French researchers attempt to resolve questions about low-carb diets

• A study of protein-munching rats shows that a low-carb diet sparks a chain of biological events that ultimately curbs hunger.
• The French researchers explain it this way: Protein, the staple of such weight-loss regimens, appears to increase glucose production in the small intestine -- the rise of which is monitored by the liver and then registered by the brain.
• In turn, the brain sends out an "all full" message, cutting back on the drive to eat more.
• "The current findings provide an answer to the question of how protein-enriched meals decrease hunger and reduce eating, unsolved up to now," the study authors, led by Gilles Mithieux of the Institut National de la Sante et de la Recherche Medicale in Lyon, France, said in a prepared statement.
• "This novel understanding of the effect of diet protein will open new gates in the elaboration of future medical treatments of obesity," Mithieux said.
• Reporting in the November issue of Cell Metabolism, the French team found that by the end of just one week, rats on the protein-rich regimen had consumed 15 percent less food than those in the starch-diet group.
• The protein-diet rats also gained significantly less weight over the course of the week than the starch-diet rats, the study found.
• Even after food absorption had been completed, the small intestines of the protein-diet rats continued to deliver high levels of glucose into their portal vein -- a vessel that shuttles blood from the digestive system and other organs to the liver.
• Glucose sensors in the liver of these protein-diet rats were found, in turn, to have signaled those areas of the brain responsible for appetite control -- bearing the message that liver glucose levels had risen.