Carbohydrates (Carbs) are one of the three major macronutrients and the most important source of energy for our bodies. Carbs contain 4 calories per gram and should represent 50-55% from our daily intake. There are two major categories, simple and complex carbs.
Depending on their chemical structure, carbs form three categories:
1. Carbs with just one molecule :
- glucose (in fruits, honey)
- fructose (in fruits, vegetables)
- galactose (in milk)
2. Carbs with two molecules (combination of 2 one-molecule carbs) :
- sucrose = glucose + fructose (in sugar)
- lactose = glucose + galactose (in diary)
- maltose = glucose + glucose (in malt, beer, corn)
Categories 1 and 2 represent simple carbohydrates.
3. Complex carbohydrates, with hundreds of glucose molecules :
starch (found in cereals: wheat, rye, oatmeal, barley, rice, quinoa; in tubers: potatoes, yams, Jerusalem artichoke; in roots: carrots, beets, yellow turnip; dried vegetables: beans, lentils, pea, chickpea, soy; in fruits: oranges, apples, pears, apricots, plums, figs, bananas, chestnuts, avocados, tomatoes; in fresh vegetables: green beans, broccoli, cabbage, zucchini, peppers, eggplant, artichoke, asparagus);
- dietary fibers, that can be :
soluble (in apples, citrus, pears, strawberries, vegetables, oatmeal) or
insoluble (in beans, brown rice, corn, lentil, pea, whole bran, whole cereals, whole pasta, whole bread).
These fibers are very important, because they adjust the intestinal transit, and therefore decrease the risk of colorectal cancer, decrease cholesterol levels, and stop the increase of blood glucose.
The glycemic index (GI) estimates how much each gram of available carbohydrate (total carbohydrate minus fiber) raises a person’s blood glucose level, following food consumption, relative to the consumption of pure glucose (the defining standard). Glucose has a glycemic index of 100.
Food with :
- low GI (5-35) will help you lose weight
- medium GI (40-50) will help you prevent weight gain
- high GI (55 and above) will make you gain weight.
There are plenty of GI tables and charts available on the internet, where you can find hundreds of food GIs.
Another important element when talking about this subject is the carbohydrates concentration, which is the number of grams of carbohydrates that can be found in 100g of food. For example foods with high GI can have a low carb concentration, so these can be eaten in a small amounts, without having a disastrous effect on your weight.
Complex carbohydrates are a very good source of energy, are full of nutrients, minerals and vitamins, have a slower absorption and lowered insulin response, can alleviate hunger and lead to a controlled appetite. Conversely, refined sugar products (all kind of sweets, sodas, pastries, refined grains, products prepared from refined flour) don’t have any kind of nutritional benefits; they are just “empty calories”, are quickly absorbed and have a high insulin response that will turn on hunger and the fat storing mechanisms. An increased intake of carbohydrates will cause in time overweight, obesity, diabetes, dyslipidemia, increased blood pressure, dental cavities and even more serious health problems.
In conclusion, we could say that “friendly” carbs are complex carbohydrates (that have a low GI or a low carb concentration) and “not so friendly” carbs are simple carbohydrates (those with a high GI, with a high carb concentration).