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Glycemic Index Diet (Low GI Diet)

What is it?

Glycemic Index (GI) diet plans are centered around the glycemic index, which is a scientific ranking that classifies foods based on how quickly they raise blood sugar levels. Initially developed as a tool to help diabetics manage their blood sugar, the glycemic index is now the basis for multiple mainstream weight loss plans.

High-GI foods trigger a rise in blood sugar and release insulin, which is thought to promote fat storage, intensify hunger, and subsequently lead to weight gain. The premise of GI diets is that by avoiding foods that have a high-GI score, your appetite will decrease, and you will subsequently lose weight.

The glycemic index runs from 0 to 100 and uses glucose, which has a GI score of 100, as a reference point. The effect foods have on blood sugar levels are compared with this, and then given a GI value of their own.

The majority of GI diet plans suggest eating low-GI foods such as many vegetables, and whole grains. Foods that are considered to have a high-GI rating (greater than 70) are to be avoided.

Low-GI foods include:

  • oats
  • whole grains
  • brown rice
  • cabbage
  • mushrooms
  • tomatoes
  • onions
  • apples
  • oranges
  • strawberries
  • cashew nuts
  • peanuts

The Promise

Low-GI diets promise that you won't go hungry while dropping the pounds. Plus, sticking to low-GI foods could help to lower your risk for stroke and diabetes. Research also suggests that a low-GI diet could improve levels of good cholesterol and reduce the risk of heart disease. Many GI diets estimate that on average you will lose between one to two pounds per week, and will maintain a slow, steady weight loss for as long as you stay on the low-GI meal plan.

Pros & Cons

Low-GI diets promote the eating of healthy food and normally offer an easy-to-follow format on what you can and can't eat. Many GI diets also provide a wide range of recipes and healthy meal plans. However, eating foods with a low-GI count as a method of weight loss isn't scientifically proven and can be confusing. There is a wide range of GI scores based on a variety of factors that can affect foods, such as ripeness and cooking times. For example, the riper a banana, the higher its GI value is going to be. Plus, GI index scores only pertain to the effect foods have on blood sugar levels when they are eaten on their own, and not when they are consumed with other foods. This is a fundamental problem that many nutritionists and skeptics have with GI diets. It's not the GI score of individual foods that should be considered; it's the GI score of an entire meal that matters. Research has also shown that the GI response of foods can vary tremendously from person to person, and can even change within the same person from day to day. These factors all make it very difficult to gauge whether or not the diet is actually being followed correctly.

Healthline Says

GI diet plans are the center of very popular and successful weight loss programs, including The South Beach Diet and The Zone. Low-GI foods are often healthy, including leafy vegetables, lots of fiber, and whole grains. However, some foods with a low-GI value are also loaded with salt, fat, and very little nutrients. Likewise, foods such as dates, broad beans, and baked potatoes— which are full of nutrients and should all be considered as part of a healthy diet—have high GI values and are thus included in the category of "foods to be avoided" for those on a GI diet. It's important to be aware of the nutritious value of foods, not just their GI score.

While there are many who are convinced that low-GI foods will encourage weight loss, it's not scientifically proven. Research does show, however, that many low-GI foods could help to prevent heart disease, stroke, and diabetes.

Low-GI diet plans may have some merit. As long as you use common sense and select healthy whole grains, lean protein, and good fats, a GI diet could be the right approach for a weight loss strategy for you. As with any healthy weight loss program, it's important to be aware of portion sizes, and include regular physical exercise.

Content licensed from:

Written by: Tracy Stickler
Medically reviewed : Tara Gidus, MS, RD, CSSD, LD/N

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.
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