So you are frustrated after the long workouts and still there is little or no weight loss, the case is not the same with others, some people don't do workouts eat twice as much as you, still they dont gain weight here is how. It's called leptin, and it tells your brain to suppress hunger. Here's how to make the most of it. During a recent physical, my doctor suggested I lose about eight pounds. No problem, I figured: I'd simply step up my workouts and skip my nightly dessert. But after several weeks, I'd lost almost no weight and was always hungry.

Sound familiar? If so, you'll be interested in leptin, a chemical that could be the "master hormone" for your appetite. Produced in the body's fat cells, leptin travels to the brain after a meal to suppress hunger. As the meal is digested, leptin levels fall, and appetite rebuilds.

But this exquisite system can be easily disrupted. A major culprit? Elevated triglycerides in the blood, which prevent leptin from reaching the brain, allowing hunger feelings to persist. Fortunately, you can take steps to bathe your brain in leptin and quell appetite naturally:

Eat foods low in triglycerides: Be wary of foods high in dairy fat (like whole milk and ice cream), which is 98 percent triglycerides.

Get hooked on fish oil: It may lower triglycerides and also facilitate leptin's passage to the brain.

Sleep about eight hours: Anything less is associated with lower levels of leptin in the blood and brain.

Exercise often: Regular activity lowers triglycerides and helps the brain absorb more leptin.

An additional bonus to maintaining robust levels of leptin in the brain: a flatter belly. When appetite (and, thus, food intake) is suppressed by leptin, the body first turns to its most readily available source of body fat, which is stored around the belly, for fuel.

Thomas Crook, Ph.D., a clinical psychologist, has conducted extensive research to improve our understanding of how the brain works. He is a former research program director at the National Institute of Mental Health and is CEO of Cognitive Research Corp. in St. Petersburg, Fla.