Why Does Weed Make You Hungry?

If you’ve ever smoked weed, chances are you've felt pretty hungry afterwards. Maybe you even said, “I’m starving” as you plowed through a Nachos BellGrande, a Quesarito Combo, and a Crunchwrap Supreme.

Well, you were right—you were starving. Or at least, your body thought you were. And that's because of tetrahydrocannabinol, also known as THC, which is the main psychoactive component in marijuana.

A 2015 study conducted on mice by researchers at the Yale School of Medicine found that THC flipped a switch in the rodents' brain circuitry, making them feel hungry rather than full.

“By observing how the appetite center of the brain responds to marijuana, we were able to see what drives the hunger brought about by cannabis and how that same mechanism that normally turns off feeding becomes a driver of eating,” said Tamas Horvath, the study's lead author.

“It’s like pressing a car’s brakes and accelerating instead,” Horvath explained. “We were surprised to find that the neurons we thought were responsible for shutting down eating, were suddenly being activated and promoting hunger, even when you are full. It fools the brain’s central feeding system.”

Assuming that THC has a similar effect on humans, it's easy to understand how smoking weed would produce insatiable cravings for anything and everything.

But that’s not the only science at work when it comes to getting the munchies: THC also binds to cannabinoid receptors known as CB1s in the brain's olfactory bulb, making food aromas more intense, which increases your perception of flavor. So not only are you convinced that you’re ravenous, but things smell and taste better than they do when you’re not high, which is kind of a double whammy.

While this all may be a little annoying if you’re trying to cut back on your fast-food intake, the link between hunger and THC is potentially great news for people who have trouble eating due to illness or other medical reasons. For instance, marijuana has been shown to be an effective appetite stimulant in cancer patients. If researchers know exactly what causes that appetite surge, they may be able to use the munchies to benefit those who need it.

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Feeling Down? Lifting Weights Can Lift Your Mood, Too
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There’s plenty of research that suggests that exercise can be an effective treatment for depression. In some cases of depression, in fact—particularly less-severe ones—scientists have found that exercise can be as effective as antidepressants, which don’t work for everyone and can come with some annoying side effects. Previous studies have largely concentrated on aerobic exercise, like running, but new research shows that weight lifting can be a useful depression treatment, too.

The study in JAMA Psychiatry, led by sports scientists at the University of Limerick in Ireland, examined the results of 33 previous clinical trials that analyzed a total of 1877 participants. It found that resistance training—lifting weights, using resistance bands, doing push ups, and any other exercises targeted at strengthening muscles rather than increasing heart rate—significantly reduced symptoms of depression.

This held true regardless of how healthy people were overall, how much of the exercises they were assigned to do, or how much stronger they got as a result. While the effect wasn’t as strong in blinded trials—where the assessors don’t know who is in the control group and who isn’t, as is the case in higher-quality studies—it was still notable. According to first author Brett Gordon, these trials showed a medium effect, while others showed a large effect, but both were statistically significant.

The studies in the paper all looked at the effects of these training regimes on people with mild to moderate depression, and the results might not translate to people with severe depression. Unfortunately, many of the studies analyzed didn’t include information on whether or not the patients were taking antidepressants, so the researchers weren’t able to determine what role medications might play in this. However, Gordon tells Mental Floss in an email that “the available evidence supports that [resistance training] may be an effective alternative and/or adjuvant therapy for depressive symptoms that could be prescribed on its own and/or in conjunction with other depression treatments,” like therapy or medication.

There haven’t been a lot of studies yet comparing whether aerobic exercise or resistance training might be better at alleviating depressive symptoms, and future research might tackle that question. Even if one does turn out to be better than the other, though, it seems that just getting to the gym can make a big difference.

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Uncombable Hair Syndrome Is a Real—and Very Rare—Genetic Condition
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Everyone has bad hair days from time to time, but for roughly 100 people around the world, unmanageable hair is an actual medical condition.

Uncombable hair syndrome, also known as spun glass hair syndrome, is a rare condition caused by a genetic mutation that affects the formation and shape of hair shafts, BuzzFeed reports. People with the condition tend to have dry, unruly hair that can't be combed flat. It grows slower than normal and is typically silver, blond, or straw-colored. For some people, the symptoms disappear with age.

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Although there have been only about 100 documented cases worldwide, one of the world's leading researchers on the condition, Regina Betz, of Germany's University of Bonn, believes there could be thousands of others who have it but have not been diagnosed. Some have speculated that Einstein had the condition, but without a genetic test, it's impossible to know for sure.

An 18-month-old American girl named Taylor McGowan is one of the few people with this syndrome. Her parents sent blood samples to Betz to see if they were carriers of the gene mutation, and the results came back positive for variations of PADI3, one of three genes responsible for the syndrome. According to IFL Science, the condition is recessive, meaning that it "only presents when individuals receive mutant gene copies from both parents." Hence it's so uncommon.

Taylor's parents have embraced their daughter's unique 'do, creating a Facebook page called Baby Einstein 2.0 to share Taylor's story and educate others about the condition.

"It's what makes her look ever so special, just like Albert Einstein," Taylor's mom, Cara, says in a video uploaded to YouTube by SWNS TV. "We wanted to share her story with the world in hopes of spreading awareness."

[h/t BuzzFeed]

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