Gastric Bypass Tied to Reduced Fat Intake in Humans, Rats

Humans consume less dietary fat six years post-op; rats eat more low-fat chow after surgery

THURSDAY, Aug. 4 (HealthDay News) -- Gastric bypass is associated with reduced intake of and preference for fat in rats, and reduced intake of dietary fat for humans, according to an experimental study published online in July 6 in the American Journal of Physiology.

Carel W. Le Roux, M.D., Ph.D., from the Imperial College London, and colleagues investigated how gastric bypass affects the intake and preference for high-fat food in an experimental study of rats and a clinical trial of humans.

The investigators found that, compared to patients who underwent vertical-banded gastroplasty, the patients who underwent gastric bypass consumed a significantly lower proportion of dietary fat six years after surgery. Compared to the sham-operated control rats, rats that had undergone gastric bypass significantly reduced their total fat and calorie intake, increased their standard low-fat chow consumption, and exhibited a significantly lower preference for Intralipid concentrations above 0.5 percent in an ascending concentration series of two-bottle preference tests after 10 to 200 days of surgery. In a brief access test using similar Intralipid concentrations, there was no difference in the appetites or consumption between the two groups of rats. An increase in levels of glucagon-like peptide was seen after gastric bypass surgery. A conditioned taste aversion occurred in rats who were administered an oral gavage of 1 ml corn oil after saccharin.

"Patients randomized to receive gastric bypass report a lower dietary fat intake compared to patients after vertical-banded gastroplasty six years after surgery," the authors write. "The results of our rat experiments showed a shift away from solid high-fat to solid low-fat food after gastric bypass."

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