There are 3 primary macronutrients that humans consume for energy: protein, fat and carbohydrates.
Carbohydrates can be such a confusing topic. In this blog, I will be simplifying this complex macronutrient by addressing the following 5 questions:
- What are carbohydrates
- What are the 2 types of carbohydrates?
- How does the body use carbohydrates?
- How does the body regulate blood glucose levels?
- What is the glycemic index?
1. What are carbohydrates?
Carbohydrates are a source of ENERGY for your body, yielding 4 calories per gram. Your body converts ingested carbohydrates into GLUCOSE (blood sugar), which is then used for ENERGY for your cells, tissues and organs. Did you know that the brain relies on glucose from carbohydrates for energy? Without carbohydrates, your health would suffer. Examples of carbohydrates include cereal, bread, pasta, vegetables, fruit, rice, candy, and soft drinks.
2. What are the 2 types of carbohydrates?
Carbohydrates are classified as SIMPLE or COMPLEX, depending on their chemical structure.
They are classified as:
i) monosaccharides (mono = 1) eg. Glucose, fructose, lactose.
ii) disaccharides (di = 2): eg. two monosaccharides linked together.
Note: your body can only absorb monosaccharides into the bloodstream.
- include sugars found NATURALLY in fruits, vegetables and dairy products.
- include sugars ADDED during refining and processing of foods. eg. Candy, soft drinks, table sugar, corn syrup, fruit juice, cake, white bread, pasta made with white flour, all baked goods made with white flour, most packaged cereals.
- break down easily and tend to send your blood sugar levels quickly out of control. This means they:
- provide quick energy (sugar rush) because they break down easily, but are followed by a sugar crash (lethargy, mood swings and increased hunger)
- result in sugar cravings.
- are associated with a higher incidence of tooth decay, diabetes, cardiovascular disease and even cancer.
=polysaccharides (poly = many) and are found in starch and fibre. This complex molecular structure is more difficult for the body to break down, which helps stabilize blood sugar levels.
Note: your body must break them down into monosaccharides
- include whole grain breads, whole grain cereals, starchy vegetables, oatmeal, quinoa, brown rice, and beans.
- provide timed-released and sustained energy.
- make you feel satisfied or full after a meal.
- are high in fibre and improve your digestion.
- complex carbohydrates are, for the most part, released into the blood stream more slowly than simple carbohydrates.
Fact: Did you know that FRUIT is actually a SIMPLE carbohydrate? Fruit, however, is an abundant source of fibre, which slows its digestion and release into the blood stream, which is why it is often classified as a complex carbohydrate. This means you shouldn't be demonizing fruit! Be cautious of dried fruit; however, as it can add unwanted body fat in a very short time! Why? The dehydrating process concentrates the calories. A cup of fresh blueberries contains 84 calories, whereas a cup of dried blueberries contains a whopping 600 calories! Fresh fruit is the best option because it satisfies hunger longer (with less calories) due to the higher water and fibre content. Furthermore, dried fruit tends to stick to the grooves in your molars, causing tooth decay.
Fact: Sugar is sugar! The human body can break down different types of carbohydrates but ultimately produces the same thing in your bloodstream: glucose. Does this mean you should avoid fruits because of their natural sugar content? No! Fruit contains only modest amounts of sugar, but also contains fibre (which slows the release of sugar into the bloodstream), vitamin C, potassium, cancer-fighting antioxidents and other vital nutrients. Remember that weight gain is matter of “calories in” versus “calories out”, so if you consume more calories than you burn through activity, you will store fat. If you eat too much fruit, you will gain weight, just as you will gain weight if you eat too much of ANY food. Do not misconstrue: this does not mean you are doing yourself any favours by eating a junk food diet (because you won't get the vital micronutrition your body requires). Nor should you adopt the impractical attitude that you can “out-train” an unlimited diet. If you want to lose excess body fat and have a healthy body then your energy intake will have to be less than your daily calorie expenditure. Continue reading, and I will teach you precisely why certain carbohydrates will help and hinder your weight loss goals.
3. How does the body use carbohydrates?
After your body ingests and digests carbohydrates, the absorbed glucose will do one of the following:
1. It can burn the glucose immediately (providing immediate energy to your body)
2. If the glucose is not needed for immediate energy, the liver or muscles will convert it into glycogen for storage. Glycogen can later be converted to glucose when the body once again needs energy.
- muscle glycogen provides energy to muscles.
- liver glycogen provides energy to any part of the body.
4. How does the body regulate blood glucose (blood sugar) levels?
If your blood sugar level increases, then the pancreas releases the hormone INSULIN into the blood.
- Insulin signals fat, liver and muscle cells to absorb the glucose.
- This lowers your blood glucose back to a stable level.
- Occurs when you eat.
If your blood sugar level decreases, then the pancreas releases GLUCAGON.
- Glucagon signals the liver to break down its stored glycogen, which releases glucose into the blood.
- This raises your blood glucose back to a stable level
- This happens between you are fasting (i.e. not eating).
5. What is the Glycemic Index?
Your blood sugar and insulin levels depend on the type of carbohydrate consumed. Simple carbohydrates are released more quickly into the bloodstream than complex carbohydrates. The more quickly the carbohydrate is released into the bloodstream, the higher your blood sugar and insulin levels will be. Elevated insulin levels impair fat oxidation (meaning, insulin prevents your body from breaking down your stored fat).
The Glycemic Index indicates the rates at which certain carbohydrates are formed into glucose and released into the bloodstream. The faster the glucose is released into the bloodstream, the more the body will secrete insulin in response.
Low Glycemic Index Carbohydrates
- provide sustained energy levels
- slower absorption into the bloodstream
- lowered insulin response
- alleviate hunger, controls appetite
- prevent mood swings and fatigue
- result in higher muscle glycogen levels
High Glycemic Index Carbohydrates
- provide quick energy (sugar rush)
- quicker absorption into the bloodstream
- higher insulin response
- result in a sugar crash (hypoglycemia)
- lead to mood swings and lethargy
- leads to increased hunger/sugar cravingt
Low Glycemic Index Carbohydrates
- fructose (found in fruit)
- Fruit: apples, berries, oranges, pears, grapefruit, peaches, green grapes, plums, kiwi, melon, papaya, bananas
- Vegetables: sweet potato, yam, asparagus, broccoli, cauliflower, celery, cucumbers, tomatoes, spinach, peppers, eggplant, squash, zucchini, green peas, snow peas, green beans, lettuce
- skim milk, whole, low fat yogurt
- legumes: chickpeas, soya beans, kidney beans, black beans
- whole grains: 100% whole grain bread, brown rice, oatmeal (non-instant)
- All Bran cereal
- surprising but true: chocolate, m&m’s, potato chips, popcorn, low fat ice cream, whole milk , pound cake, apple juice, grapefruit juice, orange juice, pineapple juice (but these are high in calories and sugar).
High Glycemic Index Carbohydrates
- glucose, maltose
- puffed & flaked cereals , instant oatmeal
- RICE CAKES!!! Yes! RICE CAKES!
- candy, jelly beans
- white bread, white flour, white pasta, white rice
- pretzels, soda crackers, corn chips
- cakes, donuts, waffles, ice cream
- fruit: dried dates, watermelon, lychee, very ripe banana
- vegetables: baked or mashed potatoes, fries, parsnips, pumpkin, carrots
- legumes: lima beans
- electrolyte sports drinks
If you really want to slow the entry of glucose into the bloodstream, then eat your low-glycemic and high fibre carbohydrate in conjunction with a lean protein or a healthy fat. Why? Protein and fibre take time for the body to break down and absorb, and fat slows the emptying of stomach contents and food absorption. Another technique to lower the total glycemic index of a meal is to combine a high glycemic carbohydrate with a low glycemic carbohydrate. For example, if you eat a baked potato (high glycemic index) with a cucumber (low glycemic index), the total glycemic index will be lower than if you had only eaten the potato.
NOTE: The Glycemic Load is a more accurate way to select healthy carbohydrates because it not only considers a food’s glycemic index, but also the amount of carbohydrates per serving. For example, carrots and watermelon have a high glycemic index, but are low in carbohydrates, which means they have a low glycemic load. Carrots and watermelon are superbly nutritional, but have been wrongly given a bad reputation because of their high glycemic index rating. Consider m&m’s candy and ice cream. Although they have a low glycemic index, we all know these sugary high-fat calorific foods are not a "healthy" food choice. We now understand that the high fat content of these foods explains why they have a low glycemic index rating. In other words, always think critically!
p.s. I eat carbs at night! I don't demonize carbs either. I eat between 200 and 300g of carbs a day! Correct! Click here to learn more about my diet.