CARBOHYDRATE INFO

Simple carbohydrates such as sugar in fruit (fructose) or cookies (sucrose) have long been used by athletes as insta-fuel for hardworking muscles. But new research shows that a prevalent form of manufactured sugar, which is found in everything from energy bars to sports drinks, may not be so effective after all.

High -fructose corn syrup (HFCS) gives you an overdose of the type of sugar that your body is not set up to process in large armounts; fructose. Formed by chemically rearranging cornstarch molecules into fructose, HFCS is processed by the muscles but not by the liver (unlike glucose, which can be processe by both). Unless you are exercising to excess, the HFCS in a 32-ounce sports drink or a large soft drink yields far more fructose than your muscles can handle. The leftovers, researchers suspsect, are absorbed into fat cells. And since fructose does not stimulate insulin and leptin secretion, which cue the central nervous system to register a feeling of fullness, it can also lead to overeating and overdrinking.

HFCS is highly inefficient for althletes and has calories but no nutrients, and the stress of processing it will make your recovery longer. Use the tips below to maximize your sugar high:

Energy Bars--Watch out for energy bars, granola bars and breakfast bars; most are loaded with HFCS. In general, althetes should get 10% of their daily calories from sugar. Try HFCS-free energy bars such as Clif Bar (sweetened with organic brown rice syrup), Kashi GoLean (sweetened with evaporated cane juice), and ProBar (sweetened with brown rice syrup, barley malt syrup, and organic evaporated cane juice).

Breakfast Cereals--Even familiar whole-grain brands such as Kellogg's Smart Start, Special K, Fruit Harvest, Complete Wheat Bran Flakes, and Frosted Mini-Wheats are loaded with HFCS. Instead, opt for Trader Joe's Frosted Shredded Bite Size Wheats (sweetened with regular sugar). You can also try Kashi Organic Proomise, which uses organic evaporated cane juice, and Barbara's shredded Oats, with unsulfured molasses.

Fluids--Cut down on drinks that aren't made with 100% fruit juice. Other HFCS drinks include some energy-drink brands (All-Sport, Powerade, Rockstar) and so do nearly all nondiet soft drinks, nectars and teas. Stick with Gatorade which is HFCS free. Diet sodas don't have it; they use artificial sweeteners such as aspartame instead.

Cut Out Fructose and Lose Weight

Fructose consumption in the US has been on the rise since the early 1970's. Americans currently consume just less than 51 pounds of fructose per year on average, an increase of ~8 lbs. per year over the past 4 decades.

Most fructose is consumed in the form of high-fructose corn syrup (HFCS), which has since replaced sucrose as the primary sweetener in manufacturing. HFCS is 55% fructose and 45% glucose, which is similar to the breakdown of sugars in fruit. Some argue that because the rise in fructose consumption parallels the increase in overweight and obesity, fructose is a major reason for the current obesity epidemic.

Researchers at the University of Texas, Southwestern have recently discovered a link between fructose and body fat that might confirm that argument in part. Six participants completed three protocols to evaluate the effects of fructose: a breakfast drink equal to 100% glucose; a beverage 50% glucose and 50% fructose; and one drink 25% glucose and 75% fructose. Each beverage contained exactly 85g of sugar. All participants ate a normal lunch approximately four hours following ingesting of the sugary beverage. Glucose and insulin peaked higher in the 100% glucose beverage. However, sugar was converted to body fat at a greater rate in both fructose-containing beverages when compared to pure glucose. In fact, the rate was double, but not significantly different between the two fructose-containing beverages. Moreover, when a fructose-containing beverage was ingested before lunch more fat was stored from the lunch meal than when pure glucose was consumed. Following lunch, serum triglycerides were up to 29% greater and Triglyceride-rich lipoprotein up to 200% greater following the fructose-containing beverages.

Although this study might make you think twice about having that banana, remember that there are many potential factors that contribute to obesity. Excessive fructose consumption would have to co-exist with excessive calorie intake to increase the rate of weight gain.

Parks, E.J., et al (2008) Dietary Sugars Stimulate Fatty Acid Synthesis in Adults. Journal of Nutrition. 138:1039-1046