British researchers have refined our understanding of the uncertain relationship between weight gain and the hormone leptin. By examining patients who suffer from an exceedingly rare genetic leptin deficiency, they reached larger conclusions about the brain's role in determining appetite and letting one know when he or she has eaten enough. 

The disorder in question, which affects approximately one dozen individuals worldwide, is defined by a significant shortage of leptin in the body. Individuals suffering from this disorder are notoriously indiscriminate about their food choices, consuming enormous amounts of almost anything. Researchers measured their responses to timed leptin injections, first showing them a series of photographs of varied edibles ranging from comfort foods and pastries to standard fruits and vegetables. Tracing the brain's reaction to these images via MRI scans, researchers found that, after receiving the boosts, the patients' brains reacted to the imagery in much less dramatic ways, lighting up with major activity only when they'd fasted the night before - an entirely natural development. Insatiable appetites thereby became manageable for the study's duration.

Leptin, appropriately produced by fat cells themselves, regulates not only appetite but also the methods with which the body processes ingested fats. Previous studies of the effects of leptin supplements in lab rats indicated that injections serve to effectively convert fat-storage cells into fat-burning cells. This dramatic reaction is chemically facilitated by an increase in activity within the animals’ mitochondria, or the organic rod-shaped shelves that extend toward the center of each cell, effectively serving as "energy factories" within all bodily tissue. The profound cellular transformation following these leptin injections is unprecedented, creating an entirely new form of modulated cell. Affected cells actually burn the fat already present within rather than allowing it to build up gradually. After two weeks, the rats who had been injected shed more than 25% of their total body weight. The second group of rats, who did not receive injections but were placed on a restricted diet, spent most of the study searching for additional food when not plagued by a profound lack of energy due to insufficient nutrition.

While the noted relationship between leptin quantities and fat retention is not a new discovery, further research may lead to a hormonal obesity treatment. And the most recent developments confirm that, for many individuals, excessive weight gain does not come from "greedy" eating patterns but from a virtually unquenchable biological urge. As an added bonus, independent studies also imply that leptin supplements may counter depression, a condition very often found to compliment chronic obesity. Unfortunately, not all of its effects are positive: overweight individuals who also have excessive amounts of leptin in their systems are apparently more likely to suffer from asthma and colon cancer. If researchers are able to isolate its energy-boosting, fat-burning properties, they may soon develop an effective weight loss medication. The reality of this plan is clearly years or decades away, and it would, in all likelihood, only be available to the dangerously obese, but in an industry built on empty promises, such medicines could constitute a minor revolution.