Nutrition: Sugar

Not all kinds of sugar are the same. Refined white sugar has been labelled as white death, but really, it isn't the worst kind.

Our body cells need energy to operate, and that energy is provided in the bloodstream as the chemical glucose, a simple sugar molecule. Whenever the level of glucose in our blood drops below a certain level, we feel hungry. If it drops lower, the body produces glucose from our stored fat. When that fat is gone, the body resorts to turning protein from our muscles and internal organs into glucose.

Burning body fat is how we lose weight when we diet. Burning internal organs is how we starve to death.

Normally, the glucose we need to live is provided in our food, usually as complex carbohydrates in the form of sugars and starches. Starches take a while to digest (converted into glucose), so they are excellent for providing energy for hours after eating. Sugars though can be digested quite quickly (dietary glucose require no digestion at all), so they are excellent for providing a quick energy boost.

Typically the sugars in food are not simple sugars but more complex molecules consisting of two simple sugars linked together. These molecules are digested (in this case cut into their two component simple sugars) by enzymes. Maltose, lactose, and sucrose are the three most common complex sugars.


is found in sprouting grains and is an excellent sugar for fermenting into beer and whisky. The enzyme maltase cuts maltose molecules into two glucose molecules, which are then immediately available for energy supply in the blood.


is found in milk. The enzyme lactase cuts lactose molecules into one glucose molecule and one one galactose molecule. The glucose is immediately available, while the galactose must be further digested before being converted into glucose. For babies, this means that the glucose satisfies the immediate hunger (stop crying), and the galactose prolongs the time until the next feeding is necessary (Some for now, some for later).


is the most common naturally occurring sugar in our food. The enzyme sucrase cuts sucrose molecules into one glucose molecule and one fructose molecule. (In some foods, this sugar has been predigested (inverted sugar). E.g. honey contains approximately equal amounts of glucose and fructose (the lumpy and runny parts when it starts to crystallize).) And just as lactose does for babies, the glucose provides immediate satisfaction while the fructose provides a longer-term energy supply. But unlike galactose, the conversion of fructose into glucose is not as simple.

Fructose requires several chemical conversions in the liver to be digested. It results in glyceride molecules that are converted to glucose only when needed. This on-demand supply is good for people with diabetes, since it avoids creating high levels of glucose in the blood. On the other hand, for non-diabetics this effect can be bad, as unused glycerides are stored as fat to meet long-term demand.

Traditionally, mothers tell their children not to eat candy or soda-pop at certain times because it will spoil your dinner. If they eat candy, the glucose quickly enters their bloodstreams and they no longer feel hungry. They then have little incentive to eat your vegetables.

Candy and soft-drinks used to be made with sucrose (table sugar) and sometimes glucose (corn syrup), but that is no longer the case. Now fructose (high-fructose corn syrup) is the main type of sugar used in many products (it's cheaper and sweeter). It provides the same calories as traditional recipes, but doesn't provide the immediate satisfaction of hunger (it no longer spoils dinner). Instead of a small drink or a couple of candies, now one needs a large drink and several candies and perhaps a bag of chips to make a snack feel worthwhile.

The food we eat isn't satisfying our hunger, we are eating more of it than we normally would, and the excess sugar is in a chemical form just waiting to be stored as body fat. For people that don't carefully monitor what they eat, fructose is a recipe for disaster.