It doesn’t matter how great your day is going. If you’re experiencing bloating and gas — common side effects of indigestion — it’s really hard to keep a smile on your face. And unfortunately, plenty of different foods could be to blame. “Our digestive system is home to trillions of microbes that help break down our food and keep our intestines healthy,” explains Layne Lieberman, MS, RD, nutritionist and author of Beyond the Mediterranean Diet: European Secrets Of the Super-Healthy. But we can easily screw it up by eating foods that mess with the good bacteria, she explains. Here are 14 foods to skip (or at least limit) to keep your belly — and your life — running as smoothly as possible.

ARTIFICIAL SWEETENERS

Consider this yet another reason to ditch diet soda for good. One study found that when people consumed artificial sweeteners — aspartame, sucralose, and saccharin (a.k.a. Equal, Splenda, and Sweet’N Low) — the gut bacteria that controls metabolism was altered. That can lead to all sorts of gastrointestinal (GI) problems, including an increased propensity to convert food into fat, says Lieberman. Meaning not only does it become more difficult to lose weight, but it’s actually easier to gain. Not cool.

COFFEE

Your daily pick-me-up could be doing more than just waking you up. “Not only is coffee acidic, but it also contains caffeine, which speeds up the digestive tract and may cause diarrhea,” explains Katie Cavuto, MS, RD, a nutritionist and chef in Philadelphia. That caffeine is also a diuretic, she explains, meaning it can lead to dehydration and even nausea. What’s more: Coffee causes the stomach to produce hydrochloric acid (HCL), which can cause heartburn and indigestion. So if you find yourself regularly experiencing GI issues after your cup of joe, limit it to one cup a day and don’t drink it on an empty stomach to help ease those unpleasant symptoms.