The study now being pre-published online in the International Journal of Obesity shows how the team from Imperial College London gave injections of oxyntomodulin to fifteen overweight but healthy volunteers from Hammersmith Hospital, and monitored how this affected their food intake, and levels of activity.
Professor Steve Bloom, from Imperial College London, who led the research, said: "The discovery that this hormone has a double effect, increasing energy expenditure as well as reducing food intake, could be of huge importance. When most people diet, this produces a reduction in activity, which is probably an adaptive trait to conserve energy during times of famine. However this does make it especially difficult for obese individuals trying to loose weight. In contrast oxyntomodulin decreases calorific intake, but actually increases energy expenditure, making it an ideal intervention for the obese."
The researchers used fifteen healthy overweight male and female volunteers, aged between 23 and 49 years. The volunteers completed three separate four-day study sessions, where they self administered either saline or oxyntomodulin according to a double blind randomised trial.
After the first injection, the volunteers were given a meal, and their calorific intake was monitored. They spent the next two days in their normal environment, self administering oxyntomodulin three times a day before meals. On the fourth day, the volunteers came back to the hospital to have their energy expenditure measured.
They found that after the first meal, the volunteers ate on average 128 kcal or 17.4 percent less, while activity related energy expenditure increased by an average of 143 kcal or 26.2 percent.
The researchers also found a reduction in body weight by an average of 0.5 percent.
Professor Bloom added: "This discovery could provide doctors with a whole new way to treat the current obesity epidemic. We need to get away from the focus on food and start to think about how to increase exercise. The question is how to make people enjoy taking exercise and how to encourage them to do it spontaneously.
"Oxyntomodulin could work by letting the brain know it has an adequate energy supply and that it can afford to do productive things rather than concentrate solely on food seeking or conserving energy. It signals to the brain that it can increase exercise by letting it know that the energy is available to do more things.
"If used as a therapy for obesity, oxyntomodulin provides a double whammy - reducing food intake and increasing spontaneous activity."