While current research has shown that people in general have reduced their consumption of fat, there are more alarming findings about sugar consumption. Obesity has now been declared a worldwide epidemic and statistical evidence suggests that obesity has more to do with sugar consumption than fat consumption.
We need a reasonable understanding of different sugars in order to make the right choices. As this may get a little too technical for some people, I have relegated a list of definitions to the end of this article.
Sugars of one type occur naturally in foods like fruits and vegetables. Processed sugars which have a different constitution are added to foods, fruit juices and other drinks as sweeteners in order to make the products more palatable. Herein lies the difference between what is good and what is bad.
We need to differentiate between sugars classified as monosaccharides and disaccharides and then we need to get familiar with the terms fructose, sucrose, glucose, lactoseand galactose. Then, there’s the role glucose vs. glycogen in our bodies. It gets complicated so let’s keep to the essentials.
Monosaccharides are the simplest form of sugar and include fructose, glucose and galactose.
Fructose occurs naturally in fruits, honey, berries and most root vegetables. Your consumption of the foods in which it occurs naturally is healthy. Other monosaccharides include glucose and galactose.
A U.S. survey reveals that about 9% of average caloric intake comes from fructose. Only one-third of this fructose comes from fruit, while the other two-thirds come from added refined sugars; this is where you will find a correlation between unhealthy sugar consumption and obesity.
Disaccharidesare carbohydrates that are created when two monosaccharides are joined. The best known disaccharides is sucrose, commonly known as table sugar, in which a fructose molecule is joined with a glucose molecule. Another common disaccharide is lactose, found only in milk, in which a glucose and a galactose molecule are combined.
Glucose is a sugar that our metabolism converts into energy. Our brain and other tissues require a constant supply of blood glucose to survive. Glucose, transported via the bloodstream, is the primary source of energy for the body’s cells; it is the prime metabolic fuel source for most organisms, from bacteria to humans.
Our body produces glucose when we digest the sugar and starch that are contained in carbohydrates. Such foods include rice, grains, pasta, potatoes, fruits and vegetables. Enzymes break down the starch and sugar into glucose which is absorbed into our bloodstream. The glucose combines with insulin and together they provide the energy for our muscles and brain.
It is vital to our health to keep glucose levels within a normal range. Because the energy originates from the foods we eat, our body has a mechanism for maintaining a normal range. This mechanism is seated in our liver which stores excess glucose as glycogen.
Glucose and glycogen
Our body absorbs glucose from the foods we eat and this may obviously occur irregularly. The glucose that the body does not use immediately is converted into glycogen.
Glycogen is a chain of glucose sub-units stored primarily in the liver and in our muscles. This glycogen is used to buffer our blood glucose level. For example, our muscles use the glycogen stored in the liver for energy during strenuous exercise.
What is important in our pursuit of fat loss is the fact that any glucose in excess of the needs for energy and storage as glycogen is converted to fat. This is the underlying cause for the common argument that claims as follows:
- Fruit contains fructose.
- Fructose turns to fat.
- If you want to lose fat, do not eat fruit.
This argument is essentially false because it ignores the way in which our body metabolizes fructose.
Fructose and glycogen
Fructose can stimulate lipogenesis which means the accumulation and storage of fat. However, fructose is primarily stored in our liver as glycogen. The liver can comfortably handle a daily intake of 50 grams of fructose without storing any extra fat and it can store 100 grams of glycogen.
This is an important observation. A normal piece of fresh fruit contains approximately 6-7 grams of fructose so you would need to eat more than 5-7 pieces of fruit in a day to absorb 50 g. In contrast, you can very easily absorb more than 50 g of fructose by drinking a lot of carbonated soft drinks, or drinks sweetened with fructose corn syrup.
High fructose corn syrup (HFCS) consumption has increased dramatically and is now a main contributor to obesity. You need to understand the following misconceptions:
- People confuse HFCS with fructose that occurs naturally in fresh fruit.
- The entire weight of a piece of fruit is not made up of fructose; most of the weight is fiber.
You will suffer no ill effects from eating several pieces of fresh fruit on a daily basis. What you need to steer away from is HFCS consumption and processed sugars added as sweeteners to food products and drinks.
Fructose, or fruit sugar, is one of three dietary monosaccharides, the other two being glucose and galactose. All three are absorbed into our blood stream during digestion.
Fructose is a naturally occurring sugar, typically found in fruits, honey, berries and most root vegetables. It is the most water-soluble of all sugars. In plants, fructose may exist as a monosaccharide and/or a component of sucrose. in scientific terms called a disaccharide.
Commercially, fructose is derived from sugar cane, sugar beets and corn. Derived from these sources, it comes in three forms:
- Crystalline fructoseis the monosaccharide and has high purity when it has been dried and ground.
- High-fructose corn syrup (HFCS) is a mixture of glucose and fructose.
- Sucrose (see definition below) is commonly added to foods, fruit juices and other drinks as a taste enhancement.
Sucrose is a complex carbohydrate that exists naturally in fruits and vegetables and occurs in greatest quantities in sugar cane and sugar beets. The food industry separates the sugar from these plants to produce table sugar and sweeteners which are added to foods, fruit juices and other drinks.
During digestion, sucrose is broken down into its constituent monosaccharides, glucose and fructose. The glucose and fructose molecules are absorbed into our blood stream and causes a rapid rise in blood glucose levels. This can cause problems for people who suffer from hypoglycemia or diabetes.
This is a simple sugar found in lactose that is less sweet than glucose (table sugar). It is a monosaccharide (see above) that comes mainly from milk and milk products. Galactose is metabolized primarily in our liver into glucose 1-phosphate.
A sugar formed by galactose and glucose found mainly in milk where it occurs at 2-8% by weight. When we consume milk, an enzyme called lactase breaks down lactose into glucose and galactose. Because of hereditary factors of food sources, European people are generally far more tolerant of lactose than people from Africa and Asia. People who are intolerant to lactose may suffer bloating and flatulence when they consume milk products.