Researchers in the Eating Disorders Research Group at the Garvan Institute in Sydney have shown for the first time that dynorphins, the body’s natural version of morphine, play a significant role in regulating weight gain and weight loss.

Lead researcher, Dr Amanda Sainsbury-Salis says: “The dynorphins are natural brain chemicals found in what I call ‘the neurochemical soup’ around the hypothalamus - the part of the brain that regulates our appetite and body weight. To test whether dynorphins play a significant role in weight loss, we generated mice that were unable to produce any dynorphins. We found that these mice had significantly less body fat than the normal group, and they lost 15-20% more weight than normal mice while eating the same amounts of food.”

The Garvan study suggests that, for people genetically predisposed to produce higher levels of dynorphins, the body will store more fat and lose less fat than for people with lower levels, even when they are placed on the same calorie-restricted diet. This may help explain why some people find it harder to lose weight than others, despite their best efforts at dieting.

This latest research at Garvan offers a promising new direction in the development of a new type of weight loss drugs that do not rely on appetite suppression to produce weight loss. This new class of weight loss drugs could become available in about 10 years.

This research was published in the July 2007 issue of Molecular Endocrinology.