Leptin Resistance And Obesity

More than 33 percent of the U.S. population ages 20 and older is obese, according to data reported by the Centers for Disease Control and Prevention, or CDC. Nearly 1-in-3 children is also obese. Many complicated reasons are behind the surge in obesity rates over the past few decades--one of which, scientists suggest, is a problem with the signals in the brain that tell you when to stop eating. Leptin is a hormone identified by research as having the ability to shut off your appetite and even up the number of calories your body burns. The paradox is obese people have high leptin levels, but they are resistant to the signaling that makes leptin function properly. Many anti-obesity efforts, therefore, are geared toward finding a way to reduce leptin resistance.

Leptin's History

Leptin was discovered in 1994 almost by accident when researchers noted that mice with a mutation in the gene responsible for making leptin consistently overate and rapidly became obese. When given leptin supplements, they lost weight. The discovery was heralded as opening the door to drugs that would cut obesity rates down to size. But future research proved that the way leptin worked in people was far too complicated to lead to immediate obesity treatment. For one thing, obese people already have more leptin than healthy-weight people. They were just insensitive to it, or leptin resistant.

Leptin's Role in Body

What is known about leptin is that it is produced by fat cells and circulates through the body. It is part of a system in the body that strives to stay in a state of energy balance. Its job is to make the brain signal that you've had enough to eat, and it can also increase your calorie-burning rate. However, other mechanisms, such as ghrelin, the so-called hunger hormone, and the pleasure-seeking centers of the brain can override the work of leptin.

Leptin Resistance

The level of leptin in your body grows with the level of fat you have, but the more overweight you become, the less able leptin is to curtail your weight problem. This is called leptin resistance, which refers to a range of actions your body takes to block leptin from doing its job. In practical terms, this means leptin doesn't help you feel satisfied after a meal, and it doesn't increase fat-burning after you've eaten too much. Leptin resistance can be caused by an inability of leptin to reach the appropriate region in the brain needed to send these signals, or a problem with the way brain cells respond to leptin when it does reach the brain.

Link to Obesity

Obesity and leptin resistance have a cyclical relationship. Problems with leptin signals cause you to overeat and become obese, but obesity is recognized as a disease that independently promotes leptin resistance. A high-fat diet has been shown to cause leptin resistance, according to research reported in the "American Journal of Physiology." In addition, diets high in fructose cause leptin resistance. Fructose is a simple sugar found naturally in fruits and is part of what makes up high-fructose corn syrup. In addition, Drs. Michael Roizen and Mehmet Oz, in their book "You: On a Diet," explain that you can have a tendency to gain weight as you age because over time, your brain has fewer leptin receptors.

Tackling Leptin Resistance

The good news is that leptin is somewhat interactive. You can improve leptin's performance by losing weight and eating a healthier diet. Getting active will cause your body to break down more body fat. In the process, you make your cells more sensitive to, and less resistant, to leptin. In addition, reducing the amount of food you eat with added sugars, including beverages, will result in fewer calories consumed and a better shot at avoiding the fructose-caused form of leptin resistance.