohydrates in general.

Although it’s true that the ketogenic diet has been shown to generate positive effects in the prevention and treatment of many diseases, not all patients have good adherence. As for the low glycemic index diet, it’s much easier to plan, as it’s less restrictive. It’s also less likely to generate nutritional deficits.

It should be noted that the low glycemic index diet at no time generates a state of ketosis in the body, although it can promote weight loss and an increase in insulin sensitivity. Only by restricting simple sugars and refined carbohydrates can significant health improvements be achieved.

In addition, the act of consuming whole grains, legumes, and tubers ensures that fiber requirements are met, one of the weak points of the ketogenic diet. This element is essential for the maintenance of healthy microbiota, as it serves as an energy substrate. It also helps prevent and treat constipation, according to a study published in the Handbook of Experimental Pharmacology.

The benefits of a low glycemic index diet

Next, we’re going to expose the main benefits of a low glycemic diet. It’s important that it’s well designed so that these can be experienced. It should always be ensured that there are no nutritional deficits. Otherwise, complex diseases could develop in the medium term.

Improved body composition

The restriction of industrial ultra-processed foods and simple sugars leads to an improvement in the parameters associated with body composition. Weight loss is stimulated. Now, to ensure that this comes from the fat component, it’s essential to ensure that the daily protein requirements are covered. These are the nutrients that prevent muscle catabolism.

According to research published in the Annals of Nutrition & Metabolism, at least 0.8 grams of protein should be consumed per kilo of body weight in the case of sedentary people. This amount can be tripled in the case of athletes, as they have greater muscle wear that must be compensated for.

Likewise, half of the proteins in the diet must be of high biological value. These are those that come from foods of animal origin. They have all the essential amino acids and a good score for digestibility. This guarantees that there won’t be a deficit in any of the amino acids that the body isn’t able to synthesize, which could affect health.

However, the best results in terms of weight loss are obtained when resistance exercise is performed in addition to the diet. As it’s a complex carbohydrate regimen, intense physical work can be considered that activates the metabolism and promotes muscle gains.

Glycemic control

Avoiding the consumption of simple sugars improves glycemic control. There’s an increase in insulin sensitivity over time, which ensures good health at the level of the pancreas. The risk of developing type 2 diabetes is reduced, which is great news when it comes to body function.

It’s important to note that added sugars and trans fats are the elements that most favor the development of diabetes, as stated in a study published in the journal Diabetes & Metabolic Syndrome. Artificial sweeteners can also generate a similar effect, although solid evidence to confirm this in the long term is still lacking.

Another protective element is the contribution of fiber, a point that’s ensured in the context of the low glycemic index diet. This element is key to delaying gastric emptying and modulating the absorption of carbohydrates at the intestinal level, thus generating better glycemic control and avoiding the development of insulin resistance.

In any case, as in the previous case, these effects are magnified when physical exercise is carried out in parallel with the eating plan. Above all, strength work manages to generate a series of adaptations that reduce systemic inflammation and improve metabolic function. Thanks to this work, the incidence of diseases such as diabetes is reduced.

Establishing a healthier lipid profile

The low glycemic index diet also causes an improvement in the lipid profile. It’s partly conditioned by the greater presence of fiber in the diet, although the reduction in the contribution of simple sugars and trans fats is also decisive. Fiber limits the absorption of cholesterol at the intestinal level, although this isn’t the most significant data, as there’s an endogenous synthesis at the liver level that compensates for it.

What really makes a difference is the contribution of antioxidant substances through this type of diet. By prioritizing the consumption of plant foods, a large number of phytonutrients are included in the diet. These intervene by neutralizing the formation of free radicals and their subsequent accumulation in the body’s tissues.

At the same time, antioxidants are able to prevent the oxidation of LDL-type lipoproteins, which improves the lipid profile and appears to reduce cardiovascular risk. This is evidenced by a study published in The Journal of Nutrition. This effect is very important in reducing the risk of atheroma plaque formation in the blood vessels.

However, a low glycemic index diet approach doesn’t always translate into a reduction in total cholesterol. As we’ve mentioned, endogenous lipoprotein production compensates for limitations in intestinal absorption. Therefore, blood cholesterol levels have a certain genetic determination that’s difficult to modulate.

In any case, to this day, total cholesterol isn’t considered a determining marker in terms of cardiovascular health. Experts focus on small portions of lipoproteins or their level of oxidation. Also, certain parameters that offer information on inflammation can be decisive.

Increased feeling of fullness

Fiber is an element that generates satiety. This is because it delays gastric emptying, so the stomach sends signals while it’s still working and it’s not convenient for more food to be introduced. In addition, by exercising effective control over blood glucose, the risk of a drop in sugar occurs, which is something that could increase appetite through a situation of acute fatigue.

In fact, most diets that aim to promote weight loss are characterized by including a large amount of vegetables in the diet. These foods have a low energy density but a high water and fiber content. Both elements generate distension at the stomach level, which makes the body understand that there’s no need to introduce more food inside.

It must be taken into account that when ultra-processed foods are abundant in the diet, marked periods of appetite and satiety are more likely to occur, mainly dominated by fluctuations in blood glucose. This is one of the causes of the aforementioned insulin resistance, one of the preludes to type 2 diabetes.

Of course, for the low glycemic index diet to have a greater effect in terms of appetite control, it’s essential to ensure an optimal intake of fluids. A part of the fiber has the ability to swell in the presence of water. In addition, the own intake of a glass of this liquid before main meals has been shown to increase the feeling of fullness later.

Approaching a low glycemic index diet

When planning a low-glycemic diet, the first thing to do is calculate the calories you need on a daily basis. For this, different approaches can be made through trial and error. It’s also possible to apply a formula that allows calculating energy expenditure at rest, such as the Harris-Benedict equation.

It’s then multiplied by the activity factor to know the daily energy expenditure, once physical exercise has been included. In this way, you have an estimate of the calories you need. Taking into account that, under normal conditions, you’ll need to guarantee the balance at the dietary level. Optimally, the calories ingested are equal to those consumed.

The next thing is to ensure the intake of protein. For this, the degree of physical activity will have to be determined. The more you exercise, the more protein per kilo of weight per day will be necessary. Remember that it’s important that at least half of the protein you consume should come from foods of animal origin. This ensures that essential amino acid requirements are met.

Once both points have been overcome, it’s time to include carbohydrate foods in the diet. As we’ve mentioned, it’s essential to prioritize those with a low glycemic index. Just the same, we’ll leave you examples of the 3 types of foods with sugar that can be found so that you’re clear which belongs to each group.

• Low glycemic index foods: Green vegetables, fruits, carrots, beans, legumes, tubers, whole grains, oats, brown rice, and pseudo-cereals.
• Medium glycemic index foods: Sweet corn, bananas, pineapple, raisins, breakfast cereals with no added sugar, and multigrain bread.
• High glycemic index foods: White rice, white bread, pasta, ultra-processed, and sweets.

Bread consumption

Bread is one of the foods that generate the most debate among nutrition experts. White bread produced from refined wheat flour is a rather poor quality product. However, it’s possible to find some varieties made with sourdough, wholegrain flour, and seeds that could be introduced in a specific way in the diet.

These varieties have higher proportions of resistant starch, a substance that generates an effect similar to fiber for all purposes. It’s essential to ensure the good health of the microbiota, as it promotes the growth of bacteria that inhabit the digestive tract.

However, it’s not a good idea to consume bread as an accompaniment to meals, nor within the framework of the low glycemic index diet. When introducing this product into the diet, it should be the main source of carbohydrates on the plate. Otherwise, their contribution would be excessive.

How many carbohydrates to introduce into the diet

The amount of carbohydrates present in the diet will depend on the lifestyle of the person. If they exercise, up to 45% of the total calories in the diet may need to come from this nutrient. Keep in mind that each gram of sugar has 4 calories.

When we talk about sedentary people, ensuring that 25% of daily energy comes from carbohydrates may be enough. This approach can even be beneficial for metabolic health in the medium and long term.

Of course, it’s important to always avoid simple sugars and those foods with a high glycemic index. Otherwise, diseases could be promoted over time, as is the case with type 2 diabetes. The important thing is that the presence of fiber in dishes is always ensured, taking into account that in main meals, carbohydrates will always or almost always be included.

The contribution of fats

Ensuring the presence of quality fats in the context of a low glycemic diet is another of the determining points. The amount of them will depend on the previously established carbohydrate needs. Normally, lipids never account for less than 25% of daily energy.

It’s essential that, on a daily basis, unsaturated fatty acids are included, especially those of the omega-3 series. These have anti-inflammatory capabilities that can prevent the development of complex diseases, such as cardiovascular and metabolic diseases.

Likewise, trans-type fatty acids should be avoided, as they could cause an increase in insulin resistance. They’re mainly found in industrial ultra-processed foods and those foods with fats that have been subjected to aggressive thermal processes, such as frying or cooking on the grill.

The importance of avoiding soft drinks

Although we haven’t placed them in any of the previous groups, soft drinks are among the products with a high glycemic index. They’re one of the worst elements to introduce into the diet. When sugar comes in liquid form and doesn’t contain fiber, the sugars they contain pass into the blood very quickly, which raises blood glucose.

The regular intake of sugary soft drinks alters inflammatory markers and other parameters related to health, such as blood pressure. They’re associated with an increased risk of developing metabolic diseases and other complex diseases, so it’s best to eliminate them from the diet.

Those that don’t have added sugars aren’t a good option either, as they contain artificial sweeteners. These compounds generate alterations in the body that can condition health in the medium term. In many cases, it’s unknown for sure what the impact on the functioning of the physiology is.

When it comes to ensuring a good state of hydration, the best tool is water. On some occasions, whole milk can be consumed. However, juices should also be avoided, as they generate an effect similar to soft drinks. Shakes and smoothies aren’t healthy options either.

Of course, the restriction of alcohol is a basic point in this and in any other diet. This substance is toxic regardless of the dose consumed. It affects blood glucose and hormonal balance, increasing the incidence of complex diseases in the medium term.

Use the low glycemic index diet to improve metabolic health

From a low glycemic index diet, metabolic health can be improved in the medium term. The restriction of simple sugars and their replacement by foods with complex carbohydrates is quite positive for the body. However, it will also be decisive to increase the consumption of vegetables and high-quality proteins.

It should be noted that for the effects to be noticeable, you need to complement a good diet with other healthy habits. Among them, the practice of physical exercise on a regular basis stands out, prioritizing strength work above all. Increasing the percentage of lean body mass will contribute to effective glycemic control.

Finally, it’s essential to sleep well. During sleep, the repair processes of the human body take place. The production of certain hormones that help to ensure balance in the internal environment is also increased. It’s important to ensure 7 to 8 hours of quality sleep each night, with a good proportion of deep sleep.