Carbohydrates are broken down during digestion into their simplest form known as glucose, which is also called blood sugar. Your body utilizes glucose right away, or stores it for later use. Glucose is the primary energy source for all cells in your body. Having low glucose levels from inadequate carbohydrate intake causes several symptoms in your body.
Types of Carbohydrates
There are two general groups of carbohydrates that are broken down into glucose for fuel. Simple carbohydrates, such as fruit or milk sugar, or fructose and lactose, are short carbohydrate strands that are broken down into glucose and absorbed rather quickly. Complex carbohydrates, such as starch from whole grains, are a longer, more complex chains and take longer for your body to digest. Fiber is a type of complex carb, but it is the exception since it is not broken down into glucose, the Centers for Disease Control and Prevention says. Instead, fiber stays intact, aiding in digestion. Since fiber is not broken down, it does not provide energy in the form of glucose.
Digestion and Storage of Carbohydrates
The breakdown of carbohydrates begins in your mouth with the help of saliva. Chewing your food thoroughly also aids in this process, since it allows food to be completely engulfed in saliva. From there the bolus, or ball of chewed food, travels down the esophagus and into the stomach. Carbs spend the shortest amount of time in your stomach, as compared to protein and fat, the National Digestive Diseases Information Clearinghouse explains. Once carbohydrates hit the small intestine, they are broken down into glucose where they are immediately absorbed into the bloodstream. A hormone called insulin helps pull glucose into cells for energy and any leftover glucose is stored as glycogen in the liver and muscles.
Glucose Levels
Your diet should consist of 45 to 65 percent carbohydrates to keep adequate glucose in your blood, as well as keep your glycogen stores full. Carbohydrates provide 4 calories per gram, so if you follow a 2,000 calorie diet, you need 225 to 325g of carbs throughout the day. Blood glucose is normally low before a meal, between 70 to 130mg/dL, which may cause you to feel shaky or fatigued when it gets low. After a meal, you feel energized since your glucose is high, above 180mg/dL. Having diabetes causes your blood sugar to remain high for an extended period of time, since insulin is not pulling glucose into cells.
Ketones
Your body goes into ketosis when you don't consume adequate amounts of carbohydrates to sustain glucose in the blood and after your glycogen stores are used up. Ketosis causes your body to break down fat for energy, forming byproducts known as ketones. While ketones once in a while are probably not harming you, having constant high levels of ketones in your blood causes a poisonous disorder called ketoacidosis. Ketoacidosis is commonly associated with type 1 diabetes and can be life-threatening if left untreated. Beginning stages of ketoacidosis cause vomiting, extreme fatigue and fast breathing.
References
- Centers For Disease Control and Prevention; Carbohydrates; February 2011
- American Diabetes Association: Checking Your Blood Glucose
- National Digestive Diseases Information Clearinghouse; Your Digestive System and How It Works; April 2008
- National Diabetes Information Clearinghouse: Taking Care of Your Diabetes Every Day
