You need to consume more whole grains and fewer refined carbohydrates to reduce belly fat. Refined carbohydrates have a high glycemic index (GI). The glycemic index is a scale that ranks foods based on how fast and how high they can raise your blood sugar.
The lower a food ranks on the GI scale, the less of a rise in blood sugar it creates. A food ranking high on the GI scale causes a rapid spike in blood sugar.
When your blood sugar rises quickly, you experience an increased release of insulin into the bloodstream. And because insulin can store more abdominal fat, this news is bad for your belly. So choosing carbohydrates that rank lower on the GI scale helps to limit the blood sugar and insulin response, therefore giving you an added boost in the fight against belly fat.
How the GI of a food is calculated
Carbohydrates are found in vegetables, fruits, starches, and dairy products like milk and yogurt. Any food that contains a source of carbohydrate can have a GI associated with it. In general, refined carbohydrates (processed starches, such as white bread, and foods high in added sugar, such as candy) tend to have a higher GI.
The most recent way devised to determine a food’s GI has been to use white bread as a standard for comparison. White bread was given a GI value of 100. The GI of other foods is then calculated based on how quickly blood sugar rises after consumption of the food in comparison to the white bread standard.
Foods with a GI greater than 100 raise blood sugar faster and higher than white bread, whereas foods with a GI less than 100 raise blood sugar slower and lower than this bread.
A GI value greater than 70 is considered to be a relatively high GI and may elevate insulin levels, working against your efforts to lose belly fat. Think of GI as a tool and not a rule. Even though consuming high-GI foods may make it more difficult to achieve your flat belly, you have to remember that GI is affected by more than just food itself.
It can be elevated or lowered by what that food is eaten with and how much of the food is consumed. So if you do choose to have a high-GI food, try eating it at a meal that also contains lean protein, healthy fats, and high-fiber, low-GI foods. Doing so can minimize the high-GI food’s impact on blood sugar and insulin.
Look for low-GI foods
The following lists the GI index categories of many common foods. The categories are as follows:
GI ranking of 55 or less = Low-GI food
GI ranking of 56–69 = Medium-GI food
GI ranking of 70 or more = High-GI food
| Food | GI Index Category | Food | GI Index Category |
|---|---|---|---|
| Apples | Low | Milk, fat-free or low-fat | Low |
| Asparagus | Low | Oatmeal | Medium |
| Baked russet potatoes | High | Pasta, white | Medium |
| Bananas | Low | Pasta, whole-grain | Low |
| Barley | Low | Peas | Low |
| Black beans | Low | Peppers, all | Low |
| Bran flake cereal | Medium | Pizza, white flour dough | High |
| Broccoli | Low | Popcorn | Medium |
| Brown rice | Low | Pretzels, white flour | High |
| Carrots | Low | Raisins | Medium |
| Cherries | Low | Rice cakes, white rice | High |
| Chickpeas | Low | Sweet potatoes | Medium |
| Corn | Medium | Tomatoes | Low |
| Corn flake cereal | High | Waffle, white flour | High |
| Cucumbers | Low | Watermelon | High |
| Donuts | High | White flour bread | High |
| Grapefruit | Low | White rice | Medium |
| Grapes | Low | Whole-wheat bread | Low |
| Kidney beans | Low | Yogurt | Low |
| Lettuce, all varieties | Low |
Proteins and fats aren’t listed in the table, because these are all low-GI foods (unless additional ingredients like breading have been added).