heartburn happens when the contents of your stomach rise up into your esophagus, where stomach acids can burn the tissue. In some cases, you might be having an episode of heartburn because tight clothing is compressing your stomach. If that’s the case, the first thing to do is loosen your belt — or your pants, dress, or whatever else is holding you tight. Your posture can also contribute to heartburn. If you’re sitting or lying down, try standing up. If you’re already standing, try standing up more straightly. An upright posture puts less pressure on your lower esophageal sphincter (LES). Your LES is a ring of muscle that helps stop stomach acid from rising into your esophagus.