More than a billion people are overweight or obese, creating a pressing public health problem because excessive weight is linked to an increased risk of diabetes, heart disease, strokes and certain cancers. But scientists from Britain, the United States and Australia have discovered that a hormone in the body called PYY3-36 that tells the brain when the body is full could form the basis of new weight-loss treatments.
"The discovery that PYY3-36 suppresses appetite could be of huge benefit to those struggling with weight problems," said Professor Stephen Bloom, of Imperial College London.
"It does cause an inhibition of appetite and reduces food quite significantly," he added in an interview.
Bloom believes it may be possible to identify foods which cause the release of more PYY3-36 so appetite could be limited naturally. Another option would be injections of the hormone, similar to the way diabetics ( news - web sites) take insulin, which could provide a safe long-term treatment for obesity.
EATING LESS WITHOUT FEELING DEPRIVED PYY3-36 is released by the gut after every meal. It sends signals to the feeding circuits in the brain that convey a sense of satiety that reduces the urge to eat. When the scientists compared the effects of PYY3-36 to a placebo on 12 normal-weight volunteers the people who had been given an infusion of the hormone ate 33 percent less over the next 24 hours than the placebo group.
"This is a naturally occurring hormone that affects centers in your brain. It stops you eating because it makes you feel less hungry. It is part of your natural physiology," said Dr. Caroline Small, a member of the research team which published its findings in the science journal Nature.
The doses given to the volunteers mimicked the levels that occur naturally in the body after a meal and produced no side effects. People just felt less hungry. Roger Cone, of Oregon Health and Science University in Portland who contributed to the research, described it as another piece in the puzzle that adds to the understanding of how hunger and satiety are controlled. But he added that there is still a way to go before PYY3-36 can used to fight the worldwide obesity problem.
Obesity is based on body mass index (BMI), which is calculated by dividing weight in kilograms by height in meters squared. A BMI of more than 30 is considered obese. Before the hormone can be developed into an anti-obesity treatment, scientists must first show that it produces the same satiety feeling and reduces appetite in obese people. Researchers must also work out better ways of delivering it into the body and determine how it is broken down. The volunteers in the study received intravenous infusions of PYY3-36 but the researchers think an injection could be produced.
Small said the scientists are conducting further studies and comparing the effects of the hormone infusions on normal-weight and obese people.
"There is a huge epidemic of obesity and treatments are very much needed," she said.
"You need to reduce the amount of food people eat or increase the amount of energy they expend. This would reduce the amount of food people consume by making them satiated. It is enhancing those natural signals in the brain."