The human body uses carbohydrates as it's main energy source. However, not all carbohydrates have the same effect on the body; some carbohydrate foods are broken down rapidly when they reach the intestine and cause blood glucose levels to rise quickly. These foods rank high on the glycemic index. Other carbohydrate foods release sugar into the bloodstream more slowly, and these foods are low GI foods. Low GI foods are considered more suitable for people with diabetes, or those attempting to lose weight, as they do not cause large spikes in insulin levels.
Fruits
In general, fruits have a medium or low ranking on the glycemic index. Common fruits such as apples, oranges, grapes and pears rank as a medium GI fruit; low GI choices include strawberries, plums, cherries and grapefruits. High glycemic index fruits are bananas, mangos, pineapples and watermelons. Dates and raisins have a very high GI ranking. As an average rule of the thumb, sweeter fruits rank higher on the glycemic index, according to diabetes writer David Mendosa's website.
Vegetables
If you want to lose weight but you eat a lot of high GI foods, you may find that soon after eating you feel hungry again, or that you are craving sweet sugary foods such as candy. This is because after consuming the high GI food, glucose will be released into your blood very quickly.
When glucose is present in the bloodstream, the pancreas produces insulin to help the glucose get to the cells that can use it for energy. If you eat an abundance of high GI foods, the body is likely to produce too much insulin, which can cause problems such as high blood pressure, insulin resistance and an increased appetite.
Therefore, vegetables are excellent food sources if you want to avoid high glycemic foods, as they tend to be very low on the GI index, and release glucose into the bloodstream at a slow steady trickle, leaving you feeling fuller for longer. Corn on the cob and beets are among the few exceptions, as they have a high glycemic index, according to "The G.I. Diet" by Rick Gallop.
Starches
Starchy foods tend to be high GI foods, and should be avoided by those suffering from diabetes. If you are attempting to follow a low GI diet, preferred sources of starchy foods are rye breads, corn tortillas or wholemeal pasta. French style bread, popcorn, and potatoes are extremely high on the GI index, and cause blood sugar levels to rise rapidly, according to David Mendosa.
Proteins
The Glycemic Index refers to the carbohydrates in food sources, and as protein sources such as meat, poultry, fish and eggs have a very low carbohydrate content, if any at all, the glycemic index is not relevant for these foods. However, if you are eating a protein source fried in breadcrumbs, or covered in a source containing sugar, it will contain carbohydrates and will therefore have an effect on your blood sugar levels, which should be taken into consideration if you are switching to a low GI diet.
Fats
Foods high in fats such as cheese, butter and bacon are low GI foods, due to their low carbohydrate content. However, it is preferable to moderate your intake of fat from these foods, and to eat dietary fat in the form of monounsaturated fats, which can be found in olive oils, avocados, nuts and seeds, says the Nutrition Data website.
References
- Mendosa: The Glycemic Index
- Mendosa: Glycemic Index Lists
- Whole Foods: Glycemic Index
- Nutrition Data: Monounsaturated Fat
- "The G.I. Diet"; Rick Gallop; 2010
