U.S.A. – A recent article in the Washington Post newspaper highlighted recent research findings on obesity and eating habits linked to hormones. The article said that scientists today are a step closer to understanding why it is so hard to lose weight.

    In papers published in the journal Science, two research teams describe newfound powers of leptin, the mysterious hormone that helps govern hunger and satiety. It appears that the substance, produced by fat cells, plays a crucial role in establishing the brain's circuitry before birth, and retains the ability to subtly rewire those neural connections throughout life.

    The observations - made in mice - but which scientists believe may also apply to human beings, offer a peek at the cellular workings of one of life's few essential impulses: the drive to eat. The papers also shed light on why many people seem to have a physical "set point" - a weight their body seeks to maintain, despite a person's efforts to change it.

    "The wiring diagram of the system that regulates feeding may be different in the obese than in the lean, and that may explain why lifestyle changes aren't generally effective for achieving substantial weight loss over the long term," said Jeffrey M. Friedman, the scientist who helped lead one of the teams.

    Friedman, of the Howard Hughes Medical Institute at Rockefeller University, in New York, discovered leptin 10 years ago. When it is released by fat cells into the bloodstream, leptin works to suppress appetite. A deficiency of the hormone leads to overeating and obesity.

    However, hopes for easily losing weight by simply taking leptin have not been borne out by human experiments. The new research helps explain why. Namely, that leptin works in a delicately calibrated system whose workings may be established at least in part even before birth. That, in turn, might affect a person's propensity to be fat in adulthood.