Nearly four years ago I posted articles on leptin, the mysterious hormone that helps govern hunger and satiety. 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.
It appears leptin, which is 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 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. 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. Leptin acts by changing the wiring of the brain, a phenomenon known as plasticity. The hormone alters the wiring by controlling synapses -- the inputs and outputs to neurons that, in this case, regulate feeding behavior.
While leptin may modify an adult animal's leptin circuitry, it cannot redesign it. For the two-thirds of us who are overweight, the end result remains the same, we will need to optimize our aerobic exercise and eat according to our nutritional type. If progress is not being made then one needs to seriously examine the emotional factors. Typically energy psychology techniques are the most useful here. However, even in the best of circumstances there does appear to be a minority of people who do not respond to these approaches. I have long believed that there is another variable that is not yet fully appreciated. It is becoming clear that leptin physiology may be a substantial contributing factor in this area.
Washington Post April 2, 2004; Page A08