Leptin and Food

Leptin is a protein hormone produced in fat tissue that is involved in the regulation of appetite and metabolism. The amount of leptin secreted into the bloodstream indicates to the brain the level of the body's fat reserves. Leptin has an inverse relationship with appetite and metabolism, meaning as leptin goes up, appetite and metabolism go down, and vice versa.

Metabolism

Leptin levels influence whether the body burns calories taken in from food, producing energy, or stores those calories as fat. As leptin levels decrease, metabolism increases, energy levels increase and the body burns fat and loses weight, and vice versa. Therefore, overweight and obese people tend to have high leptin levels in their bloodstream. High leptin levels are also involved in insulin resistance, as well as other markers for "Syndrome X," a metabolic syndrome associated with increased risk of type 2 diabetes.

Appetite

As leptin levels rise in the body, appetite levels drop. But as you eat less and begin losing weight, leptin levels drop, increasing appetite. A person's leptin levels remain consistent with their balance of body weight, food intake and energy expenditures. That is why an obese or overweight person who tries to alter this balance in an effort to lose weight has a hard time keeping that weight off. His body's status-quo leptin levels fluctuate as a result of the weight loss, triggering weight gain.

Omega-3 Fatty Acids

Several studies, including one reported in July 2002 in "Circulation: The Journal of the American Heart Association," have found that the omega-3 fatty acids in fish oil lower leptin levels in the body. Tuna, salmon, halibut, mackerel, cod, red snapper and sardines are all high in omega-3 fatty acids. The American Heart Association advises that people eat a minimum of two servings of fish per week. Other foods besides fish that are high in omega-3 fatty acids include kale, summer squash, walnuts and flaxseed.

Boosting Leptin

Many diets recommend eating foods that raise your leptin levels to decrease your appetite, not taking into account the fact that it also lowers metabolism and promotes fat storage. Nevertheless, foods that help raise leptin levels in the body include fats, carbohydrates, fiber and foods with a high-glycemic index. These include fruits, vegetables and whole grains.

Other Health Considerations

Leptin levels also correlate directly with a marker of inflammation known as C-reactive protein. High levels of this protein have been associated with increased risk of heart attack and other coronary diseases. A study in "Nature Medicine" in April of 2006 reveals that C-reactive protein binds with leptin, thereby preventing it from signaling appetite satiation in the brain.