Carbohydrates
Carbohydrates perform numerous roles in living organisms. Saccharides and their derivatives play key roles in the immune system, fertilization, preventing pathogenesis, blood clotting, and development.
Carbohydrate are divided into four chemical groupings: monosaccharides, disaccharides, oligosaccharides, and polysaccharides. In general, the monosaccharides and disaccharides, which are smaller (lower molecular weight) carbohydrates, are commonly referred to as sugars.
Monosaccharides are the major source of fuel for metabolism, being used both as an energy source (glucose being the most important in nature) and in biosynthesis. When monosaccharides are not immediately needed by many cells they are often converted to more space-efficient forms, in humans, this storage form is glycogen, especially in liver and muscle cells.
Carbohydrates are a common source of energy in living organisms; however, no carbohydrate is an essential nutrient in humans. Carbohydrates are not essential for the synthesis of other molecules. Humans are able to obtain 100% of their energy requirement from protein and fats.
Following a diet consisting of very low amounts of daily carbohydrate for several days will usually result in higher levels of blood ketone bodies than an diet with similar calories and similar protein content. This relatively high level of ketone bodies is commonly known as ketosis and is very often confused with the potentially fatal condition often seen in type 1 diabetics known as Diabetic ketoacidosis. Somebody suffering ketoacidosis will have much higher levels of blood ketone bodies along with high blood sugar, dehydration and electrolyte imbalance. Thus it is important to keep carbohydrates in your diet.
Mechanism
Simple Vs Complex
Carbohydrates are often categorized as either simple or complex. However, the exact distinction between these groups can be ambiguous. Usually carbohydrates are categorized chemically: simple if they are sugars (monosaccharides and disaccharides) and complex if they are polysaccharides (or oligosaccharides).
The simple vs. complex chemical distinction has little value for determining the nutritional quality of carbohydrates. Some simple carbohydrates (e.g. fructose) raise blood glucose slowly, while some complex carbohydrates (starches), especially if processed, raise blood sugar rapidly. The speed of digestion is determined by a variety of factors including which other nutrients are consumed with the carbohydrate, how the food is prepared, individual differences in metabolism, and the chemistry of the carbohydrate.
Simple carbohydrates generally break down into glucose and into the blood faster than complex carbohydrates.
Simple
Complex
Glycaemic Index & Glycaemic Load
The Glycaemic Index (GI) and Glycaemic Load concepts have been developed to characterize food behaviour during human digestion. They rank carbohydrate-rich foods based on the rapidity and magnitude of their effect on blood glucose levels.
The Glycaemic Index is a measure of how quickly food glucose is absorbed, while glycaemic load is a measure of the total absorbable glucose in foods. The insulin index is a similar, more recent classification method that ranks foods based on their effects on blood insulin levels, which are caused by glucose (or starch) and some amino acids in food.
The introduction of the Glycaemic Index has proven to be beneficial in knowing the rates at which certain carbohydrates are released into the blood stream. The Glycaemic index is a measure of how quickly a particular carbohydrate is formed into glucose and enters the body. It has shown certain complex carbohydrates to actually absorb quicker than simple carbohydrates.
The more glucose that reaches the blood in the first three hours after consumption, the higher the GI for that carbohydrate.
Low Glycaemic Carbohydrates
High Glycaemic Carbohydrates
Insulin Index
The Insulin Index is a measure used to quantify the typical insulin response to various foods. The index is similar to the Glycaemic Index and Glycaemic Load, but rather than relying on blood glucose levels, the Insulin Index is based upon blood insulin levels. This measure can be more useful than either the Glycaemic Index or the Glycaemic Load because certain foods (e.g., lean meats and proteins) cause an insulin response despite there being no carbohydrates present, and some foods cause a disproportionate insulin response relative to their carbohydrate load.
This index is not based on regular portions, but on eating 239 Calories of that food. So while apples have a higher insulin/glucose index than white pasta, it shouldn't then be considered that they're less healthy; because in 1 sitting most people eat a portion of apple smaller than that (~100 Calories per regular size apple) and a normal portion for spaghetti is closer to 500 Calories.
Below is a table of the Insulin Index:
| Smarter Health and Fitness Insulin Index Analysis | |||
|---|---|---|---|
| Food | Glucose Score | Insulin Score | Satiety Score |
| Jellybeans | 118 ± 18 | 160 ± 16 | 118 |
| Mars Bars | 79 ± 13 | 122 ± 15 | 70 |
| Potatoes | 141 ± 35 | 121 ± 11 | 323 |
| Baked Beans | 114 ± 18 | 120 ± 19 | 168 |
| Yogurt | 62 ± 15 | 115 ± 13 | 88 |
| White Bread (baseline) | 100 ± 0 | 100 ± 0 | 100 |
| Whole-meal Bread | 97 ± 17 | 96 ± 12 | 157 |
| Cookies | 74 ± 11 | 92 ± 15 | 120 |
| Ice Cream | 70 ± 19 | 89 ± 13 | 96 |
| Crackers | 118 ± 24 | 87 ± 12 | 127 |
| Grapes | 74 ± 9 | 82 ± 6 | 162 |
| Cake | 56 ± 14 | 82 ± 12 | 65 |
| Bananas | 79 ± 10 | 81 ± 5 | 118 |
| Croissants | 74 ± 9 | 79 ± 14 | 47 |
| White Rice | 110 ± 15 | 79 ± 12 | 138 |
| Cornflakes | 76 ± 11 | 75 ± 8 | 118 |
| Doughnuts | 63 ± 12 | 74 ± 9 | 68 |
| French Fries | 71 ± 16 | 74 ± 12 | 116 |
| Brown Rice | 104 ± 18 | 62 ± 11 | 132 |
| Crisps | 52 ± 9 | 61 ± 14 | 91 |
| Oranges | 39 ± 7 | 60 ± 3 | 202 |
| Apples | 50 ± 6 | 59 ± 4 | 197 |
| Fish | 28 ± 13 | 59 ± 18 | 225 |
| Grain Bread | 60 ± 12 | 56 ± 6 | 154 |
| Popcorn | 62 ± 16 | 54 ± 9 | 154 |
| Beef | 21 ± 8 | 51 ± 16 | 176 |
| Muesli | 43 ± 7 | 46 ± 6 | 100 |
| Cheese | 55 ± 18 | 45 ± 13 | 146 |
| White Pasta | 46 ± 10 | 40 ± 5 | 119 |
| Brown Pasta | 68 ± 10 | 40 ± 5 | 188 |
| Porridge | 60 ± 12 | 40 ± 4 | 209 |
| All-Bran | 40 ± 7 | 32 ± 4 | 151 |
| Eggs | 42 ± 16 | 31 ± 6 | 150 |
| Peanuts | 12 ± 4 | 20 ± 5 | 84 |
Below is a table of the average food catergories:
| Smarter Health and Fitness Insulin Index Analysis | |||
|---|---|---|---|
| Food | Glucose Score | Insulin Score | Satiety Score |
| Snack/confectionary | 65 ± 6 | 89 ± 7 | 100 |
| Bakery Product | 77 ± 7 | 83 ± 5 | 85.4 |
| Carbohydrate-rich | 88 ± 6 | 74 ± 8 | 158 |
| All | 68 ± 12 | 72 ± 9.5 | 136 |
| Fruit | 61 ± 5 | 71 ± 3 | 170 |
| Protein-rich | 54 ± 7 | 61 ± 7 | 166 |
| Cereal | 59 ± 3 | 57 ± 3 | 134 |
Summary
Carbohydrates are used as a fuel for your body and can be separated into two groups; simple and complex. In general complex carbohydrates release glucose into the blood slower than simple carbohydrates, thus maintaining more regular insulin levels, leading to less glucose being stored as fat.
However due to the ambiguity and exceptions to the simple/complex carbohydrate effects (some simple carbohydrates release glucose into the blood slower than some complex), it is more accurate to use the Glycaemic Index to decide which foods to eat.
The Glycaemic Index ranks food based on the speed of release of glucose into the blood, and a lower GI food release glucose at a slower and steadier rate. This can prevent mood swings and help maintain energy levels.
An even more accurate way to measure the insulin response to food is the Insulin Index that directly measures the insulin changes, something the Glycaemic Index and Glycaemic Load don't do. Though it is important to remember that it is based on 239 calorie portions and not regular serving sizes.
