What are carbohydrates?
Carbohydrates are organic molecules that are made up of a collection of carbon, hydrogen, and oxygen molecules; all carbohydrates have a 2:1 ratio of hydrogen to oxygen.
Typically, because of their similar chemical structures, sugars, starches, and fibers are all considered carbohydrates. Further, they can be divided into three general groups of saccharides (sugar) based on their level of complexity:
- monosaccharides: the simplest form of carbohydrate
- oligosaccharides: saccharide composed of a small number of monosaccharides
- polysaccharides: more than about 10 linked monosaccharides that form a polymer
In addition, we can further breakdown the classification into two types of carbohydrates: simple and complex.
Simple carbohydrates are smaller, more easily processed molecules known as mono- and disaccharides since they contain either one sugar molecule or two sugar molecules linked together.
Complex carbohydrates, on the other hand, are called polysaccharides since they have more than two sugar groups linked together.
Carbohydrate digestion breaks down more complex forms of carbohydrates into the monosaccharides glucose, fructose, and galactose, for eventual release into the bloodstream as glucose.
Each subtype of carbohydrate has different effects in the human body depending on its structure and its food source, which affect things like:
- How quickly and/or easily the carbohydrate molecule is digested and absorbed
- Which other nutrients are provided along with the carbohydrate source; for example, fat and protein slow down the digestion and/or absorption
- Our perceptions of the carbohydrates’ texture and sweetness
- Enzyme action in the mouth and gut
With that said, eating the “healthier“, high fiber, lower glycemic index carb (oatmeal bowl) will be absorbed much slower while the “non-healthy” carbs (sugar cube) are digested very quickly.
Also, carbohydrates are primarily a source of immediate energy for all of your body’s cells.
Carbohydrates & blood sugar
Typically, 20 grams of blood-borne glucose circulates every hour, and the body prefers to keep this more or less stable.
If our blood sugar drops below that, the body will immediately use the new glucose supply for preserving blood glucose levels for immediate energy.
If excess glucose is present, the liver and muscles will uptake what they can.
The liver can store about 80 to 100 grams of glycogen before its full.
Muscles can store between 300 and 600 grams of glycogen before they’re full (depends on the amount of muscle mass someone has).
Beyond this, additional glucose can be transformed into fat.
Second, foods that have a high glycemic index (measure of how quickly and significant a food can raise blood sugar) can raise blood sugar rapidly which causes a spike in insulin to try and control the “sugar load” in the body.
Carbohydrates in your diet
When the diet consists of simple sugars and refined carbohydrates (which the body breaks down rapidly; remember glycemic index), one may notice elevations in blood triglyceride levels, bad cholesterol, and insulin resistance.
On the other hand, carbohydrates that are digested and absorbed slowly, such as whole grains, fruits, and vegetables, can help to control insulin response, energy levels, and body composition.
Such unrefined, unprocessed, complex carbohydrate sources may reduce triglycerides and improve one’s cholesterol profile.
Other benefits of a lower glycemic diet include increased vitamin and mineral intake, increased fiber intake, enhanced satiety, a higher thermic effect of feeding, and blood sugar control.
The chart below compares the glycemic response (i.e., the rise in blood glucose levels) between eating a high-GI food (glucose) and a low-GI food (beans). Notice how with glucose (red area), blood glucose rises quickly and peaks shortly after ingestion.
The Dietary Guidelines Committee has suggested a minimum intake of 130g of carbohydrate per day to meet basic energy needs and supply the brain with enough glucose.
However, many experts suggest the body can do fine with a much lower amount, assuming adequate intake of dietary fat and protein.
In summary, carbohydrates are important and required for optimal functioning. The best carbohydrates to ingest are:
- the slow digesting,
- high fiber carbohydrates.
These tend to be the highest in micronutrients and tend to better control daily food intake.
There is one exception to this rule: After intense, carbohydrate-depleting exercise, rapid digesting carbohydrates can be consumed to hep replenish carbohydrate stores.
In addition, a slower carbohydrate breakdown from lower glycemic carbohydrates is better for satiety, blood sugar, and body composition. These carbohydrates are found in vegetables, fruits, legumes, and whole grains.
Lastly, consume at least 25 grams of fiber per day from vegetables, fruits, legumes, nuts, seeds, and whole grains to ensure optimal health and body composition.
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