The glycemic index of food: basing the diet on this concept helps us lose weight?

Surely you have heard about the glycemic index , a parameter that tells us about the quality of what we eat and the effect of a food on our body. Today we tell you what you need to know about this index and if your knowledge helps when losing weight or is just a myth .

What is the glycemic index

The glycemic index is a value that is assigned to foods to estimate their response in our body. Specifically, the glycemic index (GI) represents the glycemic response of a food or preparation , that is, it indicates the speed at which the sugar of what we eat, converted into glucose, reaches our bloodstream.

The glucose is taken as a reference for a high glycemic index, which has a glycemic index of 100, and all those close to this value are foods that rapidly raise our blood glucose, while those with a low glycemic index are digested more slowly, producing a less accentuated curve in our blood glucose and raising it a long time after consumption.

Thus, there are glycemic index tables that include high GI foods: between 70 and 100, medium GI: between 56 and 69 and low GI: between 0 and 55 . Said tables are elaborated considering the amount of hydrates of the food and its speed of absorption, however, they have their limitations .

How can we meet him?

There are international tables of glycemic index from which we can obtain the value assigned to different foods. The last ones published are from the year 2008 and they show us the IG of 62 common foods having previously analyzed tables and studies with data of more than 2400 foods.

In many cases, the cooking method of the evaluated foods is detailed, since the processing of the food including the cooking can affect the glycemic response of the same as indicated by a study carried out in Jamaica .

In general, legumes, fruits and vegetables and dairy products are low glycemic index foods, while breakfast cereals, bread and rice, can be placed under a category of high, medium or low GI depending on whether it is whole grain or integral, of bread or white rice and of the ways of cooking them.

In all the tables of glycemic index the egg or the meats of any type are not included , because as we have said, this value is extracted taking into account the amount of hydrates of the foods and so much fish, birds and red meat as eggs do not have this nutrient in its composition.

What science tells us about the glycemic index of food and weight loss

The glycemic index was long mentioned in diets to lose weight , and although its knowledge can have great influence in the prevention and control of different diseases , today we know that its usefulness is more limited than we thought .

Researchers from Australia have observed the usefulness of the IG to control diabetes, weight gain, blood lipids and many other factors that speak of metabolic health, showing that this parameter can be valuable in the approach of overweight and obesity. However, another small study published in The Journal of Nutrition concluded that reducing GI in a diet does not offer additional benefits to energy restriction when promoting weight loss in obese people. That is, it is the same if we have low or high GI foods at the time of weight loss.

The lack of consensus about the utility of the IG to lose weight is due to its variations due to multiple factors that make it a parameter that although it guides us, it is not definitive at all.

The multiple factors that affect the IG

We already said that to create the GI tables we take into account the proportion of carbohydrates in cooked foods in different ways, so it is clear that the carrot does not have the same effect on our glucose if we consume it raw and whole than if we ingest it grated and raw or cooked and pureed.

Beyond the cooking and processing of a food that affects the GI by reducing its fiber or facilitating its digestion, this value can vary external factors such as other foods consumed.

The combination of foods can affect the glycemic response of a food only and since we do not eat many foods in isolation but we include them in more complex dishes, with other ingredients, the IG loses noticeably utility, since it is very difficult to know the IG of a stew with meats, various vegetables and legumes although we know the GI of each food separately.

As if that were not enough, as the IG depends on the process of digestion and absorption of the hydrates of a food (or several), it can vary from one person to another as demonstrated by a study published in the journal Cell something that reminds us of the great limitations of the IG at the moment of weight loss.

The IG can serve, but never in isolation

While GI has many limitations that can lead our diet when we lose weight, we should know that there is evidence of the multiple risks of consuming high GI foods such as obesity, cardiovascular problems, infertility and others that the School of Harvard Public Health , while low GI foods are associated with less inflammation and better metabolic health as concluded by research published in 2014 .

Therefore, the IG can be taken into account when losing weight and can be of great help to guide us towards a better quality diet that protects health, but should never be considered in isolation. That is, we should not only decide on the basis of GI , but considering that other foods also influence and that for example an active person can better receive high GI foods than a sedentary or that those with diabetes would need even more low GI foods than who do not suffer from this disease.

If in addition to the IG we consider fats, proteins, fiber, physical activity level, needs and other particularities of each one as well as the dishes and foods that we eat, the use of this parameter can be useful, while deciding only on the basis of GI can lead to erroneous decisions at the moment of losing weight, taking care of health .