What Are Carbohydrates?
Carbohydrates, along with fats and proteins, are one of the three main classes of food. Carbohydrates are organic compounds consisting mainly of sugars, starches and fiber.
Plants make carbohydrates during photosynthesis and store them as any of the saccharides (sugars) described below. They are used primarily for energy in the body. If carbohydrate isn't used in short order, it is stored. A certain amount can be stored in the liver and muscles as glycogen, and the rest is stored as fat.
Unlike protein and essential fats, our bodies can get along without dietary carbohydrate if needed.
What is a Low-Carb Diet?
The term "low-carb diet" (also called "reduced carbohydrate", or "low-glycemic" diet) is a broad term, encompassing many popular diet books (Atkins, South Beach, Zone, Protein Power, Sugar Busters) as well as eating plans that don't follow a rigid format, but advise limiting the consumption of foods that are high in carbohydrate and/or are especially glycemic (raise blood sugar).
When you read the research about low-carb diets, "low-carb" is defined in many different ways. One difference is whether they are looking at the amount of carbohydrate in the diet or the percentage of calories from carbohydrate.
The other difference is "how low?" The usual carbohydrate recommendations from the U.S. Dietary Guidelines and similar sources for the general public are that 50-65% of the calories in a person's diet should be from carbohydrate, so anything less than that is sometimes considered "low-carb".
Studies of low-carb diets have ranged from 45% down to 5% , and authors of diet books are similar.
