When you have poor posture, your muscles and tendons get used to that same position. More than likely, you probably also slouch while on the toilet as you scroll through your cell phone or read a newspaper. Your knees might be lower than your hips, which can close off your anus and abdominal muscles and make it harder to poop. (See if this DIY Squatty Potty can raise your knees).
Slouching throughout your day, especially after eating, makes it harder for your food to digest. Think about your stomach under your breast area as you’re hunched over. There isn’t much room because you’re putting pressure on your front body. This could cause some of the stomach acid to move up and cause acid reflux. Your intestines also don’t have room to move, and food could have trouble moving through your digestive system, making you feel bloated or constipated. Your bladder could also be compressed and cause urinary incontinence, especially if your pelvic floor muscles are weak.