Two sodas a day could lead to 21-pound weight gain in one year
2/13/2003 10:21 AM
By: Karen Erickson, UNC Health Care
With over half of Americans overweight, more than 25 percent obese, and no end in sight to these rising trends, the search for answers continues. What experts know is that there is no one cause for the obesity epidemic.
Weight is a balance of calories consumed with calories expended and several factors contribute to the imbalance that causes weight gain. The kinds of foods we eat may not only cause us to gain weight, but also may contribute to the metabolic irregularities, such as insulin resistance and hyperlipidemia, that are associated with obesity.
Can fructose be to blame? Fructose is a sugar that is found naturally in fruits and vegetables and is added to foods in the forms of sucrose and high fructose corn syrup (HFCS). The production of these added sweeteners, found in soft drinks, breakfast cereals, baked goods, condiments and prepared desserts, has risen sharply over the past 20 years.
Not surprisingly, consumption of the foods in which sucrose and HFCS are found, especially soft drinks, has sharply risen as well. In the 1950s, the average size soft drink was 6 ½ ounces. Today, the average 20-ounce soft drink is dwarfed by the availability of “super size” and “double gulp” portions of up to 64 ounces.
In 1998, U.S. soft drink consumption was 42 gallons per capita per year, up from 23 gallons in 1970. Can soda really be the culprit? While considerable debate exits, there is at least some evidence that it plays a role.
Added fructose in the diet can contribute to weight gain. Just two 12-ounce sodas can provide an additional 200 calories a day. In studies, individuals who are given soda sweetened with HFCS end up consuming more calories and gaining more weight compared to individuals who drink diet soda. The individuals who drank the sweetened soda did not compensate for the extra calories they were consuming by reducing intake from other sources.
Over a year, an extra 200 calories a day could result in a 21-pound weight gain. This lack of compensation for the extra calories may be a result of the way the body processes fructose.
Normally, when sugar is consumed and absorbed, the body produces insulin. Insulin is necessary to allow the sugar into the body’s cells. In response to insulin, the body also produces a hormone called leptin, which signals the body to limit food intake and increase energy expenditure.
However, fructose does not cause the body to release insulin. With large doses of fructose, the body will take in a significant amount of calories but will not have the normal response to limit calories taken in and increase calories burned. Over a period of time, this could lead to weight gain.
In low doses, fructose can be helpful in improving blood sugar control in diabetics. However, in large doses such as those found in sweetened soft drinks, fructose (compared to glucose) contributes to greater fat production. This can result in hyperlipidemia, a risk factor for heart disease. Individuals with already existing hyperlipidemia or type 2 diabetes are at greater risk.
So what is the take-home message concerning fructose? Limit intake of soft drinks. They provide empty calories and may contribute to unwanted weight gain. In addition, they are devoid of other nutrients necessary for good health.
Instead, enjoy at least five servings of fruits and vegetables a day, quench thirst with water and consume beverages that provide valuable nutrients such as calcium in non- or low-fat milk. Sugars from complex carbohydrates should be consumed in amounts as recommended by the Food Guide Pyramid, with an emphasis on whole grain sources.
Karen Erickson, MPH, is managing director of the Clinical Nutrition Research Center at the University of North Carolina at Chapel Hill.
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