The three basic nutrients that our body needs in relatively large quantities are called macronutrients. These nutrients are used to build and repair tissues, regulate proper bodily function and provide the bulk of our energy. They are an essential part of the human diet and vital for survival.
The three macronutrients are carbohydrates, proteins and fats.
Carbohydrates provide fuel for our body. The building blocks of carbohydrates are carbon, hydrogen and oxygen. As we ingest carbohydrates, they are turned into glucose and distributed through our bloodstream as a source of energy to fuel the muscles and brain. If they are not needed immediately, the carbohydrates will be converted into glycogen and stored in the muscles and liver for future use (like an energy reserve). Any excess carbohydrates that cannot be used as glucose or stored as glycogen, are converted to fatty acids, or body fat.
Carbohydrates can be broken down into two categories, simple and complex.
Simple Carbohydrates – “Sugar,” “High GI,” “Artificial”
These carbohydrates, such as chocolate and soda are “simple” because they’re easily broken down and digested. They rush into our bloodstream, absorb quickly and provide a quick boost of energy. The body’s natural defense mechanism is to trigger the hormone insulin to help neutralize the sugar. The insulin does its job, but it decreases our blood sugar to levels below normal. This results in a “sugar crash,” the sense of needing more fuel, energy and calories, leaving us craving more simple carbohydrates and reigniting the cycle. We end up eating more calories than we need and the body’s only option is to store the excess carbohydrates as fat.
Simple carbohydrates are usually processed or refined and considered “empty calories” because they do not provide any nutritional benefits. These foods are void of vitamins and minerals. They’ve been shown to cause wild swings in blood sugar levels, which leads to cravings, compulsive eating, weight gain and even mood swings. Over consumption of simple carbohydrates has been associated with a higher incidence of cardiovascular disease, diabetes and other diseases.
Not all simple carbohydrates are bad, however. Natural, unprocessed carbohydrates such as fruit and honey contain digestive enzymes, vitamins and other nutritional benefits.
Examples of Simple Carbohydrates
Complex Carbohydrates – “Starchy,” “Low GI,” “Natural”
These carbohydrates, such as grains and vegetables, are “complex” because our digestive system has to work harder to break them down. They digest slowly, resulting in a steady stream of energy flowing into our bloodstream. These carbohydrates do not produce an overproduction of insulin because they do not overwhelm our body with a large amount of sugar all at once. The time-release effect keeps us feeling full longer, stabilizes blood sugar levels and provides a sustained energy source – keeping our energy at an even level.
Complex carbohydrates are natural, whole foods and they offer several nutritional advantages over simple carbohydrates. These foods inherently contain more vitamins, minerals and digestion improving, fiber. Diets rich in complex carbohydrates have been shown to lower cholesterol, and reduce the risk of high blood pressure and heart disease.
Examples of Complex Carbohydrates
The Glycemic Index (GI)
The Glycemic Index (GI) is a relatively new method of ranking carbohydrates by the extent to which they impact blood sugar levels. It was first popularized about ten years ago and caught major publicity from diet programs like the South Beach Diet. It’s based on a scale that ranges from 0 to 100. High GI (>70) foods are characterized by quick absorption rates and large fluctuations on blood sugar levels. Low GI (<55) foods are characterized by slow absorption rates and a gradual rise in blood sugar levels.
Less than 55 are "low" (mostly complex carbohydrates)
55 <–> 70 are "medium"
More than 70 are "high" (mostly simple carbohydrates)
The general consensus is that high GI foods should be avoided because they spike blood sugar levels, igniting the overproduction of insulin, the process that stores excess glucose as fat. The index has several flaws, however.
1. The index only lists single foods. When we combine several foods to prepare a meal, it lowers the value of the Glycemic Index.
2. Food preparation (boiling, frying, baking, etc.) alters the value of the Glycemic Index.
3. The Glycemic Index is not a one size fits all; people have different individual blood glucose responses and results may vary.
4. Foods that are considered unhealthy have low GI values (i.e. ice cream, cake, chocolate).
* Use the Glycemic Index as a general guide and not an absolute reference.
In the next post, we'll discuss protein and fat!