Fructose: The Weight-Gain Sugar
Obesity is an epidemic in America that now affects many millions of adults and children. Obesity is classified as having a body mass index (BMI) of greater than 30.
According to the CDC, the percentage of the population who are obese has steadily increased from 14% in 1960 to 35% in 2008. The percentage of kids ages 6-19 who are obese has risen from 5% in 1976 to almost 20% in 2008.
What could be causing this large increase in obesity over the past 50 years? In a study published in the American Journal of Clinical Nutrition*, data from the US Department of Agriculture was analyzed using food consumption tables. Between the years of 1970 and 1990, high fructose corn syrup (HCSF) consumption increased by more than 1000%! No other food came close to this increase. For many years, average fructose consumption was about 16-20 grams (3-4 tsp) daily, mostly from fresh fruits. Now the average person consumes 80-100 grams (16-20
tsp) of fructose. Not difficult to do the math.
What exactly is fructose? Fructose is a simple sugar that is found naturally in fruits and vegetables, cane sugar, honey, maple syrup, and agave syrup. It is usually found in combination with glucose, another simple sugar. There are fruits, such as apples and grapes, that naturally have higher concentrations of fructose, generally 60% fructose and 40% glucose, and are therefore commonly used as “natural” sweeteners. HFCS
is manufactured to be anywhere from 55-95% fructose, with the rest being glucose. Honey, maple, and agave all have higher fructose concentrations.
Why do we use fructose? Well fructose is the sweetest tasting sugar, even sweeter than glucose. And in the early 1970s, studies started reporting that the use of non-glucose sugars was better for diabetic patients. So it began that fructose, mostly as HFCS, was added to foods and
beverages as a sweetener.
How is fructose making me gain weight? Fructose is metabolized much differently than glucose. It is metabolized in the liver and produces either more glucose, or more fats in the form of triglycerides. When this happens, blood sugar (glucose) levels can further increase (which can eventually lead to insulin resistance), and fat levels increase. Fructose also does not stimulate production of leptin , a hormone that controls appetite. When your leptin level is high, this tells the body to stop eating. Without that message from leptin, your appetite doesn’t know to ease up. So if you drink a can of soda, not only will this not satisfy your hunger, but in the long run it can lead to a pattern of over-eating and high daily calorie consumption.
What is the take-away message? To fight obesity, decrease your sugar consumption, especially in the form of fructose from HFCS, fruit juices, sweetened beverages, and processed foods. Look at those labels, read those ingredients (and understand what they are!), eat fresh foods whenever possible, and drink lots of water or herbal tea (no calories). And if you eat a lot of sugar, you have to exercise to burn sugar, otherwise it all gets converted to fat!
Consumption of high-fructose corn syrup in beverages may play a role in the epidemic of obesity.
Bray GA, Nielsen SJ, Popkin BM.
Pennington Biomedical Research Center, Louisiana State University, Baton Rouge, LA 70808, USA.
Am J Clin Nutr. 2004 Oct;80(4):1090.
