Carbohydrate: Carbohydrates are a form of macronutrient that chemically consist of carbon, hydrogen and oxygen. Essentially, carbohydrates represent sugar which the body can digest and then use for energy. They include the sugars, starches, and fibers of fruit, grains, vegetables and dairy. Carbohydrates are important because they can be quickly turned into energy and can fuel work such as working muscle during exercise.
Carbohydrate exist in simple and complex forms. Simple carbs consist of one or two sugars (e.g. fructose – fruit sugar; one sugar called monosaccharide and two sugars called disaccharide) and because of their simplicity in structure, they are absorbed more quickly into your blood stream.
Refined carbohydrates are an example of simple carbs except, due to their processed nature, they lack vitamins, minerals and fibers which raw fruit retains. Examples of refined carbohydrates are found in candy, soda, white bread, pasta; anything with high fructose corn syrup, etc. Since these carbs lack complex nutrients such as fiber, they are quickly absorbed and rapidly increase your blood sugar. Long term consumption of these simple carbs can result in numerous metabolic complications including but not limited to: weight gain, fatty liver, increased blood sugar, lethargy, heart disease, etc.
Complex carbohydrates contain 3 or more sugars and are found in more starchy food sources like beans, nuts, corn, sweet potatoes, whole grain bread, etc. Due to fiber and mineral content these carbs are digested more slowly and therefore do not rapidly spike blood sugar but rather offer a more sustained longer-term source of energy.
U.S. Dietary Guidelines suggest that daily nutrient intake of carbohydrates should consist of 45 to 65 percent of total calories such that if you consume 2,500 calories per day you would take in 1125-1625 calories derived from carbohydrates or approximately 281grams to 406 grams of carbohydrate (4 calories per gram of carbohydrate). For more detailed info go here: http://www.ift.org/knowledge-center/focus-areas/food-health-and-nutrition/dietary-guidelines.aspx
What about low carbohydrate diets? When you consume carbohydrate your blood level of sugar increases and this is sensed by your pancreas. As a response, the pancreas then secretes insulin into your blood which signals to important tissues such as skeletal muscle and fat to go ahead and take up the sugar and use it for energy thereby lowering your blood level of sugar. However, often times chronic and excessive intake of carbohydrates (particularly simple and refined carbohydrates) over-stress the ability of the pancreas to produce and secrete insulin. As a consequence, insulin loses the ability to cause sugar uptake into tissues. This results in chronically high levels of blood sugar and can lead to a host of metabolic issues e.g. diabetes, fatty liver disease. A way to try to counter this problem, as well as potentially lose weight, is to adopt a low-carbohydrate diet where generally 20-60 grams of carbohydrate are consumed daily. Bear in mind, this is not an easy eating change to make and people often encounter headaches, some weakness, and can feel emotional due to the low levels of sugar intake. To counter these, individuals should focus on increase intake of lean protein (chicken, lean beef, fish) as well as healthy fats (nuts, avocado, coconut oil) to help with feeling full. For more detailed info go here: https://www.mayoclinic.org/healthy-lifestyle/weight-loss/in-depth/low-carb-diet/art-20045831
From a personal experience, I adopted a low carbohydrate diet about 8 months after I began CrossFitting. For me, it was really difficult at first not consuming some of my go to carbs like bread and especially cereal! Over time, I began to really increase my protein intake and also began consuming more protein and fats in the form of eggs and nut butter and the “sugar crashes” subsided. I didn’t really count calories of grams of carbs, I just focused on staying away from processed high carbohydrate items and focused again on the protein side of things. In doing so, I did drop between 5-8 pounds (bear in mind carbs have high water content which can result in weight gain or loss) but I really noticed a change in my body composition whereby my body fat percentage dropped a few points.
Want to check out more on carbs and movement? Check out this CrossFit resource: