High fructose corn syrup leads to obesity

Sugar is sugar and calories are calories . . . or so we’ve always believed. Research from Princeton Neuroscience Institute, however, suggests otherwise.

According to a paper recently published in Pharmacology, Biochemistry, and Behavior1, rats that consumed high fructose corn syrup (HFCS) gained much more weight than rats that consumed equal amounts of sucrose (table sugar). The study was two-part: In the first half of the study, the researchers gave rats water sweetened with either HFCS or sucrose. Caloric intake between the groups was equal, and the sugar solution actually contributed a greater number of calories to that experimental group’s diet than HFCS contributed to the other group’s diet. Nevertheless, the rats that consumed the HFCS solution gained significantly more weight than the rats who drank the sugar solution.

In the second half of the study, the researchers looked at long-term effects of HFCS consumption by feeding one group of rats a diet high in HFCS and comparing them to another group that ate “normal” rat chow. After 6 months, the rats eating more HFCS developed metabolic syndrome: an increase in circulating triglycerides (which increase risk of heart disease2), abnormal weight gain, and increased fat deposits, particularly around the abdomen. Sound like signs of obesity? No one has yet determined why HFCS affects rats (and probably humans) so much more aversely than sucrose. Structural differences between the two compounds, however, do suggest a few possibilities.

Sucrose HFCS
50% fructose, 50% glucose55% fructose, 42% glucose (3% higher saccharides) Fructose molecules are bound to glucose 1-1Fructose molecules are free and unbound (due to processing)

The lack of fructose-glucose bond in HFCS makes those fructose molecules easier and faster to metabolize than the fructose molecules in sucrose. Scientist hypothesize that extra fructose is metabolized directly into fat, which takes less energy to store (and therefore leaves more calories to create that “beer belly”), whereas excess glucose is more commonly stored as a carbohydrate or glycogen. Scientists may not yet have the “why” nailed down, but the research thus far may provide ample motivation to choose water over a soda next time you sit down to dinner.

1 Bocarsly, M., Powell, E., Avena, N., & Hoebel, B. (2010). High-fructose corn syrup causes characteristics of obesity in rats: Increased body weight, body fat and triglyceride levels Pharmacology Biochemistry and Behavior DOI: 10.1016/j.pbb.2010.02.012

2 Gotto AM Jr (1998). Triglyceride: the forgotten risk factor. Circulation, 97 (11), 1027-8 PMID: 9531247

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