Carbohydrates are one of the three main types of energy that your body is physically able to burn for fuel. The other two energy types are fats and alcohols. This is basic human construction.
The Carbohydrate is the easiest thing for your body to burn, so if your body has the choice of burning through that Ring Ding you ate or the fat on your thighs, it'll burn the Ring Ding (and probably add more extra fat to your thighs afterwards, too). On the other hand, if you eat fats or alcohols, your body has to first convert those things INTO carbohyrdates, and then use the carbohydrates for energy. So even if you eat more CALORIES on a fat-rich diet, you still lose more weight, because your body is doing extra work to use those fats. Living on an alcohol diet is not recommended for many reasons :)
There are two types of carbohydrates:
Simple Carbohydrates - Sugars
Sugars include the white table sugar stuff (sucrose) as well as fruit sugars (fructose), milk sugars (lactose) and so on. Sugar is SUPER easy for your body to use, so it doesn't have to do any work. It also spikes your body's blood sugar levels, causing huge mood swings. And when the sugar rush is gone (and all the excess sugar is packed into your tummy for storage as fat) then your body gets hungry immediately and craves more food. It is these swings and the easy-to-fat cycle that low carb diets are trying to break. Believe me, when Man was evolving, he did not have Yodels and chocolate-covered donuts hanging on his trees. The amount of sugar modern man eats - in everything from breakfast cereals to breads and TV dinners - is staggering.
Complex Carbohydrates - Starches
Starches are those rich carbohydrates found in bread, potatoes, pasta, french fries, and so on. Starches cause the exact same problems that sugars do. They spike your blood sugar levels, giving you a quick boost of energy, but setting you up for a big LOSS of energy once the spike is gone. You also feel hungry again after the spike because the blood sugar levels drop so drastically. Many foods such as Chinese food are cooked in very starch-rich sauces, which cause the hungry-shortly-afterwards issues.
Dietary Fiber
If you look at a nutrition panel on processed food, you'll see that Dietary Fiber is listed under the total carbohydrate listing. Fiber is a VERY healthy thing to eat and helps keep your digestion system regular. Eating fiber daily is very important to your health. Better yet - fiber does NOT impact your weight situation at all. Fiber doesn't turn into fat or energy - it just goes through your stomach and intestines, helping to keep it clean. So in short, fiber does NOT count as a carb.
Going low carb is NOT about avoiding vegetables at all!! It is about avoiding HIGH CARBOHYDRATES. So that means staying away from things like white bread, potatoes, pasta, candied yams, and the like. I'm not sure there is any dietician that would tell you that eating white bread IS healthy for you. Maybe things like potatoes were necessary for farmers in the 1700s who were out in the field working hard, who needed a supply of high-powered energy to get through the day. But for the normal person in the developed world, that high powered energy simply equates to thick thighs and a round stomach.
Effective Carbs vs Total Carbs
Lisa Shea's Library of Low Carb Books
