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LOSE WEIGHT:  How the Glycemic Index can Help?

By Dr. Keith E. Lewis
June 26, 2008


One of the most difficult and challenging problems our patients experience when dieting or trying to lose weight is that they feel hungry all the time or they feel deprived or they do not have any energy. This, however, does not have to be the case, especially when implementing a lower GI or GL diet.

Carbohydrates after all are natural appetite "satisfiers". Gram for gram, carbohydrates, and those with a low GI are some of the most filling foods you can eat, as well as hunger preventers for the longest amount of time. In the past, it was believed that protein, fat, and carbohydrate foods taken in equal quantities satisfied our appetite equally.  We now know from recent research that satiety capacity, the degree to which foods make us feel full, of these nutrients is not equal. Fatty foods in particular have only a weak affect on satisfying appetite relative to the number of calories they provide. This has been demonstrated clearly in experimental situations where patients are asked to eat until their appetite is satisfied. They over-consume calories if the foods they are offered are high in fat.  When high carbohydrate, low-fat foods are offered, they consume fewer calories when given the opportunity to eat till satisfied, so carbohydrate foods are the best in terms of satisfaction without over-satisfying your calorie requirement. Low glycemic foods fill you up and keep you satisfied longer.

In several studies, after energy density, the second best predictor of satiety is the food's glycemic index ranking. The lower glycemic index values, the more the food satisfied people and left them feeling less hungry. As a matter of fact, there were over 15 studies that confirm low GI foods were able to suppress hunger for longer than high GI foods. 

There were several reasons for this:

    1)  Low GI foods remain longer in the small intestine, triggering receptors that tell the brain there is food still in the           gut to be digested. 

    2)  Low glycemic index foods may be more satisfying simply because they are often less energy-dense than their              higher GI counterparts. 

The natural high fiber content of many low GI foods increases their bulk without increasing their energy content. 

Stress hormone such as adrenalin and cortisol are released when glucose levels rebound after a high glycemic index food. Both hormones tend to stimulate appetite. High glycemic index food may stimulate hunger because of the rapid rise and fall in blood glucose levels. This appears to stimulate counterregulatory hormonal responses to reverse this decline; result, you feel hungry.

Even when the calorie intake is the same, people eating low GI foods may lose more weight than those eating high GI foods. In one particular study where the amount of calories, fat, protein, carbohydrate, and fiber were consistent, the only variable were low glycemic index foods and high glycemic index foods. The low glycemic group lost an average of 4½ pounds more over a period of 12 weeks than those ingesting high glycemic foods over the same time period. What we can conclude from this is that low GI foods resulted in lower levels of insulin circulating in the blood stream. Insulin as you may or may not know is a hormone that is not only involved in regulating blood sugar levels, it also plays a key part in when and how we store fat.

High levels of insulin often exist in obese people, in those with high blood fat levels either cholesterol or triglyceride, and in those with heart disease. This study suggested that low insulin response that is associated with low glycemic index foods help the body to burn more fat rather than to store it.

The other reasons why low GI diets seem to be effective are as follows:  In many people when they began dieting, there was a drastic drop in metabolic rate because of reduced food intake. One study found that the metabolic rate dropped less after one week on a low GI diet than on any other conventional high carbohydrate diet.  The same study suggested that the low GI diet helped better preserve lean muscle mass, which could explain why metabolic rate was higher.

At this point, I would like to deviate and discuss insulin and the organ that produces insulin, the pancreas. The pancreas is one of the most important organs in our body. It is located near the stomach. Its primary job duty is to produce insulin. Secondarily, however, it does produce another hormone called glucagon, which is affected by protein ingestion. Carbohydrates stimulate the secretion of insulin more than any other component of food. The slow absorption of carbohydrates in our food means that the pancreas does not have to work as hard and needs to produce less insulin. This is good because if the pancreas is stimulated over a prolonged period of time, it may actually become exhausted and not produce enough insulin and diabetes may develop. Even without diabetes, high insulin levels are undesirable because they increase the risk of heart disease. The relationship with increased insulin production and heart disease is inflammation.  Increase or excessive production of insulin does result in inflammation of the blood vessels and all organ systems innervated by those blood vessels. Our bodies need insulin for carbohydrate metabolism, but it has profound effect on the development of many diseases.

Many experts now believe high insulin levels are one of the key factors responsible for heart disease and hypertension, as I previously stated. Insulin influences the way we metabolize foods, determines whether we burn fat or carbohydrate to meet our energy needs, and ultimately determining whether we store fat in our bodies. Insulin production and digestion and food processing are more important now than ever to understand. Hundreds of years ago, our ancestors did not deal with these issues because we did not overly process our foods and as we have previously stated in this article and other articles. The over-processing of foods ultimately results in an overproduction of insulin to help manage and control fluctuating blood glucose levels.

In summary, evaluating and measuring the glycemic index, as well as the glycemic load would better enable us to control our blood insulin levels. Also, by better managing our blood glucose levels, we are able to manipulate and reduce the amount of excessive fat accumulation in our body by maintaining a more stabilized blood glucose level. Excess blood glucose in our body is converted to fat. The storage form of that fat is triglycerides. 

Again, with glycemic index foods it is very important that we understand the concept, so we might better mange blood sugar metabolism.

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