Weight Loss is More Difficult for Obese Individuals: Appetite Changes in the Brain

Weight loss is difficult for many, many individuals. Our country has a serious problem with obesity. According to Jamie Oliver (who recently gave a presentation on the subject at the TED conference), currently 10% of the United States health care costs are spent on obesity. Hundreds of millions of dollars are being spent on what, ultimately, is preventable disease. It is therefore no wonder that chemists are desperately trying to discover what controls weight loss in the body, and are trying to produce methods that will make weight loss more effective.

Eating less food - intaking fewer calories - is the obvious answer. For many people, it's been a question of "will power": if you really, really want to lose the weight, and you're a strong person, you'll be able to deny yourself that extra serving of food. However, a research group at Oregon University have recently published a study in the journal Cell Metabolism that makes the issue much more complicated. The research group outlined their results which showed that being obese makes chemical changes to the brain, radically altering the ability of the body to regulate appetite. This leads to an unfortunate cycle: you gain weight, it becomes harder to deny yourself food, you gain more weight, and so forth.

Weight loss through appetite control is normally controlled by the bodies release of a hormone called leptin. Normally, if you start to build up too many fat cells, leptin gets released into the bloodstream and it in turn stimulates the release of peptides (short snippets of amino acids - tiny proteins, in other words) which have powerful appetite suppressing properties. The body senses that it's getting too fat and takes action to prevent the situation from getting worse. However, the Oregon researchers found that in obese individuals, there is a higher level of another chemical called "cytokine signalling 3". This molecule interferes with the release of leptin, which in turn means that the bodies natural appetite suppressants (the short peptitdes) never get released.

It's not clear precisely what came first, or which is cause and which is effect. All that the scientists know at this point is that obese individuals have too much of the cytokine molecule, and that's interfering (through the above described process) with the bodies natural method of regulating how much fat it stores. It's not clear if becoming obese increases the level of the cytokine, or if some people just naturally have too much of the cytokine, if certain foods have higher effects than others in boosting the cytokine levels - much is still unclear. However, scientists now have a target. If they can design a molecule, a medicine, which inhibits or "shuts down" the reactivity of the cytokine, then the leptin will be free to do its normal job and the body's systems will go back to normal.

Weight loss is a terrible struggle. The next time a fat person walks by, don't pity them, or scorn them. Realize that they have a disease, and maybe it was caused by greed or gluttony, but it might just turn out that they were born with higher levels of the cytokine - and literally couldn't help themselves, strong-willed or not.

Source:

"Diet-Induced Obesity Causes Severe but Reversible Leptin Resistance in Arcuate Melanocortin Neurons".

Pablo J. Enriori, Anne E. Evans, Puspha Sinnayah, Erin E. Jobst, Luciana Tonelli-Lemos, Sonja K. Billes, Maria M. Glavas, Bernadette E. Grayson, Mario Perello, Eduardo A. Nillni, Kevin L. Grove and Michael A. Cowley

Cell Metabolism, a journal of Elsevier, Inc.