Carbohydrates have gotten a lot of bad publicity through the years. Before we toss them out of our diet completely it’s important to know what they are and understand the vital role they play in our bodies.
I’m going to try to keep it as simple and cohesive as I can.
Carbohydrates are one of the three primary macronutrients in our diet, including fat and protein. They are called Macronutrients because they are needed in large quantities. All carbohydrate molecules contain carbon, hydrogen, and oxygen atoms in specific ratios. Thus, in the nutrition and chemistry world carbohydrates are often referred to as CHO.
The most basic fundamental unit of a carbohydrate is a monosaccharide (“one” sugar). Monosaccharide examples are glucose, galactose, and fructose. These along with disaccharides (“two” sugars) are considered simple carbohydrates. Oligosaccharides or polysaccharides (“three or more” sugars) are considered complex carbohydrates.
The primary role of carbohydrates in the body are to provide energy, store energy, and spare protein and fat for other uses. Carbohydrates also facilitate blood glucose and insulin metabolism, promote good digestive health, lower cholesterol, and lower your risk for other health issues such as heart disease and diabetes.
Digestion, Absorption, Energy, and Storage
Upon food consumption, the digestive tract begins to break down carbohydrates into glucose, which then enters your intestines where it’s absorbed. From there, it passes into your bloodstream. The glucose in your blood stream is used for immediate energy and the extra is turned into glycogen and stored in your muscle and liver cells.
Your body is designed to keep a homeostatic (balanced) state at all times. It’s quite awesome actually!
When you eat food, beta cells in your pancreas monitor your blood glucose levels. When your blood glucose rises upon eating, the beta cells release insulin into your blood stream. Think of insulin as a key- it unlocks muscle, fat, and liver cells so glucose can get inside. After your body has the energy it needs, the leftover glucose is stored as glycogen in your muscle and liver cells to use when energy is needed again.
When you haven’t eaten for a few hours, your blood glucose level drops. Your pancreas stops pumping out insulin. Alpha cells in the pancreas begin to produce a different hormone called glucagon. Glucagon signals the liver to breakdown stored glycogen and turn it back into glucose- and "boom" you have energy back!
Most of the cells in your body use glucose, along with amino acids (building blocks of protein) and fats for energy. If glucose is present, it will be the main source of fuel for your brain and body. In the absence of glucose, energy can be made from either the breakdown of protein (generally from your muscle tissue-not good) or the breakdown of fatty acids in the form of ketone bodies. This can happen overnight, during dieting, and/or times of fasting.
There are three types of carbohydrates we consume: starch, sugar, and fiber. These carbohydrates are also known as simple and complex carbohydrates.
Complex carbohydrates are known as the “healthier” sources, since they are rich in vitamins, minerals, and fiber. Due to their structure they also have a blunted effect on on blood glucose since they take some time to digest (remember those "three or more" sugar compounds?) Complex carbohydrates have been linked to a variety of health benefits such as reduced cholesterol, enhanced digestive health, and reduced risk for chronic health conditions such as cardiovascular disease, type 2 diabetes, and other metabolic disorders. Complex carbohydrates include whole grains, vegetables, fruits, and legumes.
Simple carbohydrates are generally what gives carbohydrates their stigma and include white bread, sodas, pastries, and other highly processed foods. Simple carbohydrates contain less (if any) nutrients, easier to digest, and cause spikes in blood glucose levels. Unfortunately, simple carbohydrates tend to be highly palatable and calorie dense, therefore we have more of a tendency to overeat them which can be a double whammy!
Also, it's important to note that for every gram of carbohydrate we consume, we hold onto about 3 molecules of water. Unless you went on a three day food gorge, the increase increase you see on the scale 24-48 hours after a carb heavy meal (like the traditional Thanksgiving turkey meal with all the trimmings) is water weight, not fat. This is also a contributor to the initial Atkins diet "whoosh" people speak about. Most people can lose up to 10lbs. of water weight after a couple weeks after starting Atkins!
Truth: Carbohydrates alone don't make us "gain weight", but over time eating ANYTHING in excess will!
I digress, so let me get back on track.
Glycemic index (GI) is a tool used to track carbohydrates and their individual effects on blood sugar levels. It has been shown to be a beneficial way to structure a diet for those with type 2 diabetes.
The GI scale ranks carbohydrates from 0 to 100 based on how rapidly the rise in blood glucose occurs at consumption. Low GI foods (55 or less) produce a gradual spike in blood sugar. These foods include steel-cut oatmeal, oat bran, muesli, sweet potatoes, peas, legumes, most fruits (apples, blueberries, grapefruit, peaches, plum, strawberries, etc.), and non-starchy vegetables. Medium GI foods (56-69) include quick oats, some fruit (underripe bananas, figs, kiwi, oranges, and grapes), brown rice, whole-wheat bread. High GI foods (70-100) include white bread, some fruit (pineapple, over-ripe bananas, watermelon, dried dates), pastries, sugary drinks, instant oatmeal, corn flakes, white potatoes, pretzels, rice cakes, cereal, and popcorn. High GI foods increase the risk for type 2 diabetes, heart disease, and obesity.
Carbohydrate Take Home
There is much debate about whether we truly need carbohydrates to survive and if they are really “essential” in our diets.
I think it’s important to recognize all the nutrients carbohydrates CAN provide in a (balanced) diet and remember not all carbohydrates are considered equal so choose wisely!
Limit simple carbohydrates like white bread, pastries, sugary drinks, and many other of the highly processed foods. Choose complex carbohydrates which provide the essential vitamins, minerals, and fiber our bodies need and help prevent and/or manage conditions such as type 2 diabetes, cardiovascular disease, and other metabolic disorders.
For those with Type 2 diabetes, following a low GI diet may be beneficial to help manage blood glucose levels. Talking with your doctor about what plan of action you can take may be advantageous for your health and the management of your condition.