Did you know, much like the average American, many bodybuilders, powerlifters, and other fitness athletes are consuming fructose in large quantities and don’t even realize it? Unfortunately, whether you’re aware or not, research shows this practice will result in a lower metabolic rate, insulin insensitivity, less fat burning, increased triglycerides and an increase in visceral belly fat. Not a good combo if your goal is to be healthy and lean.
The “fat carb”, as it’s been called by scientists, went from 13% of total caloric sweeteners in the U.S. to 50% in 1985. In 2009 fructose made up 76% of all caloric sweeteners, and is currently in tens of thousands of products including nutritional supplements.(1) The next time you're in the grocery store, check out some nutrition labels; the products you thought were healthy are not only stalling your progress, there trashing your body. We’ve been led to believe that fructose from high fructose corn syrup (HFCS) is a naturally occurring sugar and our bodies can’t tell the difference between it and other forms of sugar. Nothing could be further from the truth.
Researchers in a double-blind study compared the effects of eating a diet comprised of glucose or fructose sweetened beverages that provided 25 percent of the subject’s energy requirements for 10 weeks. Both groups gained a similar percentage of weight and body fat, but the glucose group gained subcutaneous fat, while the fructose group gained visceral abdominal fat. Subcutaneous fat is the fat you can grab just under the skin. Visceral fat, however, is not found under the skin. It surrounds the internal organs inside the abdominal cavity. Increased abdominal fat, especially visceral fat is concerning because it produces hormones and other substances that profoundly affect our health in negative ways. (2)
More-over the fructose group had a significant decrease in lipolysis (fat burning) and decreased insulin sensitivity and glucose tolerance. The glucose group had little change in lipolysis, insulin sensitivity, and glucose tolerance. Researchers also repeated the findings in a study by researchers from the University of California, Davis demonstrating the consumption of fructose slowed participants metabolic rates. (2,3)
If that doesn’t sound like a recipe for disaster, I don’t know what does. But wait, it gets better.
A study published in the Journal of Nutrition was performed to determine the magnitude by which consumption of fructose would stimulate lipogenesis (fat formation). The subjects consumed a drink containing 85 grams of sugars in a random blinded order. The drinks included either 100:0 glucose, 50:50 glucose to fructose or 25:75 glucose to fructose. Researchers concluded that when the subjects consumed fructose, lipogenesis was 200 percent greater than when it was absent. (4) Are you starting to see how crucial it is to read food labels and avoid products that contain fructose carefully?
The problem is our bodies metabolize fructose differently than glucose. When we consume glucose, it is transported to our vascular system from the small intestines, which raises our blood glucose levels. The pancreas then secretes insulin which shuttles the glucose to each cell where it’s needed. When we consume fructose, it is solely metabolized in the liver, producing high triglyceride levels, which have been found to be an independent risk factor for cardiovascular disease.(5) In addition, fructose is a very low glycemic carbohydrate and does not induce insulin secretion, nor does it boost leptin production, both of which are key signals for decreasing hunger.(6) If one doesn’t feel satiated after one eats, what will one do? Keep eating. Hence the name, “fat carb”. Eat it, get fat; eat more, get fatter.
Russ Bianchi, a pharmacologist, and toxicologist explains: “there is no safe form of fructose available from any source, unless already existing in an unprocessed apple or other piece of fruit. The science is known and epidemiologically proven.” (7)
At the end of the day, if you’re at the very least trying to get lean, fructose is your kryptonite. More importantly, if you’re at interested in your health, fructose will ensure you never reach that goal.
1. Furci, S. M. (2012). The Evolution of the Unhealthy American (P. 15). Retrieved from http://www.mindbodyconditioningsystems.com/evolution-of-the-unhealthy-american
2. (2009). Consuming fructose-sweetened, not glucose-sweetened, beverages increases visceral adiposity and lipids and decreases insulin sensitivity in overweight/obese humans. The Journal of Clinical Investigation,119(5),1322–1334. Retrieved from http://www.jci.org/articles/view/37385
3. (2012). Consumption of fructose-sweetened beverages for 10 weeks reduces net fat oxidation and energy expenditure in overweight/obese men and women. European Journal of Clinical Nutrition, 66(2), 201-8. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/21952692
4. (2008). Dietary Sugars Stimulate Fatty Acid Synthesis in Adults. Journal of Nutrition, 139(6), 1038-1046. Retrieved from http://jn.nutrition.org/content/138/6/1039.full
5. (2000). Evidence that triglycerides are an independent coronary heart disease risk factor. American Journal of Cardiology, 87(9), 1137-8. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/11053704
6. (2004). Consumption of high-fructose corn syrup in beverages may play a role in the epidemic of obesity. American Journal of Clinical Nutrition, 79(4), 537-543. Retrieved from http://ajcn.nutrition.org/content/79/4/537.full
7. (2005, September 14). Is lot’s of fructose water foolhardy? Apology, too. [Web log message]. Retrieved from http://blogcritics.org/is-lots-of-fructose-water-foolhardy/