Carbohydrates are the primary source of energy in the body. Once consumed, carbohydrates are digested into simple molecules of glucose, and glucose is used to generate energy for cells, tissues and organs. The brain and red blood cells need glucose as an energy source, since they do not normally use fat or protein for this purpose. However, while carbohydrates are critical to bodily functions, eating too much of the nutrient can add inches to the waistline, because excess carbohydrates are converted to body fat.
Types of Carbohydrates
There are two main types of carbohydrates: simple and complex. Simple carbohydrates are also called simple sugars; they are broken down quickly by the body to be used as energy. Simple carbohydrates are found naturally in foods such as fruits, milk and milk products. They are also found in processed and refined sugars such as candy, table sugar, syrups and soft drinks.
Complex carbohydrates include dietary starches and fiber. Compared to simple carbohydrates, complex carbohydrates take a longer time to be broken down. Whole grains such as wheat bran or oatmeal are examples of high-fiber, complex carbohydrates.
According to the book “Nutrition: Concepts and Controversy,” all consumed carbohydrates are broken down and are converted to glucose. As glucose enters the blood, the concentration of sugar in the blood rises. In response, the pancreas releases insulin to remove the surplus of sugar in the bloodstream and blood sugar is lowered as a result. Insulin also causes excessive glucose molecules to be linked together and be stored as glycogen in the liver and muscles. When glucose is needed by the body, glycogen is broken down and glucose becomes available. However, because the body can only store a limited amount of glycogen, the excess glucose is stored as body fat.
Insulin and Fat
The insulin that is released as a result of the increase in blood sugar is also responsible for body fat storage. According to a study published in the January 2007 issue of “Kobe Journal of Medical Sciences,” insulin is an anabolic hormone, which is a type of hormone that promotes synthesis and storage. Insulin promotes the synthesis of glycogen, which is a storage form of glucose molecules. However, insulin also promotes the synthesis of triglycerides, which is a storage form of fats. Furthermore, insulin prevents the body from breaking down fat, because it inhibits the production of fat-burning enzymes.
Simple carbohydrates are used immediately for energy should the body require it. Therefore, when the body burns simple sugars for energy instead of fat, it means that the body burns less fat. Simple carbohydrates also lead to a spike of insulin, which will promote the storage of extra sugars as body fat. Complex carbohydrates, on the other hand, cause a slower and more gradual rise in insulin because they break down more slowly. They are therefore less likely to turn into fat.
- Medline Plus: Carbohydrates
- European Food Information Council: Carbohydrates
- Centers for Disease Control and Prevention: Carbohydrates
- Nutrition: Concepts and Controversy; Frances Sienkiewicz Sizer et al.
- Kobe Journal of Medical Sciences: Insulin Efficiently Stores Triglycerides in Adipocytes by Inhibiting Lipolysis and Repressing PGC 1-alpha Induction
- Joslin's Diabetes Mellitus; C. Ronald Kahn et al.
- Nutrition Complete: Carbs: The Truth, the Whole Truth and Nothing But the Truth!