Although obesity is not classified as a disease, it is associated with a variety of diseases and since it is a problem - or potential problem - for so many people, the role of sugar in its development and treatment needs to be looked at carefully.
Firstly, overweight, and later obesity, develop as a result of an imbalance between your energy intake (from food) and energy output (the energy used for daily living, including basic body functions and any exercise you do). When you take in more energy than you are using, the body stores the additional energy as body fat. The source of this extra energy is immaterial; it makes no difference where the additional kilojoules come from. In other words, it is not eating one particular food but rather eating too much overall that leads to weight gain. It is possible to put on weight by eating (or drinking) too much of anything.
In practice this would of course be extremely difficult in the case of bulky foods with a high moisture content - such as certain vegetables - simply because it would be difficult to eat enough of these foods to provide kilojoules in excess of your energy needs. By contrast, in the case of concentrated, energy-dense foods such as rich desserts, fried foods or chocolate, it is all too easy to eat enough to lead to an excessive energy intake. Sugar, being a carbohydrate, is not the worst offender in this respect - fat is a far more concentrated source of energy - and it has been said that sugar is often 'guilty by association' because many so-called 'fattening foods' are high in both fat and sugar. For example, in the case of chocolate, sugar contributes approximately 33°k of kilojoules, compared to the fat contribution of over 50%.
Studies have shown that fat people don't eat more sugar than lean people, neither do they have more of a sweet tooth. They do however tend to eat more fat. In the light of recent research this makes sense, since we now know that it is easier to become overweight by eating too much fat than by eating too much carbohydrate.
Fat vs sugar
There are several reasons why fat is a bigger culprit than sugar when it comes to the problem of overweight. To begin with, as mentioned above, fat is far more energy-dense than carbohydrate - a gram of fat provides 38 kilojoules, whereas a gram of carbohydrate provides only 17. Secondly, carbohydrate seems to have a so-called thermogenic' effect, that is, it pushes up the body's metabolic rate so that kilojoules are burnt up faster. Lastly, the process by which the body converts dietary fat into body fat is a very efficient one - only 3% of the kilojoules are lost along the way. By contrast, when the body converts dietary carbohydrate into body fat, 23% of the kilojoules are lost. In other words, when you eat carbohydrate, only 77% of the kilojoules from that food are available as energy for the body.
To prevent weight gain, therefore, the best diet to follow is one that is low in fat and high in carbohydrate. This does not mean a diet high in sugar - the recommended carbohydrates in this case are complex carbohydrates, or starches. You can, however, include a limited amount of simple carbohydrates or sugar in your diet without fear of becoming overweight, as long as the total energy value of the diet is in line with your energy needs. Remember, it is the balance between your energy intake and your energy output that counts, rather than the type of food you eat. People who burn up a lot of energy (through, say, regular exercise or even nervous tension) can therefore eat more of these foods without fear of gaining weight, than can those whose energy requirements are much lower.
Sugar and slimming
When it comes to weight reduction, however, sugar should be looked at more carefully. The basic principle of a slimming diet is to select foods that are high in nutritional value but low in energy, so that although your kilojoule intake is restricted, all your nutritional requirements are met. Sugar provides only energy, so it is the first thing that should be excluded from a slimming diet. Interestingly, though, there is a school of thought which suggests that from a psychological point of view, a small quantity of sugar may be included in a slimming diet to help prevent feelings of deprivation and resultant binges. This obviously depends on the individual - some people crave sweetness and provided they can limit their consumption of sweet foods to one 'treat' a day, it may not be necessary for them to eliminate sugar totally. Of course, if once you've opened a packet of sweets you can't stop until you've eaten the last one - or if you're one of the lucky ones who seldom craves `something sweet' - it would be simpler to cut out sugar completely!
