In 1994 at New York’s Rockefeller University, Dr. Jeffrey Friedman and his research team discovered that the fat cells of genetically obese mice failed to produce a chemical called Leptin. Leptin was the first adipokine and the first hormone shown to be made, exclusively by fat cells. Leptin’s primary function throughout human history has been to sense body fat for survival during famine. Many scientists believe that the main evolutionary role of leptin was not to regulate weight or appetite, but to regulate fertility. Leptin is absolutely necessary for the normal function of reproductive organs. As fat stores fall, leptin levels drop. At a certain level of thinness, a woman’s ovaries stop functioning, solely because of leptin deficiency. This effect is seen today in slim young women with very low body fat. Leptin lets the brain know when there is enough food available to support offspring and prevents reproduction when food is scarce.

Leptin will control fat loss

Leptin is a naturally occurring chemical substance that many organisms produce in response to increasing fat content in the body. In essence, it is the substance that tells the brain the body is well nourished and can stop eating, thus functioning as a natural regulator of body weight. In the 1990s, however, scientists noticed that obese individuals are frequently leptin resistant---their bodies do not respond to the natural regulating effect of leptin. Correcting this resistance is thought to be one key to successful, long-term weight loss.

If you are leptin resistant, your own body is essentially sabotaging your efforts at weight control. In the first place, your brain is not receiving signals to cease eating when fat stores accumulate, and you'll find yourself hungry despite knowing rationally that you should be full. To balance your body's chemistry, you'll need to regulate yourself mentally since your body can't do it for you. This will take consistent determination and will power.

Exercise even when your body tells you to quit. When the body becomes leptin resistant, it becomes accustomed to high levels of the chemical in the blood. A little weight loss can trigger a decrease in leptin, making your appetite larger and affecting your metabolism negatively. Even though the body has plenty of fat stores to burn, the muscles cease to do so in response to decreasing leptin. You may not see results quickly because of this, and you may find yourself particularly exhausted by exercise. Do it anyway, because you can't correct leptin resistance without reaching a healthy weight.

Simply stated, leptin is a very powerful and influential hormone discovered approximately 10 years ago produced by fat cells, that has totally changed the way that science looks at fat, nutrition, and metabolism in general.

Prior to leptin's discovery, fat was viewed as strictly an energy storage depot, an ugly one at that and one most everyone was trying to get rid of. After it was discovered that fat produced the hormone leptin (and subsequently it was discovered that fat produced other very significant hormones), fat became an endocrine organ like the ovaries, pancreas and pituitary influencing the rest of the body and, in particular, the brain. It tells the brain what to do about life's two main biological goals: eating and reproduction.

I would say now that rather than your brain being in control of the rest of the body, it is, in fact, subservient to your fat. Your fat, by way of leptin, tells your brain whether you should be hungry, eat and make more fat, whether you should reproduce and make babies, or whether to "hunker down" and work overtime to maintain and repair yourself.

It plays a large role in inflammation, immunity, cardiovascular disease, diabetes, osteoporosis and all other diseases of aging, and perhaps, aging itself.

Both insulin and leptin work together to control the quality of one's metabolism and, to a significant extent, the rate of metabolism via nervous system control.

Each and every one of us is a combination of lives within lives. We are made up of trillions of individual living cells that each must maintain itself. Even more significantly, the cells must communicate and interact with each other to form a republic of cells that we call our individual self. It is the communication among the individual cells that will determine our health and our life. The communication takes place by hormones. Insulin and leptin are the major hormones regulating metabolism.

Metabolism can roughly be defined as the chemistry that turns food into life, and therefore insulin and leptin are critical to health and disease. Insulin works mostly at the individual cell level, telling the vast majority of cells whether to burn or store fat or sugar and whether to utilize that energy for maintenance and repair or reproduction.

Leptin, on the other hand, controls the energy storage and utilization of the entire republic of cells allowing the body to communicate with the brain about how much energy (fat) the republic has stored, and whether it needs more, or should burn some off, and whether it is an advantageous time nutritionally-speaking for the republic to reproduce or not.

Controlling hunger is one way that leptin controls energy storage. Hunger is a very powerful and deep-seated drive that, if stimulated long enough, will make you eat and store more energy. The only way to eat less in the long-term is to not be hungry.

Leptin also very powerfully influences energy utilization and fat burning via its effects on the sympathetic nervous system. There is critical importance for controlling leptin in health and disease.

I want to largely emphasize the importance of reducing grains in your diet and other non-fiber forms of carbohydrate that readily turn into sugar. Also, very importantly, I want to stress differences among fats and to stress eating high quality beneficial fats, and avoiding those that are more harmful. Protein is used to replace and replenish cellular and body parts and thus, unlike carbohydrates, is an essential nutrient that must be eaten to maintain health. If protein is consumed too much, you basically end up training your body to turn protein into sugar. Sugar produces fat in the body, the good fats do not create fat in the body.