Marijuana is a complex plant, containing over 500 different compounds. The most well-known chemicals are CBD, or cannabidiol, and delta-9-tetrahydrocannabinol, or THC. THC is the active ingredient responsible for the high that cannabis users experience. THC is also the compound that gives us the munchies.
When an individual ingests cannabis, THC flows into all centers of the brain. One of these centers is called the endocannabinoid center, which is responsible for food intake regulation. According to an article in Vice, neurons in this center, called POMCs, are highly stimulated. Neurologists believe that POMC's function is to make us feel satiated after eating. Yet when stimulated by THC, tests have shown that the normal functioning of POMC's actually flips, which create the opposite effect, making us want to eat more rather than less.
But neurology is complex, and tests have shown there are other factors that contribute to the munchie effect. An article in the Smithsonian explains that THC fits into the receptors in the brain's olfactory bulb, which increases our sensitivity to the smell and taste of food. Researchers tested the response of mice to the scent of banana and almond oils. The mice sniffed and soon enough stopped, due to a well-known phenomenon called "olfactory habituation." However, when mice were dosed with THC, they kept on sniffing, reflecting the enhanced sensitivity of smell. These same mice also ate more food than their sober counterparts.
According to Live Science, THC's effects are well known in hospitals for helping cancer patients who have lost their appetites. When patients have advanced cancer, they often experience a wasting syndrome, where they burn through calories rapidly. With the added factor of loss of appetite, their health can spiral downwards, fast. Yet tests have shown that patients who take THC experience an increased appetite, an increased appreciation for food, and a reduction in nausea that is caused by chemotherapy. Basically, THC can vastly improve the quality of their life.
THC is also known for releasing dopamine into the brain; the chemicals that make us feel happy and euphoric. With increased dopamine, our muscles relax and we can be relieved of chronic pain and ailments, as well as get a good night's sleep. To wrap up, THC affects the centers that are responsible for our senses. It increases our sense of smell as well as our appetite and can enrich our overall quality of life. It makes us feel less inhibited to reach for things we might not normally eat, so can also affect our waistline!