Fructose apparently tricks the brain into thinking you are hungrier than you actually are. Unlike carbohydrates made up of glucose, fructose does not stimulate the pancreas into producing insulin. Nor does it promote the production of leptin, a hormone made by fat cells. Under normal conditions, the amount of insulin and leptin in the body signal to the brain that you’ve had enough to eat. Meanwhile, fructose doesn’t seem to suppress the production of ghrelin, the hormone that triggers appetite, which normally declines after eating.
In tinkering with the body’s hormonal balance, fructose also causes the liver to spew more fat into the bloodstream than normal. Thus, consuming foods or drinks laced with HFCS is like eating a high-fat meal. In doing so, we not only gobble down more calories with every mouthful, but we also store more of those calories as fat. That can mean only one thing: a bigger waistline.