According to their research published today in the New England Journal of Medicine, obese people have on average, a level of PYY3-36 that is one third lower than that of lean volunteers.
The researchers also found that by infusing PYY3-36, they were able to reduce the perceived appetite and calorific consumption of both the lean and overweight volunteers by around a third for a period of 24 hours.
Professor Steve Bloom from Imperial College London and the Hammersmith Hospital, and one of the paper's authors, comments: "The discovery that obese people have lower levels of PYY3-36, an important factor limiting appetite, suggests a possible new treatment for the millions suffering from obesity."
"Our previous research has shown that it is possible to reduce calorific consumption in lean volunteers by giving PYY3-36. These new findings suggest boosting PYY3-36 offers a novel approach towards treating the epidemic of obesity in our society."
Dr. Rachel Batterham, an author of the paper who carried out the research as a Wellcome Trust researcher while at Imperial College London, and who is now based at University College London, adds: "PYY3-36 is a naturally occurring hormone that is released from the gut in response to eating, and it signals to the brain that a meal has been eaten. This deficiency of PYY3-36 we observed in obese subjects could be the reason why some people become obese and others don't. Further research is now needed to establish whether we can change people's diet to increase the release of this hormone."
The researchers studied twelve obese and twelve lean volunteers in a double blind, placebo controlled crossover study. After an overnight fast subjects attended the Hammersmith Hospital Sir John McMichael Research Centre at 8.30 am. They were then given a ninety minute infusion (placed on an intravenous drip) of either PYY3-36 or placebo (a saline solution). Two hours after the end of the infusion, where the volunteers did not know if they were receiving the PYY3-36 or the placebo, they were offered an unlimited buffet meal.
All 24 volunteers ate less on the day when they received a PYY3-36 infusion compared with the placebo day. Overall PYY3-36 reduced calorific intake by a third in both the lean and obese subjects.
The research was supported in part by the Wellcome Trust and by a grant from the Medical Research Council.
Notes to editors:
1. Inhibition of Food Intake in Obese Subjects by Peptide YY3-36, New England Journal of Medicine, 4 September 2003.
2. Consistently rated in the top three UK university institutions, Imperial College London is a world leading science-based university whose reputation for excellence in teaching and research attracts students (10,000) and staff (5,000) of the highest international quality. Innovative research at the College explores the interface between science, medicine, engineering and management and delivers practical solutions that enhance the quality of life and the environment - underpinned by a dynamic enterprise culture. Website: http://www.