In this week’s Health newsletter, we discover how low-intensity workouts change your body, describe a bad side effect of weed ... and demystify why dogs can help you relax more than friends. Plus, what is that ‘triangle of death’
on your face?

PHOTOGRAPH BY BILL MARR, NAT GEO IMAGE COLLECTION  

ER visits have doubled in four years. Recurring episodes of nausea, vomiting, and severe abdominal pain. Why? They are classic signs of a puzzling gastrointestinal condition suffered by millions that’s associated with frequent, long-term use of marijuana.

Related: Do you smoke weed recreationally? Here’s what scientists want you to know. 
Also: Another strange condition that has doubled in recent years

PHOTOGRAPH BY MAX LOWE, NAT GEO IMAGE COLLECTION

You don’t have to push yourself to exhaustion. New studies show the power of light-intensity workouts. Added benefits: They create fewer injuries—and are easier to keep doing. 

Related: 
--No time for daily workouts? Weekend exercises can offer the same benefits.
--What lifting weights does to your body—and your mind

PHOTOGRAPH BY RYTIS BERNOTAS, GETTY IMAGES 

PHOTOGRAPH BY JOEL SARTORE, NAT GEO IMAGE COLLECTION 

It may seem like a mystery. Why does a dog lower your anxiety and improve your mood more than humans, even good friends? These experts explain. 

Related: Truth and myths about pets and your health 
Also: Dogs and their owners really do look alike. Here’s why.

Today’s Soundtrack: Got ‘til It’s Gone, Janet Jackson (feat. Q-Tip, Joni Mitchell)

Today’s newsletter was edited and curated by David Beard and produced by Alisher Egamov. Thanks for reading! Have a suggestion? Let us know.