Carbs: The Breakdown

donuts.jpg

What are carbs?

Carbohydrates are found in a wide variety of foods including bread, rice, milk, potatoes, pasta, fruit, soft drinks, and pie. They also come in an array of forms – the most common forms are sugars, fibers, and starches.

The basic building block of every carbohydrate is a sugar molecule: a simple union of carbon, hydrogen, and oxygen. Starches and fibers are essentially chains of sugar molecules. Some contain hundreds of sugars (1). Carbohydrates can generally be grouped into two categories: simple carbohydrates and complex carbohydrates.

What is the difference between simple and complex carbohydrates?

Simple carbohydrates include sugars such as fruit sugar (fructose), corn or grape sugar (dextrose or glucose), and table sugar (sucrose).

Complex carbohydrates include everything made of three or more linked sugars.

The general idea has been that simple carbohydrates are good while complex carbohydrates are bad, particularly in terms of diet and weight loss. Though this is true on a chemical basis, carbohydrates and how they are digested is a little more complicated.

How do carbs benefit our bodies?

Like almost any kind of food, our digestive system handles carbohydrates by “attempting” to break them down and converting them into single sugar molecules so that they are able to be absorbed into the bloodstream. It also converts most digestible carbohydrates into glucose (also known as blood sugar), because cells are designed to use this as a universal energy source. As blood sugar levels rise, the pancreas creates special hormones called insulin that signals for cells to absorb blood sugar for energy and storage. As more and more blood sugar begins to be absorbed into the cell, its levels in the bloodstream begin to fall. That’s when the pancreas starts making glucagon, a hormone that tells the liver to start releasing stored sugar. This ensures that every cell in your body has a steady supply of blood sugar (1).

What is fiber in relation to carbohydrates?

Fiber is put together in such a way that it can’t be broken down into sugar molecules, and so it passes through the body undigested. Fiber comes in two forms: soluble fiber dissolves in water, while insoluble fiber does not. “Although neither type nourishes the body, they promote health in many ways. Soluble fiber binds to fatty substances in the intestines and carries them out as waste, thus lowering low-density lipoprotein (LDL, or bad cholesterol). It also helps regulate the body’s use of sugars, helping to keep hunger and blood sugar in check. Insoluble fiber helps push food through the intestinal tract, promoting regularity and helping prevent constipation. Adults need at least 20 to 30 grams of fiber per day for good health. But most Americans get only about 15 grams a day” (1).

How is insulin related to diabetes?

People with diabetes have trouble when it comes to the interplay of insulin and glucagon. People with type 1 diabetes don’t make enough insulin, so their cells can’t absorb sugar. People with type 2 diabetes have a different kind of problem where their cells don’t respond well to insulin. “This condition, known as insulin resistance, causes blood sugar and insulin levels to stay high long after eating. Over time, the heavy demands made on the insulin-making cells wears them out, and insulin production slows, then stops. A sedentary lifestyle, being overweight, genes, and a diet rich in processed carbohydrates all promote insulin resistance and can be linked to diabetes” (1).

What is the Glycemic Index?

As stated earlier, carbohydrates are a little more complicated than categorizing simple carbs as bad and complex carbs as good. For example, French fries and starch in white bread qualify as complex carbohydrates. However, the body converts this starch to blood sugar nearly as fast as it processes pure glucose. This causes rapid spikes in blood sugar which promotes insulin resistance. Foods like whole oats and whole grains are digested more slowly, causing a lower and gentler change in blood sugar. The glycemic index aims to classify carbohydrates based on how quickly and how high they boost blood sugar compared to pure glucose.

Glycemic Index

Many factors can affect a food’s glycemic index, including the following:

  • Processing: Grains that have been milled and refined—removing the bran and the germ—have a higher glycemic index than whole grains.
  • Type of starch: Starch comes in many different configurations. Some are easier to break into sugar molecules than others. The starch in potatoes, for example, is digested and absorbed into the bloodstream relatively quickly.
  • Fiber content: The sugars in fiber are linked in ways that the body has trouble breaking. The more fiber a food has, the less digestible carbohydrate it contains, and so the less sugar it can deliver.
  • Ripeness: Ripe fruits and vegetables tend to have more sugar than unripe ones, and so tend to have a higher glycemic index.
  • Fat content and acid content: The more fat or acid a food or meal contains, the slower its carbohydrates are converted to sugar and absorbed into the bloodstream.
  • Physical form: Finely ground grain is more rapidly digested, and so has a higher glycemic index, than more coarsely ground grain.

Carbs and weight loss

In a year-long study, published in 2007 in the Journal of the American Medical Association, overweight, premenopausal women were put on four types of diets: Atkins (a popular no carb diet), Zone, Ornish, or LEARN (a standard low-fat, moderately high-carbohydrate diet). In all four groups, the participants steadily lost weight in the first six months, with the most rapid weight loss occurring among the Atkins dieters. However, after the first six months, the women started to regain the weight. At the end of the year, the participants in the Akins group lost the most weight, about 10 pounds, compared with a loss of almost 6 pounds for the LEARN group, 5 for the Ornish group, and 3.5 for the Zone group. Though almost all the participants lost weight with their respective diets, the study showed that few of the women actually stuck with their diets after the study was over. More importantly, they rebounded. The women in the Atkins diet group, who had to restrict their carbohydrate intake to less than 50 grams a day, took in triple that amount. Similar deviations were also found in the other group of diets.

The study shows that the most important component for losing weight and keeping it off long-term is to pick a dietary lifestyle that best suits you but is also full of healthy, clean foods. Yes, restricting yourself from carbs can help you lose weight fast, but as the study pointed out, it is also a strong possibility that you can rebound and gain the weight back twice as fast. If carbs have always been a big part of your diet, you shouldn’t cut them out completely. The idea is to choose healthy carbs that are unprocessed and high in fiber.

Sources 

1. “Carbohydrates: Good Carbs Guide the Way.” The Nutrition Source. Harvard School of Public Health, n.d. Web. 08 Feb. 2013.