Low Glycemic Diet: Definition, Downsides, and Benefits

by Victoria Mazmanyan | Last updated on August 24, 2023

Medically reviewed by Astghik Grigoryan

The low glycemic diet is an eating plan that involves choosing foods with low glycemic index values. This diet is said to help with weight loss, blood glucose control, acne, and more. In this article, we will take a closer look at what this diet entails, its benefits and downsides, and what science has to say about it.

What is the Glycemic Index (GI)?

The glycemic index is a tool to measure how much a given food affects blood glucose levels after consumption. It does not provide us with information about the number of carbohydrates contained in the food but rather their quality.

Consuming foods with high GI values leads to a rapid increase in blood glucose, followed by a rapid increase in insulin, while low GI foods lead to a gradual increase in glucose and insulin.

The glycemic index value of foods falls within the range of 0 to 100. Pure glucose has a GI value of 100, while foods with no carbohydrates are considered to have a GI value of 0.

Based on these values, the GI is classified into three groups:

Low: a GI value below or equal to 55
Medium: a GI value from 56 to 69
High: a GI value above or equal to 70

You can learn more about the definition of the glycemic index and what it is on our page.

What Should You Eat on a Low-Glycemic Diet?

Low glycemic index foods include various food groups, such as meat and dairy products, fruits and vegetables, legumes, and nuts.

Here’s a list of some low glycemic index foods you can choose from:

Meat: beef, pork, chicken, turkey, rabbit, duck, fish, crab, lobster
Dairy: cheese, butter, milk, plain yogurt
Fruits: cherry, apple, pear, apricot, grapefruit, strawberry, avocado, passion fruit, guava, dried fruits
Vegetables: tomato, cucumber, eggplant, carrot, cabbage, lettuce
Nuts: almond, walnut, pecan, peanut, cashew, pistachio
Legumes: green bean, black turtle bean, kidney bean, lentil, soybean
Grains: barley, rye
Oils: vegetable oil, coconut oil, sunflower oil
Other: eggs, hummus, agave nectar, peanut butter, tofu, soy milk, dark chocolate, spices and herbs

Based on this list, we can see that the low glycemic diet has similarities with the Mediterranean diet. The main difference between these two diets is the presence of meat and dairy on a low glycemic diet. In comparison, the Mediterranean diet uses more grains.

Most meats contain no carbohydrates and, therefore, are considered to have a glycemic index of 0. Processed meat is more likely to have a higher GI.

Except for beer, alcoholic beverages, such as wine, whiskey, vodka, and rum, also tend to have a low glycemic index.

Honey or maple syrup can be the choice of sweetener during this diet, as they have medium GI values, as opposed to the high GI values of sugar and corn syrup. However, it is advised to limit foods with glycemic index values that fall in the medium category.

If you didn’t find the food you’re looking for, you could look at our Glycemic Index Chart for a complete list of the glycemic index values of over 350 foods.

What Shouldn’t You Eat on a Low-Glycemic Diet?

Here is a list of some foods to avoid on this diet:

Fruits: jackfruit, pomelo, pineapple
Vegetables: starchy vegetables (potato, cassava, parsnip)
Grains: rice, amaranth
Bread: white bread, bagel, pretzel, waffle
Legumes: broad (fava) bean, yardlong (asparagus) bean
Other: coconut milk, corn syrup, instant oats, beer

The diet recommends avoiding potatoes and potato products, such as mashed potatoes, baked potatoes, and french fries.

As seen above, the same food groups can include both low and high-glycemic index foods.

It is important to keep in mind that the exact type of food and cooking method can significantly alter the GI values. For example, instant oat porridge has a high average GI value of 82, while the GI of porridge made from rolled oats is 58.

In general, processed foods tend to have higher glycemic index values and are not favorable for this diet.

Health Impact

Diabetes and Cardiovascular Disease

The latest research shows that a low glycemic index diet is preferred over a high glycemic index or other diets for the control of body mass, body mass index, fasting blood glucose, and glycated hemoglobin levels in patients with one of four common metabolic diseases: obesity, metabolic syndrome, diabetes, and cardiovascular disease (1).

In the long term, a low glycemic diet has been associated with weight loss and reduced fasting blood glucose levels (1, 2). A low glycemic diet can also help improve blood pressure, blood lipid levels, and inflammation (3, 4).

Meanwhile, a diet rich in high glycemic index foods has been linked to an increased risk of cardiovascular disease; metabolic syndrome is also linked with hypertension; this can result in left ventricular hypertrophy, which is clinically significant because it is linked to an increased incidence of heart failure, ventricular arrhythmias, and death following myocardial infarction (5).

Acne

Numerous studies suggested that a high glycemic index diet exacerbates acne severity, while a low glycemic diet may improve acne by playing a role in its pathogenesis (6, 7, 8, 9, 10).

For people with acne, a low glycemic load diet may be the preferred choice over a low glycemic index diet to manage the intake of carbohydrate content better.

However, in Western populations, dairy intake has also been found to promote acne (6). Therefore, a limitation of dairy may need to be added to the standard low glycemic diet.

Epilepsy

In recent years, the low glycemic diet has been at the center of attention as a potential choice of complementary treatment in epilepsy.

The ketogenic diet has been known to impact epilepsy positively; however, it has been deemed as an inconvenient diet to maintain due to the strict carbohydrate limitations. The low glycemic index treatment was developed as an alternative to the ketogenic treatment.

One study demonstrated a combination of a low glycaemic diet and aerobic exercise to improve seizure frequency, depression levels, and quality of life in children with epilepsy (11).

Another study showed that in children with drug-resistant epilepsy, a low glycemic diet along with antiseizure medications is more effective than the medications alone (12).

In short, a low glycemic index treatment may help reduce seizure frequency and the need for antiseizure medication (13, 14).

Polycystic Ovarian Syndrome (PCOS)

Researchers have found that low glycemic diets may prevent polycystic ovarian syndrome, reduce its symptoms, and improve its biochemical aspects (15).

Women with PCOS who are overweight but not morbidly obese may benefit from a low glycemic diet over a conventional healthy diet for managing insulin resistance, cardiovascular risk, and irregular menstrual patterns (16).

Downsides and Shortcomings

Despite its several benefits, the low glycemic diet also has some disadvantages that should be considered.

Unhealthy foods can have low GIs.

A diet based on the glycemic index takes into consideration only carbohydrates, but not fats, protein, and other nutrients. Thus, some unhealthy foods can fit into the low glycemic diet:

margarine (GI of 0),
processed meats,
hot dog (GI of 28),
falafel (GI of 33),
burrito (GI of 37),
chocolate cake (GI of 41),
chocolate brownie (GI of 42), and more.

The same food can have different GI values.

The food's glycemic index value can sometimes differ greatly depending on various factors. Some of these factors include the variety, cooking method, the ripeness of the fruit, the nutrient composition of the meal, and the calculation method.

For example, most raw pineapples have a moderate GI value of around 66; however, one study found the GI of pineapple to be 19 by using an alternative approach, while another study demonstrated the GI of bananas from Nigeria to be 95 (17, 18).

Calculating GI values of mixed meals can be difficult.

The glycemic index of mixed meals is calculated by using a formula, not measured. However, some experts find this method to lead to an overestimation of GI values, as different nutrients, such as fat and protein, can alter the GI of the meal (19).

On our page, you can learn more about what affects the glycemic index and response.

At the same time, other studies have found that by considering these effects, the calculated GI value of the meal can be accurately adjusted (20).

Nonetheless, difficulty calculating the GIs of mixed meals somewhat complicates following a low glycemic index diet.

The GI does not consider serving sizes.

The glycemic index gives us information about the carbohydrate’s quality but not quantity. The GI is a set value for each food, regardless of the amount consumed. In other words, the GI does not take into account differing portions of the food.

In order to solve this issue, another value was created - the glycemic load (GL). The glycemic load represents the GI value of the food along with the number of carbohydrates per serving size.

The best example of this drawback of the GI is watermelon. Watermelon has a high GI value of 76; however, the GL of a one-cup serving of diced watermelon is only 8 due to its high water content.

It is apparent that a low glycemic index diet will benefit from incorporating the glycemic load as well.

References

Author name: Victoria Mazmanyan

Education: General Medicine at YSMU

Last updated: August 24, 2023

Medically reviewed by Astghik Grigoryan