Just after you finish gorging on burger, french fries and cola, a protein produced by the liver sends a signal that fat is on the way, according to a study.
In the study on mice, researchers have found that the liver produces a protein called adropin, which rises in response to high-fat foods and falls after fasting.
Apparently the protein plays a role in governing the activity of other metabolic genes, especially those involved in the production of lipids from carbohydrates.
Previously the presence of the protein in obese animals was found to play a role in insulin response and in preventing the buildup of fat in the liver (a condition known as nonalcoholic fatty liver disease), said the researchers.
"What is remarkable is that it appears that this factor is specifically regulated by the fat content of the diet," making it one of the first such factors ever discovered, said Andrew Butler of Pennington Biomedical Research Center, part of the Louisiana State University System.
In the wake of the latest findings, scientists believe that treatments designed to deliver adropin or otherwise boost its levels may hold promise in the war against obesity and associated metabolic disorders, including fatty liver disease and type 2 diabetes.
Already the researchers have found that animals that become obese after eating a high-fat diet for a period of 3 months or due to a genetic mutation don't produce adropin normally.
However, Butler said that obese animals that are manipulated to produce excess adropin or that are given the protein show less fat in their livers and become more responsive to insulin. The mice also ultimately eat less and lose weight, but the other metabolic improvements do not depend on the animals' shrinking waistlines.
"The good news is that when you provide a synthetic version of the peptide, it reverses some of the consequences of obesity," he said.
Now the researchers want to know whether mice that lack adropin become obese and show evidence of the metabolic syndrome, a cluster of diseases associated with obesity and insulin resistance.
Also, the protein is even produced in the brain, indicating it may also affect behaviour and metabolism in as-yet-undiscovered ways.
However, researchers are still not sure how adropin works its magic. They said that its benefits could involve effects within the liver and/or hormonal actions on other body tissues.
"In summary, adropin is a newly discovered secreted peptide that is involved in energy homeostasis and lipid metabolism ... Adropin may form the basis for the development of new therapeutic targets for treating metabolic disorders associated with obesity," wrote the researchers.
The study is published in the latest issue of the journal Cell Metabolism, a Cell Press publication.