Most of us get at about 50 percent of our energy from the carbohydrates in our food. But what are they and what is the difference between carbs and sugar? And how do carbohydrates affect our efforts to control or reverse our diabetes?
In order to control your blood glucose levels and/or reverse your diabetes, you need to eat a diet that, among other things, is low in sugar.
Sugar molecules come in various combinations and guises collectively known as carbohydrates.
What are carbohydrates?
Carbohydrates (also known as saccharides) are chemical compounds that are made up of oxygen, hydrogen and carbon. They are one of the three major components or macro-nutrients of all food. The other two are proteins and fats.
There are four main types of carbohydrates. These are classified according to the number of sugar molecules they contain:
- Monosaccharides, such as glucose and fructose, contain only one sugar molecule.
- Disaccharides, such as sucrose and lactose, contain two sugar molecules.
- Oligosaccharides, found in many vegetables, are short chains of monosaccharides.
- Polysaccharides, such as starch and glycogen, are long chains of sugars.
The first two classes are known as simple carbohydrates, the second two as complex carbohydrates.
In the language of diets, however, the definitions are less strict. For nutritionists, the term carbohydrate refers either to any food (such as cereals, bread, and pasta) that is especially rich in starch (a complex carbohydrate), or to the simple carbohydrates (such as sugar) that are found in sweets (candies), jams, and desserts.
Sugar itself is the dietician’s term for monosaccharides and disaccharides, the simple carbohydrates. The names of these saccharides very often end in -ose, so they are fairly easy to recognise.
For example, grape sugar is glucose (a monosaccharide), cane sugar is sucrose (a disaccharide), and milk sugar is lactose (another disaccharide).
What are carbohydrates used for?
Carbohydrates are the most common sources of energy for the human body. Even the brain normally relies upon glucose for its energy.
However—and here’s the rub in our era of food plenty—if you eat more than you need, the excess carbs are changed into fat and stored around you body.
Different types of carbs are used for differing purposes by your body.
Monosaccharides are the major source of fuel for metabolism, the vital biochemical reactions (such as digestion) that occur in your body. They are used both as a source of energy (glucose being the most important) and in biosynthesis (the creation of more complex compounds such as cells from simpler forms).
Polysaccharides are used for the storage of energy (eg, as starch and glycogen), and as structural components (eg, cellulose in plants).
When the monosaccharides you ingest are not needed immediately they are usually converted into glycogen, a polysaccharide, in the cells of your muscles and liver where they are also stored.
Later, when energy is needed, muscle glycogen is converted into glucose in the muscle cells where it is used and liver glycogen is changed into glucose for use throughout the body.
Glycogen, however, only functions as a secondary store of energy.
The primary way you store energy long-term is in the form of body fat, which is formed once you have plenty of glycogen. Your excess glucose is converted into fatty acids. The fatty acids are then changed into body fat (aka blubber).
As you can see, eating too many carbs leads to weight gain, which can only worsen your diabetes. It is the reason why so many diets to lose weight rely on reducing the intake of carbohydrates, ie they are low-carb diets.
Effects of carbs on blood glucose
Your digestive system breaks down carbohydrates from food into glucose for energy. The glucose is released into your bloodstream and travels around your body, replenishing your muscle cells with the fuel they need to function.
Simple carbs have only one or two sugars, so they are digested quickly, making your blood glucose rise rapidly to a high peak, which is what diabetics need to avoid.
Examples of simple carbs include the sugars found in fruits and milk, the added sugars in processed foods, and table sugar.
Complex carbs contain three or more sugars, so these take longer to digest and thus they cause a less rapid rise in blood glucose and a lower peak.
Examples of complex carbs include the fibre in spinach, watercress, buckwheat, barley, wild or brown rice, beans, and some fruits.
As you can see, different foods cause quicker or slower rises in blood glucose depending on whether they contain simple or complex carbohydrates.
Other factors, such as cooking, can also cause blood glucose to rise quicker or slower. Pasta that has been well cooked, for example, will cause blood glucose to rise quickly, whereas as if it has been cooked al-dente the rise will slower.
The glycemic index (GI) ranks various foods based on how quickly they raise blood glucose, irrespective of the cause. It’s a useful guide for planning meals to beat your diabetes.
Lentils, green beans, broccoli, spinach, plums, yogurt, and brown rice are low on the list of GI values, ie they are digested slowly and raise blood glucose at a slower rate than items with higher GI values such as baked potatoes, white rice, white bread and watermelon.
Choosing the right carbs to eat
It’s important for people with diabetes to keep their blood glucose levels under control. This means limiting the amount of sugar you ingest with your food and ensuring that you try to eat foods that have low GI values.
To do this, you need to read food labels to find out how much sugar and other carbohydrates there are in particular food items.
For solid and semi-solid foods, the ‘nutrition’ section on the label will show a figure in grams for ‘total carbohydrate’. This total is usually broken down into ‘starch’, ‘sugars’ and ‘dietary fibre’.
Note that sugars include the natural sugars found in fruit and milk products as well as added sugars.
Added sugars are sugars that have been added during the production of processed foods in order to preserve the food or enhance (sweeten) the flavour. Being simple carbohydrates, they will raise your blood glucose rapidly.
Thus, to control your diabetes, you need to avoid added sugar or at least limit the amount you eat as much as you can.
Nearly all soft drinks, biscuits (cookies), and cakes contain added sugars. But you will also find added in yogurts, cereals and a wide range of other foods.
The problem, when you are trying to avoid added sugars, is that these sugars are not shown separately in the nutrition section of food labels. Thus, to avoid added sugars, you need to learn how to recognise them in the ingredient lists.
This is easy, as the names of many of these sugars end in -ose.
Examples include dextrose, sucrose, maltose and high fructose corn syrup, and if you see anything ending in -ose under ‘ingredients’ you can be pretty sure that the foodstuff contains added sugar.
Carbs and Nutrition
The amount of energy delivered by a gram of carbohydrate varies between simple and complex carbs.
Simple sugars yield 3.87 calories of energy per gram, while for complex carbohydrates the figure varies from 3.57 to 4.12 calories per gram.
Although carbs are the most important source of energy for humans, you can live without eating carbohydrates. This is because the human body can change proteins and fats into carbs.
Indeed people in some cultures eat food containing very little carbohydrate, yet seem quite healthy.
Whether severely restricting your intake of carbohydrate will have negative effects on your health is an issue that, so far, has not been studied extensively.
However in inadequate intake of dietary fibre – indigestible carbohydrates which are not a source of energy – can be bad for your health.
Fibre enhances digestion, among other benefits, and any diet to beat your diabetes must be high in fibre.
Research indicates that North Americans get about 40% to 60% of their energy from carbohydrates.
However, taking the risks of heart disease and obesity into account, the Institute of Medicine in the USA recommends that North American adults should be getting between 45% and 65% of their energy from carbohydrates.
By contrast, the two UN bodies concerned with food and health, the Food and Agriculture Organization (FAO) and the World Health Organization (WHO), jointly recommend that national dietary guidelines should set a goal of 55 to 75% of total energy from all carbohydrates, but with only 10% coming directly from sugars (simple carbohydrates).
These recommendations differ significantly and I don’t know why. Nor do I know which it would be better to follow.
A low-sugar diet
Some people like to control their diabetes by aiming for 45 to 60 grams of carbs per meal. Reading food labels can give you a good idea as to how many carbs there are in any particular dish. Several foods, however, do not have labels and so you may have to guess at the amount of carbohydrates they will deliver.
This is not too difficult. Suppose you want to eat a plain turkey sandwich with a half cup of fruit. The two slices of bread will together deliver about 30 grams of carbohydrate. The fruit will contain about 15 grams, giving a total for the meal of roughly 45 grams of carbs.
But to beat your diabetes, you really need to concentrate on lowering the sugar you ingest, not the total carbohydrates. Sugars, simple carbs, are the relevant carbohydrates for reversing diabetes.
To ensure that your diet is low in sugar, focus on a variety of vegetables, especially non-starchy vegetables such as leafy greens.
Cooked, non-starchy vegetables such as eggplant, okra or beets have only about 5 grams of carbs per half cup.
A diet with at least 3 to 5 servings of vegetables a day will help you lose weight and control your blood glucose.
There’s no need to avoid fruit just because you have diabetes. For example, a small peach or 1 cup of diced melon should come out at less than 15 grams of carbs.
Dried fruit is also OK, as long as you keep limit your intake to about one-third of the amount you would eat of the fresh fruit.
The trick is to go easy on foods that are high in sugar and have relatively high GI values. Foods with high levels of simple carbohydrates are usually highly processed or refined foods made from plants.
These include sweets, cookies and candy, table sugar, honey, soft drinks, breads and crackers made from refined grains, jams and fruit products, potatoes, pastas and breakfast cereals.
Instead of these foods, choose whole grains and other unrefined foods such as beans, tubers, brown rice, couscous, and unrefined fruit. There’s lots of delicious food out there that is low in sugar and can help you reverse your diabetes.