Digestion of Carbohydrates - Glucose Metabolism
How Carbs Are Digested in Stomach, Small Intestine

Carbs in Food
Glycemic Index GI of Carbs
Glycemic Load of Carbs
GI Diet - Low GI Diet

Information About Carbs | Carbohydrates Guide | Low Carb Diets

Digestion of Carbohydrates

What Are Carbohydrates? - Complex Carbohydrates - Monosaccharides
Disaccharides - Oligosaccharides - Polysaccharides - Simple Carbohydrates - Starch - Sugars
Dietary Fiber - Types of Dietary Fiber - Best Sources of Dietary Fiber - Benefits of Dietary Fiber
Daily Fiber Needs - Fiber & Weight Loss - Fiber & Low Carb Diets

Simple carbs, being sugars (glucose), are absorbed into the bloodstream very quickly. The exception is fruit sugar (fructose) which needs to be converted into glucose first.

Complex carbs (especially low glycemic index complex carbs) many of which are starchy carbohydrates, need more time to be digested.

The Digestion Process

Digestion of Starches

The process begins in the mouth when an enzyme in saliva (amylase) begins to break down starchy carbohydrates.

After swallowing, the starchy carbs reach the stomach where hydrochloric acid combines with them and acts on the protein in the food. The stomach also acts as a reservoir for food, squirting out small amounts into the intestines at intervals.

In the small intestine (where most carb-digestion occurs) the starch is processed by the enzyme amylase and converted into maltose and sucrose.

The maltose and sucrose are then absorbed into the lining cells of the intestine and are further simplified, being converted into glucose.

Digestion of Sugars

Simple carbohydrates, or sugars, (eg. table sugar) are digested by an enzyme in the lining of the small intestine. Examples: Table sugar is broken down into glucose and fructose, each of which is then absorbed from the intestinal cavity into the blood. Milk contains another type of sugar, lactose, which is broken down by an enzyme called lactase, also found in the intestinal lining. See also Carb Blockers

When Glucose Enters the Bloodstream

Once the starchy or sugary carbs are digested and converted to glucose, the glucose then enters the bloodstream and the level of blood-glucose rises. This induces the pancreas to secrete insulin into the blood which "mops up" the glucose and helps convert it into the storage-type of carbohydrate, called glycogen, which is deposited in the liver and in the muscles.

When the liver and muscle glycogen stores are full, any extra glucose is converted into fat. This adds to fat stores, but to a lesser extent than fat released from fatty foods.

The liver glycogen helps to keep blood-sugar levels in the normal range. If blood sugar falls, glycogen is converted into glucose which enters the blood. If blood sugar rises (say) after a meal, insulin is again released from the pancreas which converts the glucose into glycogen. And so on.


The human body typically packs about 400 grams (14 ounces) of glycogen into liver and muscle cells. If you add up all the glucose stored in glycogen, plus the small amount of glucose in the bloodstream, it equals about 1800 calories of energy.

Digestion of Nutrients in Starches or Sugars

Other nutrients in carbs, like vitamins and minerals, are dissolved in the small intestine by the juices from the pancreas, liver, and intestine, and then absorbed through the intestinal walls. Waste or indigestible products, including dietary fiber, move into the colon. They usually remain in the colon for a day or two until expelled by a bowel movement.

Carbohydrates Definition
Carbohydrates Information
Complex Carbs Guide
Simple Carbs Guide
Starch/Starchy Carbohydrates
Sugars Carbohydrates
Carb Counting Guide
Facts About Carbohydrates
Diabetes, Carbs and Diet

Fiber in Diet
Dietary Fiber
Types of Fiber
Best Sources of Fiber
Benefits of Fiber
Daily Fiber Needs

Nutrition & Carbohydrate
Nutrition in Carbs
Minerals in Carbohydrates
Vitamins in Carbohydrates
Phytochemicals in Carbs

Carbs and Glycemic Index
Digestion of Carbs
Blood Glucose Levels
Glucose into Energy
What is Glycogen?
How is GI Measured?
What Affects Glycemic Value?
Glycemic Index Food Chart
Glycemic Index Food Pyramid
Glycemic Value of a Meal
GI Values in Carbohydrates
GI Value For Beans
GI Value For Bread
GI Value For Cereal
GI Value For Dairy Food
GI Value For Drinks
GI Value For Fruit
GI Value For Meat/Fish
GI Value For Nuts
GI Value For Snacks
GI Value For Starchy Carbs
GI Value For Sugar
GI Value For Vegetables
GI Value For Whole Grains

Carbohydrate in Foods
Atkins Diet Foods
Bagels
Beans/Legumes
Beer
Bread
Cereal
Cake
Candy/Chocolate
Chips
Cookies/Biscuits
Crackers
Donut
Dressings
Energy Bars
Flour/Baking Foods
Fruit
Grains
Ice Cream
Milk, Cream,Yogurt
Muffins
Noodles
Nuts/Seeds
Pancakes/Waffles

Carbs in Food cont/
Pasta
Pies
Pizza
Popcorn
Potatoes
Pretzels
Rice
Sauces
Soda
Soup
Soy Food
Sugars
Syrups
Vegetables
Zone Diet Foods

Diet Recipes
GI Diet Recipes
Low Carb Recipes

Carb-Controlled Diets
Atkins Diet
South Beach Diet
Zone Diet
Low Carb Dieting
Benefits of Low Carb Diets
Low Carb Diets Health Risks
Ketosis - High Ketones in Blood
Gluconeogenesis Guide
Free Low Carb Diet Advice
Low Carb Weight Loss Diet

Diabetes, Insulin, Obesity
Diabetes Information
Hyperglycemia - High Blood Glucose
Hypoglycemia - Low Blood Glucose
Obesity Information
Diabesity, Diabetes and Obesity
Insulin Information
Insulin and Obesity
Types of Insulin
Hyperinsulimia - High Insulin Levels
Insulin Resistance Syndrome


Carbs-Information.com provides general information about different types of carbohydrate, like monosaccharides, disaccharides, oligosaccharides, polysaccharides, as well as nutritional value of carbohydrates, carb-content of foods, plus details of GI values of all food groups, plus advice about diabetes, impaired glucose tolerance and insulin resistance. But no information is intended as a substitute for medical advice. Copyright 2003-2018.