When exercise is paired with a high-carbohydrate diet, does the combination lead to greater weight loss, compared with a situation in which exercise is coupled with diets which are not so heavily biased toward carbs? That's a question which has intrigued weight-loss scientist for some time. At first glance, one might think that high-carb eating plans would offer no unique advantages, compared with lower levels of carbohydrate consumption. Do Carbs Curb Appetite

After all, it is the total number of ingested calories which is the important factor in weight loss, not the macronutrient composition of those calories, right? Eating 1600 daily calories of carbs plus 400 calories of fat (for a total of 2000 calories) and jogging five miles for one's exercise should have approximately the same effect on weight as consuming 1000 calories of carbs and 1000 calories of fat (also 2000 calories) and covering the five miles, at least in theory.

However, proponents of the carb-exercise connection cite several studies which have shown that diets high in carbohydrate tend to suppress appetite and overall energy intake (1,2,&3). The mechanism underlying this suppression is not known, but one hypothesis is that the higher circulating levels of insulin associated with lofty carbohydrate intakes tend to keep the feelings of hunger under wraps (insulin produces a well-known "anorexic" effect). Of course, such thinking is "anti-Atkins" and "anti-Zone", but it has experimental support. If you would like to read more of this article (Vol.1-6), simply enter carbs, in the "search archives" box, or enter any subject you wish to learn more about.

Whenever you eat, the quantity of sugar (glucose) in your blood rises. The extent of this sugary ascent depends on what you eat and how much you ingest, and it is also a function of the amount of insulin which your pancreas produces in response to the eating (insulin is a hormone which lowers glucose levels). What does this have to do with losing weight? Some foods initiate gut-wrenching climbs in blood glucose, while others nudge glucose upward in inchmeal fashion. LOW-GI FOODS

Classic "glucose spikers" include glucose itself, table sugar (sucrose), and white bread, while the foods which make glucose react more lazily are vegetables, beans, lentils, wholegrain foods, and many fruits. The potential problem with the sugar snowballers is that the gargantuan gain in glucose can cause a massive insulin inflow, leading to a sudden, precipitous fall in blood-sugar levels. This steep fall can be associated with the onset of intense hunger, and thus overeating. In a recent study, overweight boys who consumed breakfasts which contained easily digestible carbohydrates designed to expand blood glucose rapidly snacked almost twice as much during the morning hours, compared with young men who took in a breakfast with the same number of calories but a less-dramatic impact on blood sugar (1).

Scientists interested in human nutrition have been able to quantify the effects of various foods on blood glucose by creating a gauge called the glycemic index. Foods with a high glycemic index (GI) produce quick, rapid rises in blood sugar, while eatables with low GI lead to slower, lighter, longer, blood-glucose enhancements. The process of establishing a particular food's GI is fairly elaborate: Each food must be tested on a number of subjects, and each subject must be examined several times.

Every subject to be tested undergoes an overnight fast and then consumes a specific food, the overall quanity of which has been adjusted so that it provides exactly 50 grams of carbohydrate. Over the ensuing two hours, blood samples are taken from the subject to determine changes in glucose concentration. The glycemic index for that food for that individual is then determined by dividing the blood-sugar response to the test food (actually, the area under the "curve" created by graphing blood sugar as a function of time) by the subject's blood-sugar response to either 50 grams of pure glucose or 50 grams of white bread and then multiplying by 100. If the calculated GI turns out to be 100, for example, the tested food produces exactly the same blood-sugar response as glucose or white bread (the areas under the curve are the same); if the GI is above 100, the glucose response is even greater in magnitude. LOW-GI FOODS

Note that there is individual variation between people in terms of how they react to specific foods, so the glycemic indices you see published in GI tables are usually the average from about 10 tested subjects. Of course, individuals suffering from diabetes have used glycemic index as a tool for decades, as they try to "smooth out" changes in blood-sugar levels. Diabetics tend to choose low-GI foods because they wnat to avoid unmanageable uprise in blood sugar, but they also may keep glucose tablets (with a high GI) handy in case blood sugar drops too low.

Today, however, GI is also thought to be a useful dieting tool many weight-loss experts and individuals seeking to lose some weight. To put it simply, the idea is that foods with a low glycemic index (GI) should produce small but steady and reliable upswings in blood sugar over time, thus delaying hunger, while comestibles with a lofty GI should provide the "roller-coaster ride" of blood sugar, insulin, and appetite mentioned above. In theory, low-GI foods should be more conducive to weight loss, and several well- respected researchers have advocated low-GI diets for the prevention of weight gain and obesity (2, 3, &4). Several popular diets emphasize the low-GI-is-good theme.

For example, The Zone Diet takes into account the GI of various foods, as does the popular new Glucose Revolution Diet. What is sometimes forgotten is that the traditional Mediterranean Diet, which focuses on the consumption of olive oil, nuts, fruits, vegetables, and whole grain, is also a low-GI eating plan. The reason for this is that the relatively high content of (healthy) fat in the Mediterranean plans slows down carbohydrate absoprtion across the wall of the small intestine, tempering rises in blood sugar. As you might expect, the Mediterranean-style diet is noted for its hunger-soothing qualities. LOW-GI FOODS

To learn more about Eating Low-GI foods(the full article can be read by purchasing Vol.1 Issue 3) and many more weight-loss related topics. Or enter any subject you wish to learn more about.