Obesity has become an epidemic in the United States, with one-third of American adults classified as obese, according to the Centers for Disease Control and Prevention. In general terms, obesity occurs when a person consumes more calories each day than his body uses. However, in addition to calories, the type of food consumed determines how the body processes it, which affects the storage of the energy and therefore obesity. Where foods lie on the glycemic index also determines their likelihood of contributing to obesity.
Glycemic Index
Traditionally, nutritionists classified carbohydrates as either simple, meaning composed of one or two simple sugars, or complex, containing long chains of simple sugars. This simplistic classification system failed to fully predict the insulin and glucose response in the body. Therefore, in 1981, scientists developed the glycemic index to rank carbohydrates by their potential to raise blood glucose. The insulin response and the level of glucose in the blood affect the use and storage of energy, which affect obesity.
Glycemic Scale
Where a food lies on the glycemic index scale can help determine that food's ability to induce either weight gain or weight loss. Foods with a glycemic index of 55 or less are considered low-glycemic foods, according to the Calorie Control Council. Those ranging from 56 to 69, such as whole-wheat products and brown rice, are medium-glycemic foods. High-glycemic foods include those with an index number of 70 to 99.
High-Glycemic Effects
High-glycemic foods cause a more rapid increase in blood-sugar levels than low-glycemic foods, as described by the Linus Pauling Institute. The spike in blood-sugar levels triggers the pancreas to release large amounts of insulin -- the hormone that helps glucose move from the blood into the cells to be used as energy. Because the insulin clears the glucose from the blood, the glucose level sharply decreases a few hours after you have eaten the high-glycemic foods. This spiking effect is more likely to contribute to overeating.
Low-Glycemic Effects
Low-glycemic foods trigger only a moderate increase in blood sugar, inducing a normal insulin response. Therefore, low-glycemic foods help the body sustain the sugar levels for longer periods of time, promoting a feeling of fullness.
Effects on Obesity
Because low-glycemic foods help sustain a feeling of fullness for longer, they delay the return of hunger. Several small studies conducted on the effect of high- and low-glycemic foods on weight loss and weight gain found low-glycemic diets result in more weight and fat loss that high-glycemic diets, according to the Linus Pauling Institute. Low-glycemic foods may also help promote long-term weight loss.
