The Science of "Getting the Munchies" & Why it Helps the Critically Ill.

by HelloMD

Cannabis has always been associated with appetite stimulation - that sensation you feel soon after consuming marijuana - some folks call it "the munchies". Well, now science is beginning to back up that association. Research has shown that cannabis does have a positive effect on appetite. For people whose appetite has been affected by chronic illness, this is encouraging news. Cannabis may help restore their appetite, allowing them to eat and back on the path to good health.

Critical Illness and Appetite

People who are sick often do not eat or take in sufficient quantities of food, and malnourishment is common among the critically ill. A study of patients in a hospital found that 40 percent of critically ill patients were malnourished upon admission and that their status often deteriorated across the hospital stay. Furthermore, malnourishment often lingers for a period of time after discharge, which delays the healing process.

While symptoms of a patient's chronic illness, including nausea, vomiting, and chronic pain, may contribute to the inability or lack of desire to eat, there are actual biological changes that impair appetite. For example, critically ill patients have significantly lower levels of ghrelin, a hormone produced by the gastrointestinal tract. This hormone is associated with appetite stimulation and is at its highest levels after fasting and prior to eating. In critically ill patients, ghrelin [is significantly lower](http://www.ccforum.com/content/10/1/R10# B2) than in healthy individuals. Levels of the peptide hormone leptin are similarly affected. This hormone is associated with energy balance, increasing appetite when the body's energy is low.

Studies of those who suffer from anorexia nervosa, a mental illness in which patients have a distorted body image and avoid food, may provide insight into the effects of illness-induced anorexia. These studies have found that among anorexia patients:

The Endocannabinoid System and Appetite

In addition to ghrelin and leptin, the endocannabinoid system in the body can affect appetite. This complex system includes cannabinoid receptors in the central and peripheral nervous system, as well as in the immune system, and is associated with balance or homeostasis. Some of these receptors, particularly CB1 receptors, are concentrated in portions of the brain that affect memory, movement, emotions, higher cognition, and appetite. Naturally occurring cannabinoids produced by the human body bind with these receptors to create balance. Disrupting this binding can either reduce or increase the effects on memory, emotions, and appetite. Disruptions can be caused by medication, illness, and cannabinoids from cannabis.

THC and Appetite

Delta-tetrahydrocannabinol (THC), is the most common cannabinoid in cannabis and is responsible for the high associated with the plant. THC is also responsible for stimulating appetite.

THC binds with CB1 receptors, including those associated with taste and pleasure, food intake, and energy balance. When THC is taken in, it is rapidly taken up by the CB1 receptors and appetite is enhanced, eating is more pleasurable, and the feeling of satiety (fullness) is reduced.

In addition to enhancing CB1 receptors in the brain, THC also:

  • Improves sense of smell. A recent study of mice found that THC enhanced their ability to smell food, thus increasing the amount of food they eat.\
  • Improves taste. THC increases the ability to taste food, making it more pleasurable to eat and increasing the rewards associated with eating.\
  • Increases levels of ghrelin and leptin,\

Taking Cannabis

Medical cannabis comes in a variety of forms and can be taken a variety of ways. Smoking, which introduces the cannabinoids to the system quickly, may be difficult for people who are feeling nauseous. For those suffering from vomiting, an edible form of cannabis may not be effective. Luckily there are a number of alternatives, including:

  • Cannabis oil - a concentrated form of cannabinoids that can be placed under the tongue (sublingual) or added to food, drink or tablets.
  • Vaporization - this process involves heating the cannabis to a point below combustion (burning) and inhaling the vapor created. Benefits include fast delivery of cannabinoids and reduced effects on the lung.

Another option is Marinol®. This synthetic form of THC has been approved by the FDA for use in patients with acquired immune deficiency syndrome (AIDS) and anorexia to stimulate appetite. It has also been approved for treating the side effects of chemotherapy in cancer patients who suffer from vomiting and nausea and who do not respond to traditional medications. However, compared to cannabis-based THC, marinol can increase nausea and vomiting in some patients and is more expensive. Plus naturally occurring THC is often balanced with cannabidiol (CBD), a cannabinoid that can counteract the "high" of THC without decreasing the appetite-stimulating property.

Improved Quality of Life

Good nutrition is always important. But the effects of poor nutrition can be measured in the critically ill. Malnourishment is associated with increased complications, longer hospital stays, and poorer recovery for critically ill patients.

In addition, patients who have a critical illness often suffer from depression and anxiety. These conditions are worsened by malnourishment and by the inability to eat or enjoy food. By stimulating the appetite, cannabis can help patients feel better and recover sooner. Cannabis is also associated with improving depression and anxiety. Patients who feel better, have an improved quality of life and can cope better with their critical illness.

Patients should talk with their medical marijuana provider to see if they could benefit from the appetite-stimulating properties of cannabis and to identify the best delivery option for their condition and symptoms.