Cheese (and other dairy products)
You probably don't need a doctor to tell you that cheese -- known by some as dairy heaven, others as dairy crack -- can screw up your gut and haunt your roommates for days. If you're one of the 65% of adults who are lactose intolerant, the aftereffects can feel like coming down from a hard drug; it wreaks havoc on your GI tract. "Cheese (and dairy) contain lactose that when consumed by people with lactose intolerance can lead to bloating, gas pains/abdominal cramping, and diarrhea," Dr. Caguiat says. "This happens because the enzymes that break these sugars (lactose is a form of sugar) are lacking in susceptible people as they age. The gut bacteria end up digesting them (fermentation), leading to gas production (hence the bloating and crampy pain), and this draws water into the colon, leading to diarrhea."
Basically, cheese turns most people into farty, bloaty, runny messes. But it's totally worth it.
Yet another reason to keep eating your veggies; they help you have healthy poops. "A high-fiber diet is good for colon health as it helps bulk up the stools and draws water into the colon to help pass soft stools," Dr. Caguiat says. But there can be too much of a good thing.
"Too much fiber can have the opposite effect, constipation, especially when you eat much more than you consume water," she adds. "Also beware that certain vegetables are gas-producing (cruciferous vegetables like cabbage, broccoli, etc.) so this can lead to bloating and gas pains."
Aside from the lethal amount of sugar and calories and resulting spike in blood glucose levels, there's another reason to limit your intake of candy and treats. "Similar to fruits and alcohol, [sweets] tend to cause more bloating and diarrhea by the same way of fermentation," Dr. Caguiat explains.