Glucose and fructose are monosaccharides with the same number of carbons, hydrogens, and oxygens. But is there a difference in how our bodies utilize them?
In a study of overweight and obese adults, it was found that fructose (but not glucose) contributes to insulin-resistance, visceral adiposity (fat around the organs), and the production of very low density lipoproteins (vLDLs) - the so-called “bad” cholesterol carriers (1). Glucose can be metabolized by virtually every cell in the human body, and is directly involved in the production of ATP (energy). Fructose, however, is only metabolized by the liver, and is turned into fat, in the form of free fatty acids, triglycerides and vLDLs.
In another study, the effect of fructose versus glucose on appetite was examined. Compared with glucose, fructose ingestion was linked to a smaller increase in systemic insulin and GLP-1, two hormones involved in satiety (2). Furthermore, fructose does not reduce levels of the hunger hormone, ghrelin. So not only does high fructose intake make you fat and contribute to chronic disease, it also keeps you from feeling full, presumably making you eat more.
Be especially wary of high-fructose corn syrup, which is an unnatural combination of fructose and glucose, with fructose content in the 55-75% range. If you are trying to lose weight, also limit your intake of high-fructose fruits, such as apples, dates, grapes, and mangoes.