What Determines GI Value of Food

What Determines GI Value of Food
Why Food-Carbohydrate Has a Low, Intermediate or High GI Value
Diet & Weight ControlMy Low GI DietFood EnergyGuide to CarbsHow Carbs Digested
How Carbs Affect Blood SugarHow Carbs Affect InsulinHealth Risks of Excessive Insulin
Low Carb Weight Loss PlansGuide to Glycemic Index (GI)DetailsHow GI is Measured
What Determines GI ValueGuide to Glycemic LoadGI of MealsHow to Reduce GI of Meals
Low GI FoodsHow Much Carbohydrate Do We NeedWhich is Best: Low Carb or Low GI Diet
Health Benefits of Low GI DietsCarbs and Diet InformationHealthy Diet & Eating Advice
Special DietsRead Comments About My Weight Loss Support Forum
GI Values: Determining Factors

As we have seen (How Carbs are Digested) the speed at which carbohydrate is broken down in the intestinal tract into simple sugars and ultimately glucose, is usually dependent on the specific structure of the carb in question (meaning: how easy is it for the digestive enzymes to gain access to the carbohydrate) but can also be affected by other factors which interfere with the action of enzymes.

]]> ]]> Physical Structure

The physical characteristics of the carbohydrate is a major factor in determining its likely GI value.

  • The small particle size of finely ground flour gives digestive enzymes great surface area to attack and metabolize the bread. By comparison, stone-ground flour has a larger particle size and consequently a lower GI value.
  • A “puffed up” or “swollen” carbohydrate is more rapidly metabolized to glucose and has a higher GI value than less enlarged carbs. For example, fluffy white bread typically has a much higher GI value than denser rye breads.
  • A carbohydrate surrounded by fiber, like that in vegetables, beans, nuts and seeds, is better protected from rapid attack by digestive enzymes and has a lower GI value than other carbohydrates.
  • Very refined carbs (eg. many breakfast cereals) typically have most of their ‘natural’ fiber and other indigestible constituents removed. Result? These carbs tend to be rapidly metabolized into glucose.

Molecular Structure

Carbs with a simple molecular structure, like monosaccharides, are metabolized to glucose much more rapidly than more complex polysaccharides.


An interesting example of how a carb’s chemical structure can affect GI rating is seen in various starches. Starch comes in two forms, amylose and amylopectin. Starchy carbs typically contain a mixture of the two types, but the molecular structure of amylose is tighter and more compact, thus less easy to breakdown than amylopectin, whose structure is more extended and more vulnerable to attack from digestive enzymes. Thus, carbohydrates like beans, lentils, basmati rice with a high ratio of amylose-to-amylopectin tend to have lower GI values.

Other Factors That Influence GI Rating Cooking

Pasta has a medium-glycemic-index value of 40-50. This may be lowered by cooking it for less time (al dente). Al dente pasta resists the effect of digestive enzymes more than regular cooked pasta and so has a lower GI.

Presence of Soluble Fiber in the Gut

Soluble fiber in the stomach or small intestine inhibits interaction between carbohydrate and the digestive enzymes, whose job is to break down the carb into glucose. One reason why it’s a good idea to include a high fiber food with every meal. It helps reduce the GI value of the meal.

Presence of Acid

Acid in the stomach during digestion (eg. in the form of lemon juice) tends to slow down stomach emptying and thus the conversion of carbs to glucose.

Presence of Fat

The same applies to fat. Like acid, fat retards stomach emptying and thus glucose metabolism. This explains why certain candy bars have relatively low GI values, despite their refined nature and simple physical structures.

Presence of Sugar

A concentration of sugar in the stomach and intestine typically inhibits the effects of digestive enzymes, as it attracts water which would otherwise help in glucose metabolism.

Back to Top

Next: What Exactly is Glycemic Load?
Back to Guide to GI Diet

For the BEST Low-GI Diet, the BEST tips
and the BEST personal support forum on the ENTIRE INTERNET
see: Read About My Weight Loss Program


My System | Weight Loss Diet Program | 9 Diet Programs – Try Them All! | GI Diet | Low Carb Diet | Balanced Diet
Low Calorie Booster Diet | Cholesterol-Lowering Diet | Vegetarian Diet | Support | Weight Loss Forum
Our Weight Loss Community | Weight Management Program Information For Doctors
Weight Loss Help | Healthy Weight Advice | Health Risks of Obesity | Body Mass Index Chart | Obesity Information
Weight & Health Risks | Ideal Weight for Women | Ideal Weight for Men | Waist Circumference | Body Fat Percent
Body Fat & Health | Body Fat Calculators | Reduce Fat Belly | Obesity & Breast Cancer | What Causes Weight Gain
Hypothyroidism | Weight Loss Plateau | Healthy Cholesterol Level | How to Lower Cholesterol | Low Cholesterol Diet
Diabetes Diet | Diabetic Diet Questions | Eating Disorders | Food Cravings | Health & Weight Benefits of Exercise
Weight Loss Tips | Best Support Group | Easy Ways to Lose Weight | Lose Last 10 Pounds | Nutrition and Pregnancy
Lose Weight After Pregnancy | Weight Loss – Pregnancy | Mid-Life Weight Gain | Weight Control in Menopause
Menopause & Diet | Weight and Depression | Teen Weight Loss & Healthy Eating | Help For Overweight Children
Child Obesity | Weight Chart For Children | Weight Loss For Men | Fast Weight Loss | Raise Metabolism
Best Exercise to Burn Calories | Exercise and Calories Burned | Diet Pills | Weight Loss Drugs to Reduce Obesity
Bariatric Surgery | Gastrointestinal Surgery | Health Dangers of Bariatric Surgery | Health Dangers of Gastric Bypass
Weight Loss Programs | Articles | Weight Loss Questions | How to Reduce Weight | Weight Loss Advice
Healthy Diet Advice | Healthy Diets For Women | Reviews of Diets | Diet News | Fad Diets | Cabbage Soup Diet
Weight Watchers Diet | Low Fat Diet | Carbs and Diet | Dr Atkins Diet | South Beach Diet | Zone | Cider Vinegar Diet
Carbs Guide | Carbs & Blood Sugar | Carbs & Insulin | Carbohydrate Needs | Glycemic Index Guide | GI Diet Method
Low GI Foods | Glycemic Load | Diets For Health | Diet & Health | Diet For High Blood Pressure | Fibromyalgia Diet
Gluten-Free Diet | Irritable Bowel (IBS) Diet | Lactose-Free Diet | Best PCOS Diet | PMS Diet | Online Diet Plans
Food Digestion | Calories Index | Guide to Calorie Needs | Calorie Needs for Women | Calories & Weight Loss
Burn Calories and Lose Weight | Calories Used by Exercise | Calorie Savings | Diet Nutrition | Vegetarian Nutrition
Guide to Healthy Diet | Guide to Healthy Eating | Diet Foods | Diet Fat | Good Fat | Protein in Diet | Protein Needs
Good Protein | Good Carbs | Dietary Fiber Guide | Sodium in Diet | Dietary Sugar | Water Needs Add Your Site | Site Map
© 2000-2007 Anne Collins. All rights reserved.