Ever had the munchies even after you just ate? That urge to snack may be due to an overactive chemical “feedback” system that regulates appetite, food intake, fat metabolism, and body weight. The chemical culprit is called the endocannabinoid (EC) system, and it’s the latest target in medicine’s battle of the bulge. We can’t change the endocannabinoid system, but we may be able to work around it by redirecting the cues that make us overeat.

The findings are in the February issue of Food and Fitness Advisor, a monthly newsletter from Weill Medical College of Cornell University.

“What many people have traditionally viewed as a lack of willpower could actually have a biochemical basis,” says Louis J. Aronne, MD, director of the Comprehensive Weight Control Program at New York Presbyterian Hospital-Weill Cornell Medical Center.

“It’s not just a matter of lack of willpower to stop eating, or of an obesity drug not working, but the body’s counterbalancing mechanisms that stops people from losing weight.”

 

When your endocannabinoid system is activated, it increases hunger and decreases satiety, driving the desire for tasty food, says Dr. Aronne. He calls this the “feed-forward” mechanism.

“When you eat a high-fat, high- carbohydrate food, it activates the endocannabinoid system, leading you to eat even more,” he explains. “The endocannabinoid system interacts with other hormones to make you feel hungrier, increases body fat, and drives weight gain. We now know that the endocannabinoid system is overactive in obese people. In one study, obese women were found to have higher levels of endocannabinoids than lean women.”

Endocannabinoids are akin to active chemicals, cannabinoids, in marijuana that triggers its effects, including the “munchies.” There are cannabinoid receptors all over the body—including the brain, the gastrointestinal tract, and fat cells. When cannabinoid receptors are activated in the brain (in the hypothalamus), it stimulates appetite, leading to increased food intake, says Dr. Aronne.

In the gastrointestinal system, activated cannabinoid receptors interact with insulin, the hormone that brings energy from food into cells as glucose, to inhibit its effects. An overactive EC system impairs the ability of cells, especially muscle cells, to use insulin, leading to insulin resistance, the precursor to type 2 diabetes. Activating cannabinoid receptors in fat cells triggers triglyceride production, increased fat accumulation, and weight gain.

“It also appears that overactivating the EC system leads to laying down of fat in the liver, which is a key factor in insulin resistance,” says Dr. Aronne. “There is also data to show that insulin and the hormone leptin, which are important signals to the brain telling how much nutrition has come in and how much fat is stored, also interact with the EC system.”

Aside from taking medication such as rimonabant to block endocannabinoid receptors, sibutramine (Meridia) to enhance satiety and reduce appetite, or block fat absorption with orlistat (Xenical, soon to be over the counter), you can’t really alter your body chemistry, says Dr. Aronne. Both Meridia and Xenical result in an average 6-10 pounds more weight loss than placebo.

However, you can use knowledge about the EC system to help you work around it. For example, nutritionists have a number of proven strategies that can help you defuse the urge to snack or overeat, such as waiting 5-15 minutes for a craving to pass, distracting yourself with other activities (such as taking a walk), or even drinking a glass of water. If you’re able to satisfy a craving with just a small portion of a treat, then have it.

Choose foods that help increase your sense of fullness, those high in water and rich in fiber, such as fruits and vegetables; eating a piece of fruit can also help satisfy a craving for sweets. Realize that it takes the brain 20 minutes to sense that you’re full. Slow down when you eat; it promotes satiety and increases enjoyment.

A 2003 study suggests that exercise may activate cannabinoid receptors, partly accounting for the “runners’ high” and for increased appetite after a workout. 

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