Liver may be the key to weight regulation: Study

By Dr. Ananya Mandal, MDApr 23 2012

A team of Australian researchers have found that the liver could hold the key to treating obesity. They found that the liver plays a major role in regulating weight by communicating with the brain. The study will be published in the Journal Diabetes.

University of Melbourne researchers and those from and Austin Health have noted that the body has an innate system in place to limit excessive weight gain caused by eating fatty foods. However, the system only works in response to saturated fat in a normal diet and would not stop obesity in people who ate fat and sugar-laden diets.

The team belonging to the university's Molecular Obesity Laboratory found that an enzyme in the liver increased when fatty foods were consumed and sent a signal to the brain to reduce appetite-stimulating genes. The overall affect was that after fat was consumed the brain told the body to reduce its food intake, thereby limiting weight gain.

The researchers compared higher levels of the enzyme, called FBPase, in mice with normal levels in another group. The animals with more FBPase had half the amount of fatty tissue and ate less food than those mice without the extra enzymes. When the researchers severed the communication links between the liver and the brain, the mice ate more food, even though they had higher levels of the enzymes. FBPase's main role is to produce glucose in the liver, but researchers found it is more important in regulating body weight.

Melbourne University researcher Dr Barbara Fam said people who eat a fatty diet would still become overweight, but the system probably limited the amount of weight gained. “We actually thought that the mouse with the over-expressed enzyme would show signs of becoming diabetic since the enzyme is important in producing more glucose from the liver. However when we studied our mice in more depth, we were very surprised to see that this enzyme triggered a number of hormones that influence the control of appetite,” said Dr Barbara Fam said.

“The results suggest that consumption of a diet high in fat, causes an increase in liver FBPase that was likely put in place as a negative feedback mechanism to limit further weight gain. Importantly, FBPase does not function to control body weight under normal physiological circumstances but acts only when the system is exposed to excess nutrients such as fat. When people eat diets loaded with fat and sugars particularly over the long term, it can have a number of different effects on the body but it appears that we actually have in place an innate system that protects us from any further weight gain that could happen while eating these type of diets,” she added. She explained the liver could in future be considered as a target for treating weight-related conditions including obesity and type 2 diabetes.

More needs to be investigated to verify this in further trials, however this study has demonstrated that liver FBPase should be viewed not only as a mediator of glucose metabolism but also as an important regulator of appetite and fat.