Fructose - the sugar that makes you fat
Several different studies have cast fructose as the arch-villain in the expansion of your waistline.
People in the study who drank a fructose-based breakfast drink produced twice as much body fat as those who had a glucose-only breakfast drink. This was measured during the four hours after breakfast.
Fructose is mainly a fruit sugar, also found to a lesser extent in vegetables. Sweet fruits and fruit juice are high in fructose. But by far the worst culprits are processed foods, because most of them contain fructose in the form of high-fructose corn syrup (HFCS) (2) or sucrose (which is broken down into fructose and glucose). Virtually every processed food is sweetened - biscuits, breads, cereals, crackers, juices, soups, salad dressings, supermarket sauces and other beverages all have it. HFCS is a cheap way for food manufacturers to sweeten their products and make them more addictive.
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A small glass of fruit or vegetable juice that you squeeze yourself is a great source of living nutrition - enjoy up to one glass per day. But remember that orange, carrot and beet juice is high in fructose, and not helpful if you are trying to lose weight.
The research shows that fructose dramatically enhances lipogenesis - the process in which your body converts sugar into fat. Your liver converts fructose into blood fats (triglycerides). Blood triglyceride is part of a standard cholesterol test, and a high level is a risk factor for heart disease, among many other ailments. (3)
1. Dietary sugars stimulate fatty acid synthesis in adults. Parks, E. J. et al., Journal of Nutrition
2. Nature Clinical Practice Endocrinology & Metabolism (Vol. 2, pp. 447-458), August 2006.
3. Loren Cordain, S Boyd Eaton, Anthony Sebastian, Neil Mann, Staffan Lindeberg, Bruce A Watkins, James H O'Keefe, Janette Brand-Miller. Origins and evolution of the Western diet: health implications for the 21st century. Am J Clin Nutr 2005;81:341-54.