Coconut oil can cause diarrhea when either you consume too much coconut oil or you eat it on an empty stomach. If you meet both conditions together, you're in for a severe diarrhea that can last for 12 hours or even longer.
Why does coconut oil have such a strong side effect?
It's all because of its medium-chain triglycerides (MCTs). They're relatively smaller in size. Hence, they can digest faster and break down quickly into glycerols and MCFAs (medium-chain fatty acids). This pair is the key to stimulating bowel movement and make you poop a lot. How?
Glycerols help to soften your hard, dry stools while MCFAs improves the motility of your intestinal muscles.
If you look at the way they function, they're actually helping the body to detox. In other words, the diarrhea caused by eating coconut oil is actually beneficial rather than detrimental. Unlike the one that's caused by food poisoning, which might lead to brain damage or even death.
That explains why so many people are turning to coconut oil for constipation.
Actually, as long as you don't take too much on an empty stomach coconut oil should not trigger the side effect.
As far as my experience goes, one teaspoon of coconut oil on an empty stomach should be safe. Even if it does give you the runs, the effect should be mild and short-lived. A safer way to avoid triggering diarrhea is to eat coconut oil with food.