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Male rats given high-fructose corn syrup gained 157% in 6 months vs 102% with rat chow only
Monday, March 28, 2011 4:15 pm Email this article
Growing male rats given 24-hour access to water containing 8% high-fructose corn syrup (HFCS) in addition to water and given access to regular rat chow, gained 157% of their body weight in six months compared to a normal weight gain of 102% for rats given access to rat chow and water only according to a study from researchers at Princeton University in Princeton, New Jersey, USA. Elevated Triglycerides
Elevated Triglycerides from HFCS May Have Added To Body Fat
The rats given the HFCS had elevated triglycerides levels in their blood—201 mg per deciliter for rats given access to 24-hour HFCS versus 147 mg per deciliter for rats given rat chow only.
The researchers speculated that this may have been part of the reason that the rats given HFCS gained more weight and more body fat.
“One important factor might be that the HFCS-induced weight gain is accompanied with hyper-triglyceridemia,” the researchers wrote.
“Given the known role of [triglycerides] in fat accrual (Owen et al., 1979), the elevated [triglyceride] levels observed in the rats fed HFCS in the present study might account, in part, for the deposition of body fat.”
No Difference in Insulin
No difference in insulin levels in rats given HFCS
“There were no differences found among the groups in serum insulin levels,” the researchers noted.
Conclusion: Rats Gained More Weight on HFCS than on Sucrose
“In the current study, long-term access to HFCS in rats led to obesity, while sucrose [table sugar] did not,” the researchers noted.
“In Experiment 2 (long-term study, 6-7 months), HFCS caused an increase in body weight greater than that of sucrose [table sugar] in both male and female rats.”
Conclusion: The Previously Found Rats Maintained Normal Bodyweight consuming 10% Sucrose
“We have previously shown that rats are able to adjust for the excess calories obtained when consuming 10% sucrose by taking in fewer calories of chow and thereby maintaining a normal bodyweight (Avena et al., 2008).”
Conclusion: HFCS Appears to Act Differently Than Sucrose on Body Weight
“Several studies compare the effects of acute sucrose and HFCS on weight gain and metabolic profiles in humans (Akhavan and Anderson, 2007; Melanson et al., 2008; Stanhope et al., 2008), and most conclude that sucrose [table sugar] and HFCS similarly affect the body in the short term (Stanhope et al., 2008),” the authors noted.
“However, little is known of the long-term effects of HFCS consumption on fat accrual.”
“The preclinical data in Experiment 2 suggest that long-term exposure to HFCS compared with sucrose differentially affects body fat accrual,” the researchers continued.
Conclusion: Rats With Access To HFCS Do NOT Maintain A Normal Body Weight
“In summary, rats maintained on a diet rich in HFCS for 6 or 7 months show abnormal weight gain, increased circulating [triglycerides] and augmented fat deposition,” they noted.
“All of these factors indicate obesity.”
“Thus, over-consumption of HFCS could very well be a major factor in the ‘obesity epidemic’, which correlates with the upsurge in the use of HFCS,” the authors concluded.
Why Does HFCS Cause Excess Weight Gain?
No Difference In Total Calorie Intake in 2-Month Study Giving Access to HFCS 12-hours per day
In a shorter 8-week study, there was was no difference in total calories consumed in rats given access to an 8% HFCS solution versus those given access to a 10% sucrose solution, however, the the HFCS group gained more weight even though the rats consumed fewer calories from the HFCS than the rats did from the sucrose.
Total Calorie Intake
Total Calorie Intake NOT measured in 6- and 7-Month Studies Giving Access to HFCS 24-hours per day
However, it appears that they did NOT measure total calorie intake in two longer studies—6 months in male rats and 7 months in female rats, given access to HFCS 24-hours per day or HFCS 12-hours per day versus control rats given rat chow only.
Possible Metabolic Changes Leading to Increased Fat Intake and Calorie Intake in Long-Term
Possible metabolic changes—leptin resistance and insulin resistance—leading to increased fat intake and calorie intake in long-term
Therefore, it is possible that metabolic changes occurred in the longer-term leading to an increase in calorie intake.
However, they also noted that previous studies have found that rats given sucrose did NOT gain an excess amount of weight.
The paper notes…
Elevated Triglycerides Increases Fat Intake
Elevated triglycerides increase fat intake in the long-term
“Previous research has suggested that an elevated level of circulating [triglycerides] is, in part, responsible for an increase in high-fat intake (Chang et al., 2007).”
“Therefore by chronically elevating serum [triglyceride] levels, HFCS may create a propensity towards fat intake and fat deposition.”
Could cause leptin resistance and insulin resistance in the long-term
“This could work to induce leptin and insulin resistance.”
May Cause Over-Consumption
Elevated triglycerides increase fat intake in the long-term
“Taken together, leptin or insulin resistance and elevated [triglyceride] serum levels may promulgate food over-consumption and contribute to the corresponding obesity.”
Males Gained More Than Females
Males Gained More Weight and at a Faster Pace Than Females
They also noted that male rats given access to HFCS 24-Hours per day gained more weight and at a faster pace than female rats.
Bocarsly M, Powell E, Avena N, Hoebel B. High-fructose corn syrup causes characteristics of obesity in rats: Increased body weight, body fat and triglyceride levels. Pharmacol Biochem Behav. 2010 Nov, 97(1):101-06.
AUTHOR’S CONTACT INFORMATION
Bartley G. Hoebel
Department of Psychology
Princeton, NJ 08540, USA
Tel.: +1 609 258 4463
fax: +1 609 258 1113
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